The Journal for Equine Nutrition - Autumn '21 Page 10

Issue 2 The Journal for AuTuMN 2021 Equine Nutrition Forage options For horses Professor Jo-Anne Murray & Dr. Simon Daniels pre- & probiotics Dr. Helen Warren equine colic & its associated risk Factors Abigail Malone BSc a holistic approach to supporting your horse’s mobility Dr. Stephanie Wood the role oF physiotherapy in supporting mobility Jessica Seeley MSc Vet Phys nutrition oF the weanling Foal: weaning to 12 months Abigail Malone BSc PB 1The Journal for Equine Nutrition is FREE. To get every edition of The JEN to your inbox for free, sign up today at You will receive no marketing literature, and you will be the first to receive The JEN! Editor Contact us Dr Stephanie Wood 01986 782368 [email protected] [email protected] Feedmark Ltd, Church Farm, St Cross South Contributors Elmham, Harleston, Norfolk, IP20 0NY With special thanks to Dr. Helen Warren, Professor Jo-Anne Murray, Dr. Simon Daniels, Jessica Seeley, Stephanie Taylor, and Abigail Malone. Whilst every care has been taken in compiling this publication The JEN shall not be made liable for any inaccuracies therein. Production & Design The opinions expressed in this publication are not necessarily Penny Church those of the Editor/Publisher. [email protected] 2 3Welcome Welcome to the second issue of the JEN. We received microbial populations, and how they are a useful addition extremely positive feedback on the first issue from horse to the equine diet. Feedmark’s Senior Nutritionist, Abigail owners and equestrian professionals and aim to build on Malone, then outlines the risk factors for colic and the that success with this and all future publications. This issue steps you can take to reduce the likelihood of this issue covers the autumn season which often brings about changes developing, as colic is thought to be more prevalent at this in our horses’ management and nutrition due to evenings time of year. becoming darker and changes in the condition of our fields Maintaining mobility when the days are shorter and and amount of grass available. As such, the articles aim to turnout is reduced, is also a concern for many owners so I support you and your horse through those changes. have written an article on how you can support your horse’s One of the dietary changes that many horses experience mobility through appropriate management, exercise, in autumn is an increase in the amount of forage they and nutrition. Contributions from International Dressage consume. Reduced grass growth, often accompanied by Rider Steph Taylor and Certified Animal and Human REP wetter weather, lead to the feeding of more forage, either Physiotherapist Jessica Seeley, to that article are greatly AP in the field or when stabled. As forage should comprise the appreciated. The final, very timely article is by Abigail DEL majority of the equine diet, it is important to know which Malone, covering the very important topic of weanling CY forage is the most suitable, and what factors to consider nutrition. For anyone with a youngster or involved in CER when choosing your horse’s forage. A collaborative article breeding, this concise article provides key information on %0 by Professor Jo-Anne Murray (University of Glasgow) and the nutrient requirements of the growing foal. 01 N Dr. Simon Daniels (Royal Agricultural University) will I hope you enjoy reading the JEN and find the articles O help guide your forage selection by reviewing different D informative and supportive for managing your horse. ET forage types and their pros and cons. Supporting the horse’s NIR gastrointestinal health through dietary and management P changes is also important and can help efficient utilisation of the diet and reduce the likelihood of gastrointestinal issues developing. Dr. Helen Warren discusses how pre- Dr. Stephanie Wood and probiotics support the digestive environment and Editor CONTENTS 4 20 Forage options for horses A holistic approach to supporting your horse's mobility 10 35 Pre- and probiotics Nutrition of the weanling foal: from weaning to twelve months 15 Equine colic and its associated risk factors 39 Glossary 2 3Forage options for horses Professor Jo-Anne Murray, PhD, MSc, PgDip, PgCert, BSc (Hons), BHSII, RNutr, PFHEA, FRSB University of Glasgow & Dr. Simon Daniels, PhD, PgCert, BSc (Hons), SFHEA, R.Anim.Sci, Senior Lecturer at Royal Agricultural University Forages represent a diverse range of feedstuffs that CHEMICAL & STRUCTURAL CHARACTERISTICS form the basis of the diet of herbivorous domestic animals, OF FORAGES including horses. In the UK, forages are derived from In terms of their chemical composition, forages contain a number of sources; however, the principal forage is carbohydrates (CHO), protein, a small amount (~5%) of undoubtedly grass, which may be consumed in situ (i.e. lipid (oil), vitamins and minerals. The mineral content of grazing) or after conservation as silage or field-cured hay pasture plants is variable and depends on several factors (Beever & Mould, 2000). The most frequently used grass such as plant species, soil type, stage of growth, fertiliser species include the ryegrasses; perennial ryegrass (Lolium usage etc. In terms of vitamins, as a rule of thumb most perenne) and Italian ryegrass (Lolium multiflorum), Timothy green forage crops are an excellent source of the Vitamin (Phleum pratense), Cocksfoot (Dactylis glomerata), and A precursor β-carotene, Vitamin D precursor ergosterol, the fescues (Festuca spp.). Vitamin E and many of the B vitamins. Legumes are also important forage crops, which have The structural characteristic of forages is an important received increased attention in recent years as the need aspect of their nutritional value. The presence of a cell wall to reduce both the economic and environmental costs of surrounding the cell contents is one of the characteristic UK livestock production has risen. Forage legumes are features of plant cells that differs to animal cells. This wall valuable in agricultural systems due to their ability to ‘fix’ functions to provide rigidity and protection to the plant nitrogen from the atmosphere through their association without preventing diffusion of water and ions from the with nitrogen-fixing bacteria contained within root nodules. environment into the plant cell. As the plant matures, the The main forage legumes grown in temperate climates, ratio of cell wall to cell contents increases, especially in such as the UK, are species of Trifolium and Medicago, the stem, as a means of providing support for the growing more specifically, red clover (Trifolium pratense), white plant. Therefore, plant cells as a whole contain nutrients that clover (Trifolium repens) and Lucerne (Medicago sativa). are present in the contents of the cell (proteins, lipids, and As such, the small amount of Lucerne grown in the UK is non-structural carbohydrates) and also nutrients that reside harvested mainly for silage or artificial drying. However, in the cell wall, which predominantly consists of structural in other parts of the world, notably the USA and middle CHOs and some proteins. Structural CHOs are divided into east (where it is known as alfalfa), the crop is also used three classes, cellulose, hemicellulose and pectin. for grazing and sun-drying. The nutritional value of forages Plant cell wall components are generally referred to as is positively related to their degradability, which in turn is the fibrous fraction of the plant and are often collectively related to their chemical composition. Thus, to evaluate described by the term dietary fibre. Plant cell walls serve as the nutritional value of forages for horses it is important to a major source of energy for horses, as the structural CHOs examine their chemical and structural features. 4 5Professor Jo-Anne Murray, PhD, MSc, PgDip, PgCert, BSc (Hons), BHSII, RNutr, PFHEA, FRSB Professor Jo-Anne Murray has a PhD in Equine Nutrition, a MSc in e-learning, a PgDip in Animal Nutrition, a PgCert in University Teaching, and a degree in Equine Science. She is Principal Fellow of the Higher Education Academy, Registered Nutritionist with the Association for Nutrition and Fellow of the Royal Society of Biology. Jo-Anne has a record of outstanding achievement in leading education. Jo-Anne led the highly acclaimed MOOC in Equine Nutrition, with over 70,000 participants from across the globe. Jo-Anne also led the first online distance learning programme in Animal Nutrition. Jo-Anne has a dual portfolio of research in animal nutrition and education. Her nutrition work is focused on: (i) improving diet digestibility; (ii) the role of diet on the gut microbiome; (iii) the gut-brain axis; and (iv) the role of supplements/feed processing on gut health, the microbiome and behaviour. Jo-Anne has established collaborations with industrial and academic partners in the UK and internationally. Jo-Anne’s R education research has evaluated MOOCs, mobile apps and virtual worlds. She has also evaluated horse owners’ EPA feeding practices/knowledge of nutrition and veterinarians’ perceptions/knowledge of nutrition. She has published over P D 130 peer reviewed articles, numerous lay articles/blogs, is a journal editor (Animal) and reviewer, and invited speaker. ELCYC are degraded in the hindgut of the horse by the resident legumes, such as alfalfa, and accumulates in the leaves ER microbes, which produce volatile fatty acids (VFAs) that and seeds of these crops (McDonald et al., 2011). Starch %001 are used as an energy source by the horse. is a polymer (chain) of glucose residues and in legumes, N starch is only accumulated in small amounts up to 50g/kg O It is important to understand CHOs in horse diets, DE DM (5%) (Campbell, 1996). In human diets, when we talk T because how we refer to these in horse diets is different to NI about CHO, we are usually referring to starch. In horses, R how we think of them in our own diet. In humans, we often P we cannot feed a low CHO diet because horses need fibre talk about a low CHO (or low carb) diet. This refers to a in their diet and fibre contains high amounts of structural low non-structural CHO (NSC) diet. The NSCs in forage CHOs (see Your horse’s gut: gastrointestinal structure and crops include simple sugars, fructan and starch. The storage function in JEN issue 1). carbohydrates of temperate grasses include fructan and the sugars glucose, fructose and sucrose, which together Another constituent of the plant cell wall is lignin. constitute the ‘water soluble carbohydrate’ (WSC) fraction Lignin is a compound you may have heard of. It is of the plant. In temperate grasses, fructan is the most important to point out that lignin is not a CHO, but it is abundant NSC, and is mainly found in the stem of the plant closely associated with them. As the plant grows, the (Pollock & Cairns, 1991). The fructan content of grasses amount of structural CHOs present increases along with may vary depending on light intensity, photosynthetic lignin. Lignin provides structural strength to the plant and rates, temperature and growth rates, and under favourable is therefore present in higher amounts in the plant stem. conditions they may constitute a considerable proportion Lignin is almost completely indigestible and because it of total dry matter (DM) of the grass (Longland & Byrd, entwines itself around the structural CHOs it can reduce 2006). By contrast, starch is the storage carbohydrate of the digestibility of them by preventing the microbes in the 4 5Hay is plant material that has been air-dried to a hindgut from accessing the cellulose, hemicellulose and sufficiently low moisture content (~15% or less), to ensure pectin. This is why more mature forages, such as grass a stable product resistant to microbial degradation under hay, which has a greater proportion of stem compared to ambient conditions (van Soest, 1994). The process of hay younger pasture, is less digestible than immature grass in making involves cutting the grass, turning the grass in the pastures. Therefore, in terms of digestibility, the extent to field over a number of days to aid drying before baling. which fibre is degraded in the hindgut varies according to This takes around 5 days and is highly weather dependent plant species, stage of growth and the composition of the which, in the UK, is generally most favourable in early cell wall (Nordkvist, 1987). Therefore, it is advisable to summer when the herbage is relatively mature, and thus analyse forage to understand its nutritional composition, has a higher DM content than immature crops (Figure 1). which varies considerably as seen in Table 1. In artificial dehydration, younger, high-digestibility Table 1. Composition of grass hay (g/kg DM, unless otherwise stated) herbage of high moisture content can be dried when field Nutrient Typical ranges drying would be impossible, and thus a short-cutting Digestible energy (DE) Mj/kg DM 7.5 - 9 cycle regime (i.e. a cutting interval of less than 36 days) Crude protein (CP) 70 - 150 is generally employed for herbage that is conserved in Acid detergent fibre (ADF) 340 - 440 this manner (Givens et al., 1992). Drying can occur at Neutral detergent fibre (NDF) 550 - 700 either relatively low temperatures (150-250℃), or more Water soluble carbohydrate (WSC) 70 - 160 Ethanol soluble carbohydrate (ESC) 45 - 100 commonly at high temperature (600–1000℃) in rotary- Starch 0.5 - 3.5 drum driers. In the process of high-temperature (HT) Ash 57 - 100 drying the herbage is mown, wilted overnight, harvested to Crude fat 18 - 33 a chop length of 75mm lengths (necessary for the operation Mj: megajoules of the drying equipment), dried, cooled, and stored for future use. Artificial dehydration is the most efficient CONSERVED FORAGES FOR HORSES Pasture herbage is the natural feed of horses; however, seasonal growth in temperate climates necessitates the need to conserve forage for winter feeding. Furthermore, many performance horses receive little time at pasture, regardless of season; subsequently many receive their forage in a conserved form all year round. The main objective of forage conservation is to preserve as much of the digestible nutrient content of the herbage as possible. This can be achieved in several Figure 1. Schematic of the characteristics of hay, haylage and silage made without additives, showing the requirements for making quality ways; a) by reducing the moisture content to a level at forage. (WSC – water soluble carbohydrate content, pH – acidity level of forage, lactate – starts to be produced when WSC and pH decline). which chemical breakdown and microbial degradation (adapted from Harris et al., 2017). cease, as in haymaking and artificial dehydration; or b) by method of conserving forage, since nutrient losses are low, the acidification of high moisture herbage by anaerobic resulting in material that has a similar feeding value to fermentation, which inhibits the activities of plant enzymes the original herbage. and spoilage microorganisms, as in silage making. 6 7Quite distinct from the conservation of herbage by be variable. Haylage is more commonly fed to horses and drying, is the process of ensiling, in which high moisture can be made from a variety of crops, including grasses herbage is preserved by the anaerobic fermentation of and legumes, but is commonly made from grass in the plant WSC to lactic acid, by lactic acid bacteria present UK. The process of haylage making involves cutting on the forage. The production of lactic acid lowers the the grass, turning the grass once to reduce some of the pH, inhibiting plant enzyme activity and the growth of moisture content (also known as wilting) and then baling undesirable spoilage microorganisms, such as clostridia and and wrapping the haylage. This process takes two to three enterobacteria spp., thus ensuring effective and hygienic days, whereas in silage making the grass is typically cut, preservation of the herbage. The exact level of acidity baled and then wrapped the following day as silage has a required to inhibit clostridial activity is dependent on the higher water content than haylage. DM content of the silage (Woolford, 1984). Clostridia can In the UK, hay, haylage and silage are most commonly tolerate high concentrations of acid in environments where made from grass; however, it is also possible to preserve water is freely available, whereas, on wilted material with alfalfa in these different ways (Murray et al., 2007). The a DM content of above 350g/kg clostridia are inhibited by main issues are the climate in the UK to field dry the alfalfa a lack of moisture and therefore such a decrease in pH is R for hay, this is commonplace in other parts of the world, EP not required. This explains the difference between silage A and also the alfalfa itself is less suitable for ensiling due P and haylage, silage has a higher moisture content than D to its low WSC contents. It is very common in the UK to EL haylage and is why haylage can be difficult to classify as it C preserve alfalfa by high temperature drying. YC sits somewhere between hay and silage. It is wetter when ER FEEDING CONSERVED FORAGE conserved than hay and relies on air exclusion but has a %00 Horses are commonly fed a variety of forages, both long lower moisture content than silage (Harris et al., 2017). 1 N forage in the form of hay or haylage, and short chopped Because the moisture content of haylage could be between O D forages such as high temperature dried alfalfa. 15-40% the conservation, e.g. amount of fermentation, can ETNIRP Dr Simon Daniels, PhD, PgCert, BSc (Hons), SFHEA, R.Anim.Sci Simon is a Senior lecturer at the Royal Agricultural University in Equine Science. Simon studied Equine and Animal Science at the University of Lincoln, after graduating he worked for a horse feed manufacturer as part of the nutrition team before moving on to work for the University of Liverpool on a parasitology project within the School of Veterinary Medicine. Simon went on to complete a PhD in equine anthelmintics, efficacy and effects on intestinal health with Prof Chris Proudman at the University of Surrey School of Veterinary Medicine and Science. Simon has been lecturing in higher education since 2012, and joined the RAU in 2014. Simon’s research interests remain within equine gastrointestinal health and disease including both parasitology and nutrition and their effect on normal gut function. Gut health is directly influenced by diet and nutrition and therefore Simon is also interested in the management of grasslands and how both fresh and conserved forage can influence gut heath. 6 7Feeding horses conserved forage is typically associated differing dry matters in the same way that they eat haylage, with feeding hay, however a range of conserved forages which is essentially just dryer silage. can be fed to horses (Figure 2). Historically hay has been Making use of ensiled forages such as haylage and silage identified as the most popular UK forage for horses (King, has been used successfully to replace the need for cereal 2012) however changing weather patterns, difficulties concentrates in both young growing foals (Moore-Colyer et in sourcing small bales, and convenience have led to an al., 2020) and in performance horses in training (Ringmark increased use of haylage (Waring et al., 2021). Waring et al., 2013) without affecting performance. Ensiled forages et al. (2021) identified that horse owners do have an therefore provide a high energy and high fibre diet option understanding of what haylage is, but in their study, there with health benefits to horses, e.g. increased chewing time was some confusion over spoilage times once a bale was and reduced risk of growth abnormalities, without limiting open, the suitability of haylage for differing horses, and performance or growth trajectory. Moreover, feeding types of analysis that can be carried out on haylage to forage helps maintain gastric health (Harris et al., 2017), gauge nutrient and hygiene quality. Historically there was and additionally feeding alfalfa can also help maintain pH a belief that horses would not eat silage as it was “too in the upper part of the stomach as alfalfa can buffer any rich” and “unpalatable”, however previous feed intake decline in pH (Stowers et al., 2013). There is a perception by some equine dental technicians and veterinarians that ensiled forages are associated with peripheral dental caries (cavities due to tooth decay), and this has been partly supported by Gere & Dixon (2010) who investigated incidences of caries in cheek teeth of horses from a Swedish abattoir where silage was commonly fed. Another area of potential haylage confusion as identified by Waring et al. (2021), is that if Figure 2. Haylage is the most common wrapped forage fed to horses haylage/silage is well fermented then it should be low in although research has shown that silage can also be a suitable feedstuff. water soluble carbohydrates (WSC) as WSC is used in the studies of Moore-Colyer & Longland (2000) and Muller & process of fermentation. Waring et al. (2021) found most Uden (2007) both identified in preference trials that intake horse owners thought haylage would have higher WSC, was greatest for silage, then haylage, and hay was the which if the haylage has a higher DM and is conserved least preferred and always the forage with some orts left. by air exclusion with little fermentation, then potentially Interestingly Moore-Colyer & Longland (2000) identified the WSC could be higher than hay. The WSC content of that horses would eat clamp silage, however their intake haylage will depend on the grass sward the forage was was significantly less than baled silage or haylage, but the produced from and the maturity of the plant at the time of quantity ingested met their nutrient requirements, therefore cutting. Notably, Waring et al. (2021) identified owners suggesting that the nutrient profile triggered the voluntary were concerned about feeding horses with gastric ulcers or food intake response, preventing excess intake. Clamp laminitis haylage. When compared to concentrates haylage silage is likely to have a higher moisture content than baled does not appear to cause a significant drop in stomach pH silage and therefore a different nutrient profile. Collectively (Moore-Colyer et al., 2020) and as with long forage, the these studies suggest that horses will happily eat silage at chewing involved produces ample saliva to buffer gastric 8 9juice. While theoretically ensiled forages could be lower in that the different conservation processes between hay and WSC and therefore appear more suited to laminitic prone haylage alter the gut microbiota to degrade the differing animals, the overall energy content of this forage could still forages and produce different metabolic profiles within the be too great. Depending on the conservation, species and animals reflecting this. This therefore suggests that while DM, haylage could be higher in WSC than hay and illicit both hays and ensiled forages all start as grass, the way a higher glycaemic response, as demonstrated by Carslake they are preserved influences the way they are metabolised. et al. (2018) where haylage increased blood glucose SUMMARY more than hay, and soaked hay had the lowest response. Collectively these different studies suggest that ensiled When considering this we should be mindful that this will forage of differing dry matters can be highly beneficial be influenced by the grass sward, plant maturity and the to horses, including young rapidly growing animals DM content at conservation and this may be of concern and performance horses, to reduce the need for cereal for animals with metabolic conditions but not for concentrates which can provide health benefits to horses. healthy animals. There are some situations where ensiled forages may More recently Leng et al. (2021) identified that ponies not be suitable for specific types of horses and ponies, R fed haylage as opposed to hay had altered gut microbiota notably these appear to be in animals prone to laminitis. EPA and metabolic profiles than hay fed horses. The findings By knowing the profile of your forage e.g. the type of grass P D of this study altered with season, and this is supported by it was conserved from, the plant maturity at cut and the ELC Salem et al. (2018) who noted the faecal microbiome of moisture content and nutrient profile, then it should be YCE grass kept horses altered when they were supplemented possible to decide if you have the most suitable forage for R % with haylage. The findings of Leng et al. (2021) suggest the requirements of your horse. 001 NO REFERENCES D Beever, D. E., & Mould, F.L. (2000). Forage evaluation for efficient ruminant livestock production. In: Givens, D.I., Owen, E., Axford, R.F.E., Omed, H.M. (eds) Forage Evaluation in Ruminant E Nutrition. CAB International: 15-42, Oxen, UK. TN Campbell, N. A. (1996). Biology. The Benjamin/Cummings publishing company, Inc., California, USA. IR Carslake, H.B., McG. Arge, C., Pinchbeck, G.L., Dugdale, A.H.A., & McGowan, C.M. (2018). Insulinaemic and glycaemic responses to three forages in ponies. The Veterinary Journal, 235: 83-89. P Gere, I., & Dixon, P.M. (2010). Post mortem survey of peripheral dental caries in 510 Swedish horses. Equine Veterinary Journal, 42(4): 310-315. Givens, D. I., Moss, A.R., & Adamson, A.H. (1992). The Chemical Composition and Energy Value of High-Temperature Dried Grass Produced in England. Animal Feed Science and Technology, 36(3-4): 215-228. Harris, P.A., Ellis, A.D., Fradinho, M.J., Jansson, A., Julliand, V., Luthersson, N., Santos, A.S., & Vervuert, I. (2017). Review: Feeding conserved forage to horses: Recent advances and recommendations. Animal, 11(6): 958-967. King, L. (2012). A survey of forage feeding practices in UK. BSc thesis. Royal Agricultural College, Cirencester, UK. Leng, J., McNally, S., Walton, G., Swann, J., Proudman, C., Argo, C., Emery, S., La Ragione, R., & Eustance, R. (2021). Hay vs Haylage: Forage type influences the equine urinary metabonome and faecal microbiota. Equine Veterinary Journal. doi: 10.1111/evj.13456 Longland, A.C., & Byrd, B.M. (2006). Pasture nonstructural carbohydrates and equine laminitis. The Journal of Nutrition, 136(7): 2099S-2102S. McDonald, P., Edwards, R.A., Greenhalgh, J.D.F., Morgan, C.A., Sinclair, L.A., & Wilkinson, R.G. (2011). Animal Nutrition, 7th Ed. Pearson Education Ltd. Moore-Colyer, M.J.S., & Longland, A.C. (2000). Intakes and in vivo apparent digestibilites of four types of conserved grass forage by ponies. Animal Science, 71; 527-534. Moore-Colyer, M.J.S., Tuthill, P., Bannister, I., & Daniels, S.P. (2020). Growth rates of Thoroughbred Foals and in vitro gut health parameters when fed a cereal or an all-fibre creep feed. Journal of Equine Veterinary Science, 93: 103191. Muller, C.E., & Uden, P. (2007). Preference of horses for grass conserved as hay, haylage or silage. Animal Feed Science and Technology, 132(1-2): 66-78. Murray, J.M.D., Longland, A.C. Davies, D.R., Hastie, P.M., Moore-Colyer, M.J.S., & Dunnett, C. (2007). The effect of enzyme treatment on the nutritive value of lucerne for equids. Livestock Science, 112: 52-62. Nordkvist, E. (1987). Composition and Degradation of Cell Walls in Red Clover, Lucerne and Cereal straw. The Swedish University of Agricultural Sciences, Uppsala, Sweden. Pollock, C. J., & Cairns, A.J. (1991). Fructan Metabolism in Grasses and Cereals. Annual Review of Plant Physiology and Plant Molecular Biology, 42: 77-101. Ringmark, S., Roepstorff, L., Essen-Gustavsson, B., Revold, T., Lindholm, A., Hedenstrom, U., Rundgren, M., Ogren, G., & Jansson, A. (2013). Growth, Training response and health in standardbred yearlings fed a forage only diet. Animal, 7(5): 746-753. Salem, S.E., Maddox, T.W., Berg, A., Antczak, P., Ketley, J.M., Williams, N.J., & Archer, D.C. (2018). Variation in faecal microbiota in groups of horses managed at pasture over a 12-month period. Scientific Reports, 8: 8510 (2018). Stowers, N.L., Waldron, L.A., Pryor, I.D. Hill, S.R., & O’Brien, J. (2013). The influence of two lucerne-based forage feeds, FibreProtect® and FibreEdge® on Equine Gastric Syndrome in horses. Journal of Applied Animal Nutrition, 2: 1-6. van Soest, P. J. (1994). Nutritional Ecology of the Ruminant. Cornell University Press, New York, USA. Waring, B., Rousson, L., Daniels, S.P., Harris, P., & Moore-Colyer, M.J.S. (2021). What is haylage - UK horse owners’ perception. Journal of Equine Veterinary Science, 100: 103519. Woolford, M. K. (1984). The Silage Fermentation. Marcel Dekker Inc., New York, USA. 8 9Pre- and probiotics Dr. Helen Warren, PhD, BSc (Hons), PGCHE, R.Anim.Sci, MRSB, BHSISM bacteria for receptors in the gut. Bacteria able to better There are numerous nutritional supplements that target compete for receptor sites may prevent the adherence and intestinal health with the aim of stabilising the gut flora and subsequent colonisation of pathogenic bacteria. There has reducing the susceptibility of the host to disease (Yang et been speculation that production of antibacterial products al., 2009), including prebiotics, probiotics, enzymes and by DFM strains aids this competitive exclusion (Plaza- plant extracts (Murphy, 2017). Diaz et al., 2019). PROBIOTICS Aside from the intestinal effects, there is substantial The gut is home to a vast number of microorganisms, evidence that there are immune function effects, mainly mainly bacteria. These commensal bacteria are involved in concerning modulation of inflammation (Borchers et the two main functions of the gut: nutrient absorption and al., 2009). The native gut microbiota modulates the pathogen exclusion (competitive exclusion). The gut also has immune system via the production of molecules with a role in immune modulation and generation of metabolites immunomodulatory and anti-inflammatory functions that (Sanchez et al., 2017). Metchnikoff (1908) first developed are capable of stimulating immune cells (Plaza-Diaz et al., the concept of what we now know as probiotics. Probiotics, 2019). Certain strains of Lactobacillus used as DFMs are known as direct-fed microbials (DFM), are defined as able to stimulate or influence production of inflammatory live microorganisms that, when offered in sufficient molecules, such as interleukins (Borchers et al., 2009). amounts, can confer health benefits (Borchers et al., 2009; Increased levels of immunoglobulin (Ig) A have been Bermudez-Brito et al., 2012). Direct-fed microbials are reported in vitro and DFMs are also known to enhance strain-specific and effects of one can’t be extrapolated immunity beyond the gastrointestinal (GI) tract through to another. Most DFM are strains of commensal bacteria interactions with the common mucosal immune system or strains of the yeast, Saccharomyces cerevisiae. As far (Wang et al., 2016). In horses, variable results have been as bacteria go, the main bacteria used are Lactobacillus, noted. Many of the strains used in studies assessing the Bifidobacterium and Enterococci despite these not being efficacy of DFM in horses have used bacterial strains native the most abundant species in the digestive tract (Schoster to the human, rather than the equine, gastrointestinal tract. et al., 2014). Often the criteria for the selection of bacterial Swyers et al. (2008) noted limited effects on digestibility DFM include the tolerance to gastrointestinal conditions, or acidosis risk when mature Thoroughbred geldings were ability to adhere to the gastrointestinal mucosa, production supplemented with either a single or multiple, mixed species of antimicrobial factors and competitive exclusion of of bacteria added to a low- or high-starch concentrate. pathogens (Collins et al., 1998; Borchers et al., 2009; Increased Copper (Cu) and Iron (Fe) digestibility was seen Schoster et al., 2014). There are various modes of action with both DFM treatments. A recent meta-analysis (Cooke via which these DFM exert their effects, the key ones being et al., 2021) suggested no clear benefits from supplementing antimicrobial, immune modulation, competitive exclusion horses with probiotic bacteria on carbohydrate digestion or and inhibition of bacterial toxins (Plaza-Diaz et al., 2019). prevention of Salmonellosis. However, supplementation Competitive exclusion refers to the competition between 10 11appeared to increase stamina in exercising horses. They also soluble carbohydrates (starch and sugar) can lead to over- suggest that single-species DFM may not be as effective as production of VFA, particularly propionate and lactate and, multispecies supplementation. However, Ward et al. (2004), ultimately, a drop in pH and acidosis. Cellulolytic bacteria hypothesised that addition of Lactobacillus strains with are active within a narrow pH range (above 6.0, Russell & Enterococcus faecium has the potential to reduce faecal Wilson, 1996) and can only survive for a relatively short shedding of Salmonella in hospitalised horses. Additionally, time below this range before their growth and activity is feeding a commercial probiotic product containing compromised and fibre digestion is inhibited. Interest in Lactobacillus strains, together with Bifidobacterium boum yeast as part of animal diets has been cited as far back as reduced incidence and duration of diarrhoea in neonatal 1925 (Eckles & Williams, 1925, quoted in Newbold et al., Thoroughbreds from birth to 20 weeks of age (Tanabe et 1995) but its mode of action was not fully understood. Over al., 2014). Despite some encouraging results with bacterial the last three decades, in-depth investigation has revealed strains, currently, there are no bacterial strains registered that the main effects of yeast relate to alteration in microbial for use in horses in Europe. fermentation (Newbold et al., 1995). Primarily, yeast, or rather S. cerevisiae, stimulates the activity of cellulolytic R bacteria (Harrison et al., 1988; Newbold et al., 1995), EPA those that utilise lactate (Martin & Nisbet, 1992; Rossi et P D al., 1995), as well as total anaerobic bacteria (Newbold et ELC al., 1995; Lascano et al., 2009) in the rumen of foregut YCE fermenters, helping to reduce the amount of time the rumen R % pH falls below 5.5. The microbial ecosystem in the hindgut 001 of the horse is similar to that of the rumen, where both NO cellulolytic and amylolytic bacteria degrade carbohydrates, D Figure 1. S. cerevisiae is a useful probiotic that stimulates cellulolytic ET bacteria and efficient utilisation of the fibrous portion of the horse’s diet. thus addition of yeast to horse rations should yield similar NIR benefits, providing the yeast survives the acidic and slightly P The other main DFM is yeast. Yeasts reproduce by alkaline environments of the gastric stomach and intestine, budding or fission resulting in growth by groups of single respectively. The majority of beneficial bacteria in the cells (Kurtzman et al., 2011). The most well-researched, hindgut rely on a stable, anaerobic environment in order Saccharomyces cerevisiae, has many diverse functions in to function. S cerevisiae is known to scavenge (respire) both human and animal diets (Figure 1). Many different oxygen entering the rumen on feed particles (Newbold et strains of this yeast exist and all vary slightly with regards al., 1995), helping to promote an anaerobic environment to their effects in the animal (Newbold et al., 1995). and promoting anaerobic bacterial growth. Additionally, Horses have evolved to make use of low-quality, fibrous stimulatory co-factors are thought to be involved in feed material via microbial fermentation in the hindgut. increasing bacterial growth (Dawson et al., 1990; Jouany, This microbial ecosystem generates sources of energy 2006) meaning that live yeast is likely to be more effective via the breakdown of dietary ingredients. Volatile fatty compared with ‘dead’ or inactivated yeast. acids (VFA) are the end-product of bacterial fermentation Numerous beneficial effects have been reported for the of carbohydrates and are absorbed across the wall of the inclusion of yeast in equine diets. However, response of hindgut as an energy source for the horse. Diets high in 10 11animals to yeast inclusion is influenced by several factors, no such effects were seen in exercising or non-exercising including diet (Robinson & Erasmus, 2009) and yeast Arabs following dietary administration of live yeast strain (Newbold et al., 1995). However, not all yeasts (Gobesso et al., 2018). are the same and commercially available products are PREBIOTICS not comparable ‘gram for gram’. Commercially, there A prebiotic is a substrate that is selectively used by host are numerous yeast products available for use in equine microorganisms conferring a health benefit (Gibson et diets and other species. All are based on different strains. al., 2017). They are usually non-digestible carbohydrates Probably the major distinction between them is whether the that can be degraded by gut microbes (Davani-Davari et yeast is alive or dead. Live yeasts and bacterial strains for al., 2019) providing a feed source for commensal bacterial use in animal feed need to be authorised and registered by growth and/or activity. Fermentation of prebiotics by gut the E.C. Currently, there are four live yeasts registered for microbiota produces short-chain fatty acids (SCFAs), use in horses on the Feed Additives Register. including lactic acid, butyric acid, and propionic acid In horses, live yeast has been shown to stimulate (Davani-Davari et al., 2019). Production of these SCFAs the population of cellulolytic bacteria and their activity lead to a modulation of the immune function in the (Medina et al., 2002), as well as increase nutrient gut and beyond. The most common prebiotics include digestibilities (Glade, 1991a,b) (Figure 2). Additionally, fructooligosaccharides (FOS), galactooligosaccharides (GOS), inulin and mannan oligosaccharides (MOS). Additionally, these nondigestible ingredients often adhere to pathogens and can modulate immune parameters in the gut (Patel & Goyal, 2012). However, literature investigating the effects of prebiotics in horses is scarce and variable. Fructooligosaccharides are probably the most studied prebiotic in humans and some animals. They are composed of linear chains of fructose molecules that are not able to be hydrolysed by mammalian gut enzymes. Instead, they are fermented by microbes, particularly, in the hindgut to Figure 2. Utilisation of forage can be optimised by providing pre and produce SCFA. Dietary supplementation of FOS has led to probiotics in the horse’s diet. improved insulin sensitivity in obese horses (Respondek et al., 2011). Heaton et al. (2019) also noted that feeding FOS dietary supplementation with live yeast to ponies resulted may mitigate some reduction in digestibility in older horses. in increased acid detergent fibre (ADF – represents lignin Linked to digestion, Berg et al. (2005) noted lower levels and cellulose content in the plant cell wall) digestibility of faecal E. coli and increased faecal VFA concentrations and increased intakes of neutral detergent fibre (NDF following dietary supplementation with FOS. – represents the plant cell wall and indicates the fibrous fraction of the plant) and dry matter (DM) with both high Mannanoligosaccharides, in particular, have starch and high fibre diets (Jouany et al., 2008). These demonstrated consistent and reproducible benefits to results were similar to those of Salem et al. (2016) who the gut microbiota (Corrigan et al., 2015; Corrigan et al., 2018). Most MOS products are derived from the supplemented live yeast to Quarter Horses. Conversely, 12 13Dr. Helen Warren, PhD, BSc (Hons), PGCHE, R.Anim.Sci, MRSB, BHSISM In 1999, Dr. Warren achieved her primary degree in Animal Science from the University of Wales, Aberystwyth, followed by her PhD in fatty acids in beef from the Faculty of Medical and Veterinary Sciences at the University of Bristol. She spent five years lecturing degree students in animal and equine science before moving to industry. She is a Senior Visiting Fellow at Nottingham Trent University, a trustee of the British Society of Animal Science and Chair of their Membership and Accreditation Committee. She is also a qualified R lecturer, a Cow Signals Master Trainer and a registered EPAP Animal Scientist. She has recently joined the Food Standards Agency’s Animal Feed and Feed Additives Joint Expert DE Group. She currently works as a European Technical Manager for Ruminants and Horses for Alltech, involving initiating LCY European research projects, as well as delivering nutritional education and technical sales support. CER %0 reducing the risk of colonisation by the pathogen. There is cell wall of the yeast Saccharomyces cerevisiae. During 01 paucity in the literature regarding effects of MOS in horses, gut health challenges, there can be a predominance NO but Spearman and Ott (2004) found improved colostrum of a particular bacterial group, usually Firmicutes. DET quality in mares given MOS. Mannanoligosaccharides are able to influence microbial NIRP diversity by increasing the prevalence of another group of Inulin, which is usually derived from chicory and bacteria, the Bacteriodetes, while concomitantly reducing belongs to the same class of carbohydrates as fructans, and the abundance of Firmicutes, thus redressing the balance. GOS have similar modes of action to FOS and MOS but Again, increased production of butyric acid is associated inulin can be fermented by fewer gut bacteria compared with addition of this prebiotic and butyric acid has long been with the others. In some cases, both prebiotics and DFM are associated with beneficial effects on the gut epithelium. fed together. Horses receiving both Enterococcus faecium Additionally, reductions in undesirable proteobacteria and FOS exhibited altered blood parameters compared with have been noted with dietary inclusion of mannan-rich unsupplemented animals and those supplemented with fragments (MRF) (Corrigan et al., 2018). Bacteria bind either the DFM or prebiotic (Saeidi et al., 2021). to epithelial cells via lectins that recognise specific sugars on the cell surface. Many pathogenic bacteria found in SUMMARY the gut have Type 1 fimbriae (projections) that recognise While there is a reasonable amount of literature and bind to mannose. Mannan-rich fragments are able to on dietary addition of DFM, effects are variable, bind to these mannose-recognising projections and prevent probably due to small numbers, an issue common in the bacterium binding to the cell surface, subsequently, equine research. That said, most effects seen focus 12 13on beneficial modification of the gut microbiota, as studied in the horse to an even lesser degree. Promising well as stimulation of immune function. Prebiotics, effects have been seen with groups of oligosaccharides, defined as a substrate that is preferentially used by namely FOS and MOS. Further equine research is required host microorganisms to elicit beneficial effects, have been in this area. REFERENCES Berg, E.L., Fu, C.J., Porter, J.H., & Kerley, M.S. (2005). Fructooligosaccharide supplementation in the yearling horse: Effects on fecal pH, microbial content, and volatile fatty acid concentrations. Journal of Animal Science, 83: 1549–1553. 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World’s Poultry Science Journal, 65(1): 97-114. 14 15Equine colic and its associated risk factors Abigail Malone, BSc WHAT IS COLIC AND WHAT ARE THE SIGNS? symptoms of colic range from mild to severe (Table 1), with the worst cases resulting in death of the horse. Colic that Colic is the term used to describe a form of abdominal pain initially looks mild can quickly escalate to a severe case, associated with a problem that occurs in the gastrointestinal making it essential to always treat colic as a potentially tract (GT) of the horse (Frape, 2010). Unfortunately, colic serious condition and seek veterinary advice. is a common veterinary problem, accounting for one in Scantlebury et al. (2014) highlighted how horse owners three emergency vet call outs (Bowden et al., 2017). Horses that understand when veterinary interventions are needed who have previously had colic that has been treated either and who are aware of colic symptoms can help improve the medically and/or surgically, are at risk of having recurring outcome of a colic bout. They also emphasised that owners colic episodes (Gonçalves et al., 2002), evidenced by who understand how to manage horses appropriately will the finding that 11-16% of horses affected by colic have help to reduce the risk of colic issues. In a study by Bowden reoccurring colic episodes within a year (Scantlebury et R et al. (2020), involving 1564 horse owners, 55% of EP al., 2011). Broodmares (Kaneene, 1997), Arabs (Cohen, A participants either did not know or gave incorrect values for P 1999) and geldings (compared to stallions and mares) D their horse’s normal heart rate and respiratory rate, although EL (Abutarbush et al., 2005) are thought to be at greater risk C 67% of owners were able to give the correct value for their Y of colic although factors such as how the horse is managed C horse’s normal rectal temperature. When asked what they ER and the diet it is fed are known to greatly influence the would assess if they suspected their horse may have colic, %0 incidence of colic, meaning any horse of any age, breed or 0 76% said faecal output, 75% said gastrointestinal sounds, 1 sex can be affected. N 65% stated respiratory rate and 54% said heart rate. Overall, O D As colic does not discriminate, all horse, pony and many owners were undecided on when they would deem ET donkey owners should be able to recognise colic symptoms it necessary to call their vet, although 61% felt confident NIR and be aware of factors that increase the risk of colic. The that they could recognise most types of colic. This study P Table 1. Symptoms of colic in horses, ranging from mild to severe episodes. Universal signs Mild colic signs Moderate colic signs Severe colic signs Raised heart rate and Curling of the upper lip Violently rolling Positioning to urinate breathing rate more frequently Restlessness Unexplained excessive Lack of appetite Remaining on their side sweating when lying down Pawing the ground Reduced, lack of Breathing rapidly droppings or changes in Lying down and getting Watching their flanks consistency up more frequently Possibly injuries from rolling Depression/lethargy Kicking at stomach Holding head in unusual position, normally lowered Reduced or absent gut sounds 14 15also found that 54% of participants had experienced a horse bends back on itself (Greet & Rossdale, 1996; Towcester dying from colic, showing that more horse owners need to Equine Vets, 2021). be provided with the correct means to evaluate their horse’s SAND COLIC normal clinical parameters and be able to recognise the Sand colic is less common but can also cause a form of early signs of colic to give their horse the best chance of impaction. The impaction is due to the build-up of sand that survival and recovery. has been ingested and then remains in the large colon of the LI (Frape, 2010). Sand cannot be expelled via the faeces as TYPES OF COLIC AND THEIR RISK FACTORS the heavy particles sink to the bottom of the colon, meaning There are a number of different types of colic which that they do not pass along the GT with other normal ingesta can have either one or multiple causes and treatments. The particles which are expelled as faeces. Without treatment cause of colic can be due to either nutritional factors, non- or removal of the sand, the particles begin to build up and nutritional factors, or a combination of both, and for some cause irritation (Frape, 2010), with recurrent colic likely cases of colic it may be difficult to pinpoint the if the issue is not treated. Although sand colic may be original cause. less well known, for horse owners in sandy regions it is a real concern as their horses are more likely to ingest sand SPASMODIC COLIC particles than horses living in non-sandy regions. Sand Spasmodic colic is the most commonly seen form of colic can be caused by horses in sandy regions grazing colic in horses (Greet & Rossdale, 1994), with one study close to the ground due to low grass availability, or due by Proudman (1992) reporting that 72% of 200 colic cases to feeding horses from the ground in sand turnout pens or were spasmodic. Spasmodic colic occurs when there are arenas (Walesby, 2004) (Figure 1). Signs of sand ingestion abnormal GT contractions due to an increase in bowel include weight loss, diarrhoea, and poor performance, so if movements (Frape, 2010). These abnormal movements you are concerned that your horse may have ingested sand, result in a cycle of painful spasms due to the GT being the recommendation is to seek veterinary and nutritional overactive, with spasms being either acute or lasting up advice (Kendal et al., 2008). to half an hour, and the cycle of spasms being over the period of a few hours. Spasmodic colic can occur at any point along the horse’s GT and cases are often mild. There are no specific nutritional risk factors associated with this form of colic, however high tapeworm infestation has been identified as a possible cause (Proudman et al., 1998). IMPACTION COLIC Another commonly seen form of colic is impaction colic. Impaction colic develops when the GT becomes blocked by a firm mass of ingesta (food that the horse has consumed Figure 1. Fields with limited grass cover increase the risk of horses and begun digesting), causing a build-up of fluid and gas consuming sand and dirt particles when eating. In areas with sandy soil which results in the GT becoming distended which is this intake of sand may be excessive leading to sand irritation or colic. extremely painful (Frape, 2010). Impaction colic can occur GAS COLIC in either the small intestine (SI) or the large intestine (LI), As horses are hindgut fermenters, microbes aid although it more frequently affects the LI. Impaction colic digestion in the caecum and large intestine, where fibre is in the SI is likely to be found in the ilium or at the iliocaecal digested (Frape, 2010). Gas colic is often found in the LI junction (the junction between the ileum and the caecum), due to excess gas being produced as a natural by-product whereas in the LI it can develop anywhere but normally of microbial fermentation in the LI, and occurs when the at the pelvic flexure where the large colon narrows and 16 17amount of gas being produced exceeds the amount of gas horse owner it is important to choose good quality feed and being removed (Frape, 2010). Gas colic cases can range forage to suit your horse’s nutritional needs. from mild to very severe where it is possible for the LI to Gas and impaction colic are almost always attributed to become distended and even twisted, causing excruciating nutritional factors (Southwood, 2013). Dehydration can be pain. Gas colic is often found to be feed related which is a common cause of impaction colic due to the combination discussed in the section on nutritional related risk factors. of reduced water intake and dry forage, therefore clean DISPLACEMENTS, STRANGULATIONS & TORSIONS fresh water should always be made available. Changes to These occur in the SI and LI and although they are less the horse’s diet, either in the amount of each feedstuff fed, common, they can be incredibly serious cases. It must be or the types of feed fed, should be made slowly to allow noted that the mild signs of colic listed in Table 1 may your horse’s microbial population to adapt to the nutrients be the early warnings that a more serious case of colic is that must be processed, and reduce the risk of colic (Garber about to develop, and therefore even mild signs must be KEY FACTORS TO REDUCE THE RISK OF COLIC monitored carefully. When a displacement occurs, a section • Get to know your horse’s normal vital signs of the horse’s intestines has moved to an abnormal area including their temperature, respiratory rate, within the abdomen, for example right dorsal displacement pulse and faecal consistency is when the large colon moves to sit between the caecum RE • Be able to spot the signs of colic and the right body wall causing obstruction and gas PAP distention (University of Liverpool, 2021). This form of • Feed a forage-based diet to promote healthy DE hindgut function colic more often affects larger breeds or recently foaled LC mares (Towcester Equine Vets, 2021). Strangulations result Y • Always ensure your horse has access to clean CE in the blood supply to a section of the intestine becoming fresh water R % compromised. This type of colic is potentially the most 0 • Mimic your horse’s natural trickle feeding 01 serious and life-threatening (Towcester Equine Vets, behaviours by feeding little and often N 2021), although if detected early the horse has a greater O • Make any dietary changes gradually to allow the D chance of survival but will require emergency veterinary E microbial populations in the horse’s GT time to TN care and surgery. Unfortunately, it is common that the I adapt RP horse will need to be euthanised if strangulation occurs • Make management changes gradually and as and is not treated quickly. Torsions are when the intestine stress free as possible twists on itself resulting in the blood supply being cut off • Avoid letting your horse graze in sandy areas to that area of the intestine. Broodmares in late pregnancy • Feed psyllium husks to horses with suspected and post-foaling have been found to be particularly prone sand burden or if grazing sandy areas to this form of colic, which can develop rapidly causing • Maintain a regular de-worming protocol fast deterioration of the horse in question, and death can occur anywhere from 4 to 24 hours from the onset of first • Keep up to date with your horse’s dental care symptoms (Rossdales Veterinary Surgeons, 2016). • The addition of pre and/or probiotics can help to support the microbial population in the GT (See FACTORS THAT MAY INCREASE THE RISK OF Pre and probiotics) COLIC OCCURING et al., 2020) (see Your horse’s gut: gastrointestinal structure NUTRITIONAL FACTORS and function in JEN issue 1). Such gradual changes apply A balanced and appropriate diet is key to a healthy horse, to all foodstuffs, including pasture and forage, and not just and unfortunately there are many nutritional factors from concentrate feeds. Other management changes should also the stable to the field that can increase the risk of colic. As a be made slowly, including gradually changing your horse 16 17from different pastures. This is particularly important if the system and promotes stretching of their back muscles. new pasture has ample grass coverage which horses may NON-NUTRITIONAL FACTORS rapidly ingest. Restricting the amount of grass consumed As previously highlighted, management changes should will reduce overeating and let your horse adapt to the new also be made gradually where possible, as changes can grazing. Spring and autumn grass can contain considerable cause horses to become stressed which may be linked to amounts of readily digestible carbohydrates and therefore increased incidence of colic (Purcell, 2005). Stress may can increase the risk of spasmodic colic, especially for horses who have had their grass intake limited or who have not been previously out at pasture (Purcell, 2005). Managing grass intake does not necessarily mean keeping horses stabled, as increasing pasture time can help to reduce the risk of recurring colic (Scantlebury et al., 2015) as it allows natural trickle feeding and promotes movement of ingesta along the GT. A high concentrate diet, particularly if it is high in starch and in the form of a pellet, can increase the risk of impaction and gas colic. Large amounts of carbohydrate cannot be digested within the SI and so may reach the LI, causing the pH to drop which disrupts the balance of the microflora (Purcell, 2005). Recommendations are for horses to eat no more than 1g of starch per kg of bodyweight (Frape 2010), meaning fibre should form the majority of the horse’s diet (Pagan, 2007). This fibre is gained from grass and preserved forages, most commonly hay and haylage. Straw can also be fed as a low-calorie fibre source, although consuming too much straw is associated with increased risk of impaction colic due to the straw being of low digestibility, meaning Figure 2. Horses with stereotypic behaviours, particularly crib biting, are thought to increase the risk of colic episodes. it takes longer to break down within the GT (Harris et al., 2017). Straw should be introduced to the diet slowly and also be caused by high workloads which in turn can lead can comprise up to 30% of the forage portion, although it to exhaustion from overworking, and thus dehydration and is not recommended for horses prone to colic and may not lack of appetite which all contribute to the risk of colic be suitable for all horses. Use of straw bedding should also (Frape, 2010). Stress may result in stereotypic behaviours, be avoided for such horses due to the risk of them eating such as crib biting and windsucking, which have been the bedding. found to increase the risk of colic episodes although further research is needed to determine the type and severity of Sand and soil consumption is found more in horses who colic associated with such behaviours (Malamed et al., are fed forage from the floor, especially in arenas or sand 2010) (Figure 2). Scantlebury et al. (2014) and Archer et paddocks, or in areas of sandy soil. To reduce the risk of al. (2008) also report that crib biting and windsucking sand consumption and sand colic, aim to keep horses' feed increase the risk of colic alongside weaving. Stress may and forage off the ground by using haynets, or feeders also be caused by box rest or reduced turnout or exercise, with a solid bottom. Hay feeders have the benefit of letting which has already been highlighted to increase the risk of horses eat with their head in a more natural, low position colic due to reduced movement of ingesta along the GT which promotes natural drainage of the respiratory 18 19(Towcester Equine Vets, 2021). Increased time in the stable the horse and maintain a healthy GT. may also reduce the overall amount of fluid consumed, SUMMARY as horses eat greater amounts of preserved forages which Our knowledge of colic and its risk factors has developed contain less moisture compared to grass. Such changes greatly over recent years to allow us to better understand, are particularly evident in autumn and winter when horses prevent and treat colic. Despite these advances, it may still may be stabled more due to weather variations. Diakakis be difficult for some owners to recognise the symptoms of & Tyrnenopoulou (2017) found a positive correlation colic, and the severity of the colic episode. As such, knowing between sudden temperature changes and the incidence of when to seek veterinary advice can be challenging, which colic, particularly between the colder and warmer seasons. is why it is recommended for owners to contact the vet as Maintaining good management practices and a parasite soon as colic is suspected, even for what seems like a mild control programme are also essential to reducing the risk of case, as it can quickly deteriorate into a more severe issue colic. Keeping stables and fields clean and removing faeces requiring emergency veterinary intervention. Each case should form a key part of parasite control programmes, should be assessed individually and whilst there are many as should testing for parasite burdens to identify animals possible nutritional and non-nutritional factors, owners requiring anthelmintic treatment (Frape, 2010). Dental care should consider all possible risks to reduce the occurrence should also be part of your horse’s routine management of colic. Aim to keep the horse’s diet as natural as possible RE and should not be overlooked as a potential contributing by feeding approximately 2% of their body weight per day PAP factor to the cause of colic. Maintaining a dental care with the majority of their diet comprising of forage. Avoid DE routine will ensure that food can be chewed properly overfeeding high carbohydrate feed and allow regular LC which reduces particle size and promotes breakdown of turnout. Finally, feeds should be offered in small amounts YCE ingesta (Purcell, 2005). Chewing also stimulates saliva and at regular intervals to mimic the natural trickle feeding R % production which helps to buffer the acidic stomach of behaviour of equids. 001 REFERENCES N Abutarbush, S.M., Carmalt, J.L., & Shoemaker, R.W. (2005). Causes of gastrointestinal colic in horses in western Canada: 604 cases (1992 to 2002). Canadian Veterinary Journal, 46(9): 800-805. O Archer, D.C., Pinchbeck, G.L., French, N.P., & Proudman, C.J. (2008). Risk factors for epiploic foramen entrapment colic: An international study. Equine Veterinary Journal, 40(3): 224-230. D Bowden, A., Burford, J.H., Brennan, M.L., England, G.C.W., & Freeman, S.L. (2020). Horse owners’ knowledge, and opinions on recognising colic in the horse. Equine Veterinary Journal, 52 (2) E 262-267. TN Bowden, A., England, G.C.W., Burford, J.H., Mair, T.S., Furness, W., & Freeman, S.L. (2017). Prevalence and outcome of conditions seen at out-of-hours primary assessment at two practices over a IR 3-year period (2011-2013). Equine Veterinary Journal, 49(51): 5-29. P Cohen, N., Gibbs P., & Woods, A. (1999). Dietary and other management factors associated with equine colic. Proceedings of the Annual Convention of the AAEP, 45:96-98. Diakakis, N., & Tyrnenopoulou, P. (2017). Correlation between equine colic and weather changes. Journal of the Hellenic Veterinary Medical Society, 68(3): 455-466. Frape, D. (2010). Equine Nutrition and Feeding, 4th Ed. Wiley-Blackwell, Oxford, UK. Garber, A., Hastie, P., & Murray, J.-A. (2020). Factors influencing equine gut microbiota: current knowledge. Journal of Equine Veterinary Science, 88: 102943. Gonçalves, S., Julliand, V., & Leblond, A. (2002). Risk factors associated with colic in horses. Veterinary Research, 33: 641-652. Greet, T.R.C., & Rossdale, P.D. (1996). The Digestive System. In: Rossdale, P.D. (eds.) Veterinary Notes for Horse Owners. Stanley Paul, London, UK. Harris, P.A., Ellis, A.D., Fradinho, M.J., Jansson, A., Julliand, V., Luthersson, N., Santos, A.S., & Vervuert, I. (2017). Review: Feeding conserved forage to horses: recent advances and recommendations. Animal, 11(6): 958-967. Kaneene, J.B., Miller, R., Ross, W.A., Gallagher, K., Marteniuk, J., & Rook, J. (1997). Risk factors for colic in the Michigan (USA) equine population. Preventative Veterinary Medicine, 30(1): 23-26. Kendal, A., Ley, C., Egenvall, A., & Brojer, J. (2008). Radiographic parameters for diagnosing sand colic in horses. Acta Veterinaria Scandinavia, 50(17). Malamed, R., Berger, J., Bain, M.J., Kass, P., & Spier, S.J. (2010). Retrospective evaluation of crib-biting and windsucking behaviours and owner-perceived behavioural traits as risk factors for colic in horses. Equine Veterinary Journal, 42 (8): 686-692. Mcgovern, K.F., Baldon, B.M., Fraser, B.S.L., Boston, R.C. (2012) Attempted Medical Management of Suspected Ascending Colon Displacement in Horses. Veterinary Surgery. 41 (3): 399-403 Pagan, J.D. (2007). Causes, risks of colic explained. Feedstuffs, 79(7). Proudman, C.J. (1992). A two year, prospective survey of equine colic in general practice. Equine Veterinary Journal, 24(2): 90-93. Proudman, C.J., French, N.P., & Trees, A.J. (1998). Tapeworm infection is a significant risk factor for spasmodic colic and ileal impaction colic in the horse. Equine Veterinary Journal, 30(3): 194-199. Purcell, K. (2005). An ounce of prevention: Feeding management to minimize colic. Advances in Equine Nutrition Volume 3: 121- 126. Rossdales Veterinary Surgeons (2016). Published on the Internet; [Accessed 26 July 2021] Scantlebury, C.E., Archer, D.C., Proudman C.J., & Pinchbeck, G.L. (2011). Recurrent colic in the horse: Incidence and risk factors for recurrence in the general practice population. Equine Veterinary Journal, 43(39): 81-88. Scantlebury, C.E., Archer, D.C., Proudman C.J., & Pinchbeck, G.L. (2015). Management and horse-level risk factors for recurrent colic in the UK general equine practice population. Equine Veterinary Journal, 47(2): 202-206. Scantlebury, C.E., Perkins, E., Pinchbeck, G.L., Archer D.C., & Christley, R.M. (2014). Could it be colic? Horse-owner decision making and practices in response to equine colic. BMC Veterinary Research, 10 (S1). Southwood, L.L. (2013). Practical Guide to Equine colic. Wiley-Blackwell, Chichester, UK. Towcester Equine Vets (2021). Colic. Published on the Internet; [Accessed 25 July 2021] University of Liverpool (2021). Colic types and causes. Published on the internet; [Accessed 25 July 2021] Walesby, H.A., Blackmer, J.M., & Berthelot, A. (2004). Equine Sand Colic. Compendium on continuing education for the practicing veterinarian, 26(9): 712-719. 18 19A holistic approach to supporting your horse’s mobility Dr. Stephanie Wood, PhD Equine Nutrition, PgDip, BSc (Hons), RNutr (Animal), R.Anim.Tech Stiffness, lameness, shortened stride and reluctance to horse’s musculoskeletal system and their overall mobility. move forward are all signs that our horses are not feeling MANAGEMENT comfortable when they move, and that they are likely to Equids have evolved with movement linked to eating be experiencing some degree of discomfort (Dyson, 2016; (Stephens & Krebs, 1986), taking a few mouthfuls in one Dyson et al., 2020). Whether your horse is retired and area then taking a step or two to move onto a new area. Often spends their day moving around their field, or competing our focus is on ensuring our horses satisfy their behavioural at the highest level, pain-free, easy movement is desired. and nutritional needs to graze for 12 to 18 hours each day, Achieving this can be challenging, especially when we whilst the need for movement is largely overlooked. Time think about how the horse’s large body frame, lack of in the field or turnout area allows free movement and muscle in the lower limbs and great athletic ability make promotes circulation of blood and lymph that transport their limbs and joints vulnerable to injury and wear and oxygen and nutrients to the cells and tissues and remove tear. These same factors can also lead to muscle, tendon and waste material from the body (Frick, 2010). Free movement ligament issues as a result of repetitive movements, even also activates the musculoskeletal system without the in those who lead a more sedate lifestyle. Conformational constraints or weight of a rider, helping to maintain fitness faults, favouring one rein over the other, and poor execution and keep bones, joints and muscles metabolically active. of movements when exercised can also lead to muscle Studies comparing the effects of constant stabling, stabling tightness and imbalances, and as a consequence muscle combined with exercise, and constant turnout to pasture, on atrophy (wastage) (Dyson, 2016). Providing appropriate fitness levels and bone density in horses, repeatedly show management and nutrition combined with a suitable that pasture turnout enables horses to maintain their bone density and level of fitness, and that immobility due to exercise regime will help to maintain and support your Dr Stephanie Wood, PhD, PgDip, BSc (Hons), RNutr (Animal), R.Anim.Tech Stephanie has many years’ experience managing horses in both a private and professional capacity. During her time caring for different horses she developed a keen interest in nutrition which lead her to gain her undergraduate degree in Equine Science from Aberystwyth University, followed by a PhD in Equine Nutrition from the Royal (Dick) School of Veterinary Studies at the University of Edinburgh. These academic achievements are recognised in her certifications as a Registered Animal Nutritionist and Registered Animal Technologist. Stephanie has a passion for helping others to learn and understand which was utilised in her positions as Senior Equine Technologist where she developed training and educational material for the equine industry, and as Senior Lecturer where she tutored the next generation of equine professionals. Stephanie’s passion for helping others combined with her hands-on industry experience and technical knowledge enable her to support owners with practical advice and guidance in her role as Director of Science and Nutrition at Feedmark. 20 21constant stabling reduces both of these factors (Nielsen & mobility and performance due to increased strain on their Spooner, 2008; Graham-Thiers & Bowen, 2009; Logan et joints, which is magnified in high impact activities such as al., 2019). Free movement may also help with maintaining jumping (Clayton, 1997; Rendle et al., 2019). The more insulin sensitivity as low-intensity exercise has been weight travelling through the limbs, the greater the wear shown to increase the response to insulin in horses and and tear on the joints and soft tissues supporting the joints. ponies (Bamford et al., 2019), although an earlier study Research in overweight dogs (Marshall et al., 2010) and humans (Bliddal et al., 2014) with reduced mobility due to limb osteoarthritis showed that a reduction in body weight TOP 5 TIPS FOR EFFECTIVE STRETCHES to a healthy weight, lead to improvements in mobility • Know what you are trying to stretch and why! and a reduction in lameness scores. Jansson et al. (2021) • Take it slow – quality is better than quantity. recently demonstrated the effect of greater body fat levels • Look for cheats. Look at your horse’s positioning, on performance, with horses having greater asymmetry in consider using walls/corners to support the stretch their movement when their fat stores increased. The same but make sure they don’t become ways to avoid study also confirms that excess body weight increases doing the movement properly. the work the respiratory and circulatory systems have to • Reward appropriately – be careful not to over perform when horses exercise, leading to a reduction in feed or cause nipping and behavioural problems! R performance capacity and the likelihood of earlier onset EP • Ask for help from a suitably qualified professional A fatigue (Jansson et al., 2021). In view of these findings, P if you are unsure. D prevention of excess body weight in the first instance is EL ideal, although this can be difficult in horses and ponies CY found turnout alone to be insufficient to influence insulin C that seem to thrive on fresh air and preferentially store fat. ER responses (Turner et al., 2011). As such, the effect of turnout The benefits of weight loss on mobility and performance %0 on maintaining fitness and insulin responses will be shaped 0 however do show how even a slight decrease in body 1 by how active your horse is when allowed free movement. N weight supports joint health. O For horses without any health issues, management regimes DE should aim to provide frequent and regular opportunities TNI for free movement, although it is recognised that for some RP animals such opportunities need to be balanced with other requirements. Animals with injuries, or recovering from injury, will often require their movement to be controlled for a period of time to allow recovery, whilst those who are overweight or prone to laminitis will usually have their grass intake controlled which may in some circumstances Figure 1. Performing baited stretches with your horse increases require restricted turnout. In such circumstances, flexibility and range of movement, supporting their overall mobility. maintaining mobility is even more challenging although stable management practices such as feeding at floor level PHYSIOTHERAPY which requires horses to stretch their muscles, is a simple Some horses may also benefit from physiotherapy practice that supports muscle health whilst also encouraging to help maintain or improve joint and muscle function. natural drainage of the respiratory system. Adding stretches Physiotherapy helps to restore movement and function to your horse’s routine may also be useful in supporting when an individual is affected by injury, illness or disability, their mobility. with treatment focusing on restoring painless, optimal function, and prevention of loss of function (Tabor, 2021). Maintaining our equids at a healthy weight is also For some equids, building regular physiotherapy sessions important for their mobility. Excess weight reduces their 20 21into their management regime can help them to perform at tailored to the purpose of the stretching, and your horse’s specific requirements. Regardless of when stretching takes their best or manage ongoing issues, whereas for others less place, it is important that the muscles are warmed up prior frequent, periodic sessions are more appropriate. The best to stretches being performed. Physically warming the option for your horse should be decided through discussions tissues increases the extent to which the tissues can stretch, with your vet and physiotherapist who should work extending how far the stretch can go and helping to reduce collaboratively to support your horse. One activity that is the risk of overstretching and damaging the tissues (Frick, often promoted as suitable for owners to perform with their 2010). See Role of physiotherapy in supporting mobility. horses is stretching. Stretching seeks to increase the horse’s flexibility and elasticity with the overall aim of reducing EXERCISE pain and the strain on soft tissues, and increasing joint Any exercise sessions should be appropriate for the range of motion (Frick, 2010). Active stretches are where horse and rider’s level of training and fitness to ensure the horse moves its own body through muscle contraction the body can respond to what is asked of it. Preparation and can be performed during groundwork or when ridden. for the main exercise activity through appropriate warm- Baited stretches which use a treat or bait to encourage the up procedures has been shown to be extremely important horse to stretch to a certain position, are commonly used in human, canine and equine athletes (McCutcheon et al., active stretches, encouraging the horse to stretch its head 1999; Steiss, 2002; Racinais et al., 2017). The warm-up and neck down or to the side with the aim of stretching functions to transition the body from the resting state to the neck and back muscles and engaging the abdominal an active state and, through this transition, reduce the risk muscles (Figure 1). Passive stretches are where a person of injury and optimise performance (Steiss, 2002; Pösö et moves the horse’s body for them and is commonly seen in al., 2008). The term warm-up is literal, as muscle activity groundwork when the horse’s limbs are stretched forwards. increases muscle temperature leading to a rise in core body Due to the degree of stretch being decided by the person temperature (Racinais et al., 2017). The rise in muscle and performing passive stretches, they are not recommended core temperature increases elasticity of muscles, tendons unless training on how to perform them correctly is received and ligaments, and is thought to help prevent injury by from a qualified professional (personal communication – increasing support for joints and reducing excessive strain Jessica Seeley, JKG Physiotherapy, UK). Stretching can of these soft tissues (Pösö et al., 2008; Racinais et al., be performed before exercise, between exercise sessions 2017). Movement also promotes stretching of muscles and lubrication of joints. The joints of the horse’s limbs and after exercise, although stretching routines should be Jessica Seeley, BSc (Hons), MSc Vet Phys, MCSP, ACPAT Cat A Jessica qualified as a Physiotherapist from the University of Southampton in 2011, and after a short period of working in the NHS she then went on to complete a Masters in Veterinary Physiotherapy at the University of Liverpool. Jessica now runs a busy clinic in Hampshire (JKG Physiotherapy, www.jkgphysiotherapy. com) treating both horses and riders and teaches Pilates for horse riders. She has a specialist interest in horse and rider biomechanics, and aims to work with both as a partnership to maximise health and performance for all. Jessica is an ACPAT qualified Veterinary Physiotherapist as well as being a member of the RAMP Register. 22 23THE ROLE OF PHYSIOTHERAPY IN SUPPORTING MOBILITY Jessica Seeley, BSc (Hons), MSc Vet Phys, MCSP, ACPAT Cat A, JKG Physiotherapy IMPORTANCE OF MOVEMENT Movement is important for all horses and ponies of all ages but is particularly important for younger animals. If horses cannot go in the field or turnout area, then long lining or lungeing on large circles enables the horse to move. This movement is important for the horse to develop their own balance and to move their joints through their full range of movement. By allowing them time in the field or through groundwork, we can observe how they move without the rider influencing them. Elite riders are very good at influencing the horse’s movement, so watching the horse’s natural way of going can help to identify imbalances and guide improvements and reduce the risks of injury. IMPORTANCE OF WARMING-UP The warm-up is often underestimated when preparing our horses for more demanding exercise. The warm-up needs to be tailored to what is appropriate for the individual horse, the setting of the warm-up and whether the horse has come straight out of the stable, trailer or field. Some horses benefit from a canter before they go on to do trot work, whilst others work better progressing through the paces. A warm-up of 10-15 minutes should be enough before the horse is asked to perform more demanding work. If possible, discuss with your physiotherapist the duration of the warm-up and what movements should be included to support your horse’s movement and benefit their training. BENEFITS OF PHYSIOTHERAPY Physiotherapy is appropriate for horses of all ages and stages of life as it focuses on providing support to maintain movement. For working horses, physiotherapy focuses on supporting them to develop and use the right muscles for the work they are asked to perform. This is particularly important for young horses that may not have the muscle development or strength required at the start of R training. For sport horses, four and five years are crucial ages as this is when we ask for more from their work. Regular physiotherapy EP sessions allow any development issues to be identified early and supportive actions to be put in place. This is a preventative tactic AP that reduces the likelihood of the issue escalating into something more difficult to rectify. D For older horses or those that are retired, physiotherapy is also beneficial. Older horses with reduced muscle density may have a EL reduced range of movement therefore physiotherapy helps to improve this and maintain their mobility. CY BENEFITS OF STRETCHING CE Stretching helps to increase joint range of movement, lengthen muscles and activate the horse’s core muscles. Baited stretches R allow the horse to learn their full range of movement and encourage abdominal activation which increases spinal range of movement. %00 Stretches performed before exercise aim to prepare the muscles and joints for exercise, whilst stretches after exercise support 1 recovery. What is important is that the muscles are warm before performing stretches as this maximises the stretch and reduces the NO risk of injury. DE If your horse is stiff, then stretching before exercise is beneficial as it encourages movement of joints and muscles and increases T blood to these structures. Stretches before exercise will not be as deep as if performed after exercise, but they can be useful for NIR helping to loosen off a stiff horse. I would not recommend stretching the horse’s front legs before the horse is ridden as this can pull P the skin in front of the girth which can then restrict movement as the skin has nowhere to go. Also, you are unlikely to be aiming for the front legs to move that far forwards when the horse is ridden so that stretch is not that beneficial. If your horse has worked hard or their training session focused on specific movements, then doing stretches afterwards can be really beneficial in helping recovery. I also recommend stretches for older horses on their days off to help keep them moving and mobile. What is important is that you know why you are doing the stretches and which muscles and joints you are aiming to support. CONSIDERATIONS WHEN STRETCHING Owners should ensure they are using a qualified practitioner for whatever supportive therapy they choose. You can find qualified practitioners on the Register of Animal Musculoskeletal Practitioners (RAMP, or The Association of Chartered Physiotherapists in Animal Therapy (ACPAT, Your professional should advise what stretches are suitable and beneficial to your horse and how to perform them. Horses are not going to move to a position that they find painful or uncomfortable to reach a treat in baited stretches, so they are relatively safe as the horse is in control of how far they stretch, although you still need to ensure that you are not asking them to stretch beyond their ability. Baited stretches are unlikely to cause any harm to your horse, but they may also not be doing any good if performed incorrectly. Leg stretches which are performed by the owner should be performed after being demonstrated by your practitioner to ensure the leg is not pulled at an angle or direction that could cause damage. I always show owners how to perform the stretches and ask them to demonstrate them back to me to ensure they are performed correctly. If you want to incorporate stretches into your horse’s routine, then start with advice from your practitioner as every horse is different and stretches should be specific to the horse’s requirements. 22 23are synovial joints that contain a joint cavity filled with allowing the body to slowly return to a near resting state. lubricating synovial fluid. This fluid is important for By continuing with low intensity exercise blood continues preventing friction between the bones within the joint. to circulate, removing the waste products of metabolism Flexion of the synovial joints increases pressure within the from the muscles and lowering body temperature through joint cavity, causing an outflow of synovial fluid from the the dissipation of heat (Steiss, 2002). What activity is joint. Extension of the joint reduces pressure leading to an performed during the warm-down will again depend on the inflow of fluid into the joint cavity (Levick & McDonald, individual horse, exercise performed and environment. In 1995). As such, movement is integral to joint lubrication cooler conditions the focus will be on returning heart and and health. When movement is limited, either due to respiratory rates to resting without allowing the horse to being stabled for long periods or transportation, horses become cold, whereas in hot conditions rapid cooling is can develop filled legs due to the lack of joint flexion and used to quickly reduce body temperature whilst the horse’s extension, and therefore lack of synovial fluid flow, leading heart and respiratory rate gradually decrease. to the fluid pooling in the lower limbs (Bertone, 2008). NUTRITION The warm-up also triggers responses from the Supporting mobility through nutrition focuses on cardiovascular and respiratory systems. Increases in heart providing key ingredients in the diet. Ingredients to support rate and stroke volume (volume of blood ejected per beat joints have been fed for many years, with joint products from the left or right ventricle) increase cardiac output, and being the most common supplement fed to horses (Agar the spleen is triggered to contract and release red blood et al., 2016; Murray et al., 2018), whereas ingredients cells (RBC) into the circulation (Poole & Erickson, 2008). specifically to support muscle function, development and Blood vessels serving the muscles dilate whilst those to recovery are a more recent addition to the equine feed other organs constrict, leading to preferential blood flow and supplement market. Joint and muscle supporting to the skeletal muscles (Pösö et al., 2008). The horse’s ingredients are not replacements for correct training or respiratory rate increases as does the amount of air inhaled appropriate management, but instead have complementary per breath (tidal volume), which when combined with roles alongside a balanced diet, appropriate management the cardiovascular responses, increase oxygen supplied and tailored training and exercise. to the muscles (Ainsworth, 2008). Onset of exercise also JOINT STRUCTURE triggers cell metabolism to switch from energy storage to To understand how certain ingredients support the horse’s energy utilisation (Pösö et al., 2008). These physiological joints we need to understand the structures comprising the responses to the onset of exercise show how warming up joints. The joints we are most often concerned with for our horses prepares them for more demanding activity. our horses are the synovial joints, which generally, but Recommendations for warm-up protocols are lacking not always, have a wide range of movement and form as they are specific to the individual horse, activity the pastern, fetlock, knee, elbow, hock, hip and sacroiliac requirements and environmental conditions. The balance joints. All bone surfaces that articulate have a cartilage between preparing the body for more demanding exercise covering (Figure 2). In the horse’s limbs this articular without draining energy sources can be challenging, cartilage is hyaline cartilage, and its role is to reduce especially in warmer climates as we have seen recently friction between the bones and absorb shock (Dyce et al., with the Olympics in Tokyo. In addition, having too long a 1996; van Weeran & Brama, 2001). Hyaline cartilage is period between the warm-up and onset of more demanding made of cartilage cells (chondrocytes) and an extracellular exercise reduces the benefits of the warm-up if the body matrix that acts like a frame structure around the cells. begins to cool down (Pösö et al., 2008). For horses The extracellular matrix is made up of collagen fibrils competing or required to perform specific activities there (mainly type II) (~15%), proteoglycans (~10%) and water is also a need to prepare them mentally for the tasks ahead. (~75%). The collagen fibrils are anchored within calcified The warm-down period is also important for any horse, 24 25cartilage that lies beneath the hyaline cartilage and adjacent results, this is not currently a routine treatment. As such, to the subchondral bone (van Weeran, 2014), securing reducing articular cartilage degeneration is preferred, with the cartilage to the bone. The chondrocyte cells produce joint supporting ingredients being one method of supporting the proteoglycans, which consist of a central protein the cartilage. core and one or more glycosaminoglycan (GAG) side The synovial membrane completes the inner lining of the chains (van Weeran & Brama, 2001). The most important joint capsule, reaching from one articular cartilage to the other (Figure 2). The synovial membrane is only a few cells thick and contains type A cells that have a protective role in the joint, removing cell debris, and type B synoviocytes that synthesise HA (Bertone, 2008; van Weeran, 2014). Both cells are also able to produce molecules involved in inflammation which is associated with common joint diseases such as osteoarthritis (van Weeran, 2014). The synovial membrane contains nerves, capillaries and lymphatic vessels, meaning it provides a pathway for the delivery of oxygen and nutrients to the joint structures, RE including the articular cartilage, and the removal of waste PAP products (Bertone, 2008). The synovial membranes have a Figure 2. Diagram of a healthy synovial joint (left) and an inflamed DE sieve-like action that regulates the molecules entering the synovial joint (right). LCY synovial fluid. As a result, the molecular size of ingredients C proteoglycan in articular cartilage is aggrecan which E fed to support joint function must be small enough to pass R has a large number of GAG side chains which comprise % through, although molecules up to 10kDa are able to pass 00 either Chondroitin sulphate or keratin, with Glucosamine 1 from the blood into the joint cavity and synovial fluid (van N forming part of the keratin (van Weeran & Brama, 2001). O Weeran, 2014). Aggrecan molecules attach to Hyaluronic acid (HA), DET Synovial fluid is said to be produced by the synovial another important proteoglycan produced by chondrocytes NIR membrane, however it is more correctly termed an (Mahmoud, 2021). Aggrecan connects to the collagen P ultrafiltrate of plasma (van Weeran & Brama, 2001; network both directly and via HA molecules. The result of Bertone, 2008), meaning that blood plasma has been these interlinked complex structures is articular cartilage filtered through the synovial membrane to remove high that is able to withstand stretching (tensile strength) due molecular weight proteins. Hyaluronic acid is added to to collagen, and resist deformation under pressure due the fluid by synoviocytes to produce a fluid that is highly to proteoglycans (Bertone, 2008). viscous (thick, sticky) and yellow in colour (van Weeran, Articular cartilage has no blood or nerve supply, 2014). This viscous fluid facilitates smooth movement of and instead receives oxygen and nutrients via diffusion the articular cartilages, thus has a lubricating action. It from the synovial fluid, synovial membrane, and joint also provides a medium through which oxygen, nutrient capsule (Bertone, 2008). This lack of blood supply makes and waste product exchanges occur. The composition of regeneration of articular cartilage almost impossible in the synovial fluid is controlled by the synovial membrane, adult horses, although there is some capacity for repair therefore in cases of joint damage or disease it is likely in young animals (van Weeran & Brama, 2001). Due to that substances promoting inflammation (mediators and this poor capacity to repair, treatment options for articular cytokines) are released by the synovial membrane into the cartilage damage are limited. Studies into the effectiveness synovial fluid, where they exert their damaging effects on of stem cell treatment for articular cartilage repair in equids the articular cartilage (van Weeran, 2014). are ongoing, and although there have been some favourable 24 25The joint capsule is a fibrous membrane that forms the and may even result in cell damage. Neil et al. (2006) outer layer of the joint. Its purpose is to provide support also performed an in vitro study using extracted equine to the joint through attachment to the outer surface of the cartilage and tested the effectiveness of either Glucosamine articulating bones. Ligaments are formed by bundles of this or Chondroitin sulphate on the activity of enzymes fibrous membrane and provide further strength and support (matrix metalloproteinases [MMPs], aggrecanases) and to joints (Dyce et al., 1996). inflammatory mediators (nitric oxide, prostaglandin E2) associated with osteoarthritis. They found that Glucosamine JOINT SUPPORT was particularly effective in reducing enzyme activity and From the review of joint structure, it is easy to see why had a limited effect on reducing inflammatory mediators, ingredients such as Glucosamine, Chondroitin sulphate and however there were no reported effects of Chondroitin HA could support joint health, as they are integral to key sulphate. The authors attributed the lack of effect of joint structures. It would be easy to assume that providing Chondroitin sulphate to a too low dose, highlighting the a dietary source of these compounds could ‘top-up’ the challenge of extrapolating results from in vitro studies to levels within the joint structures and therefore help to the live animal. maintain joint function (Laverty et al., 2005). However, the mechanisms of these substances are not that straight One point for consideration when compounds are forward, with modes of action being related more to administered to the live animal in oral form is the slowing the rate of joint degradation through inhibition of amount of compound absorbed by the animal, known cartilage degrading enzymes and inflammatory mediators as its bioavailability. A criticism of oral Glucosamine (Dechant & Baxter, 2007), and not the repair of joint tissues and Chondroitin sulphate given to horses, are their low as we remember that articular cartilage cannot regenerate absorption rates which are approximately 5-9% for in adult horses. Glucosamine and 32% for low molecular weight (8kDa) Chondroitin sulphate (Du et al., 2004; Laverty et al., Glucosamine and Chondroitin sulphate are the most 2005; Meulyzer et al., 2008). Indeed, a study by Welch et researched joint supporting ingredients although the al. (2012) found there to be no increase in Glucosamine number of studies using horses as the subject are limited, or Chondroitin sulphate concentrations in the plasma of most likely due to the high cost of performing research six horses fed Glucosamine and Chondroitin sulphate, on large animals, and the ethical considerations of using suggesting that these compounds undergo some form of animals in research. An alternative to using live animals are digestion prior to being absorbed which could influence in vitro studies in the laboratory, using extracts of equine their effectiveness. It must be highlighted however, that joint tissues. Fenton et al. (2002) used articular cartilage low bioavailability is not necessarily an issue if adequate from horses’ carpal (knee) joints and induced cartilage amounts of a compound are fed to exert an effect. It is also degradation as a model for osteoarthritis. They tested vital that compounds reach the target tissues, which in the the effect of three levels of Glucosamine hydrochloride case of joint support is the synovial fluid. Increased levels (HCl) on the articular cartilage and found that enzymes of Glucosamine have been detected in synovial fluid after associated with degradation of cartilage were reduced oral administration of clinically recommended doses to by the Glucosamine, with the greatest effects seen at the horses (Laverty et al., 2005; Meulyzer et al., 2008). Orally higher doses. The same study also reported a reduction in administered Chondroitin sulphate has also been detected nitric oxide and prostaglandin E2 which are both linked to in the synovial fluid of dogs, rats (Palmieri et al., 1990) and the development of osteoarthritis. Such results show that horses (Moreira et al., 2019). Glucosamine and Chondroitin Glucosamine HCl has a potentially protective action on sulphate are frequently administered in combination to joint cartilage, however the authors acknowledged that enhance their efficacy (Orth et al., 2002). the high Glucosamine dose required to exert an effect in vitro, is unlikely to be suitable for use in the live animal Hyaluronic acid and Methyl sulphonyl methane (MSM) 26 27are also fed to support joints. As a constituent of articular feeding just Chondroitin sulphate, also reported favourable results with supplemented horses having greater joint cartilage and synovial fluid, HA supplementation supports flexibility and stride length and reduced lameness scores joint function by enhancing synthesis of chondrocytes, after supplementation for 30 days, compared to horses in HA and proteoglycans and by inhibiting inflammatory the control group. mediators and enzymes involved in articular cartilage degradation (Gupta et al., 2019). Hyaluronic acid has been A longitudinal study by Rogers (2006) used the number shown to have good bioavailability in rats, dogs and horses of HA and steroid injections required in horses’ joints (Pierce 2004; Balogh et al., 2008) and to reach articular as a measure of how effective an oral Glucosamine and cartilage and synovial fluid. Methyl sulphonyl methane Chondroitin sulphate supplement was at maintaining is a sulphur-containing compound fed for its antioxidant mobility. Ten horses received the supplement for six years and anti-inflammatory effects (Butawan et al., 2020). The and the number of joint injections required was monitored body readily uses the sulphur from MSM in connective over this period. The number of injections over the study tissue, and it is also thought to contribute to articular period were compared with the number required in the two cartilage structure, although the absorption of MSM varies years prior to the study, with results showing the average with species. Methyl sulphonyl methane has been shown number of injections required by horses was less when to reduce pain associated with osteoarthritis by blocking consuming the supplement. Monitoring horse responses to R the pain response in nerve fibres (Gupta et al., 2021). The E supplementation over a prolonged time is commendable, PA majority of research on MSM has focused on humans P however mobility and joint health could have been affected D however the antioxidant, anti-inflammatory, and analgesic E by multiple factors (workload, age, medication) which LC properties make it a common addition to horses’ diets, were not monitored or recorded, therefore attributing a YC either individually or in combination with the previously E reduction in joint injections and maintenance of mobility to R mentioned joint supporting ingredients. % the supplement alone is inappropriate. 001 Studies assessing the efficacy of joint supplements for A weakness of these early studies is that the people NO supporting movement in live horses have shown variable performing the assessments were aware of which horses DE results. Comparison between studies is difficult due to had been supplemented, and so were not blinded to TNI different study designs and durations, the use of horses treatment being tested. This lack of blinding may have RP with healthy joints, artificially induced joint disease, and influenced assessments of mobility and therefore results those with naturally occurring joint disease, the use of gained. A further weakness of the studies by Hanson et al. different ingredients and feeding levels, and different (1997) and Rogers (2006) was the lack of control group assessment parameters. Studies published in the 90’s which would have allowed comparison with animals feeding Glucosamine and Chondroitin sulphate to horses that had not received the treatment, and therefore greater used measurements of joint flexion, lameness score, stride confidence that the results gained were attributed to length and x-rays to determine the supplement efficacy. the treatment. More recently blinded studies have been White et al. (1994) found no difference in these parameters undertaken to determine the effect of joint supplements between supplemented and control horses, whereas on mobility which is a positive step forwards for equine Hanson et al. (1997) feeding Glucosamine and Chondroitin science. Murray et al. (2014) reported improvements in sulphate to 25 horses reported a significant increase in lameness scores assessed in a straight line and on a circle joint flexion and stride length, reduction in lameness in mature horses administered a supplement containing score after two weeks of receiving the supplement, and a Chondroitin sulphate, Glucosamine, Vitamin C, MSM and further improvement in lameness score after four weeks the long chain fatty acid Docosahexaenoic acid (DHA). of supplementation. This study however did not include a This study also used the more objective assessment of joint flexion using high speed video gait analysis and reported control group for comparison. Dorna & Guerrero (1998) 26 27(vitamins and minerals) for enzymatic and metabolic a significant increase in hock flexion in horses consuming processes. The high protein level in muscles can lead to a the supplement. Forsyth et al. (2006) had previously used focus on dietary protein supply, when the focus should be this technology to assess the effect of a Glucosamine and on providing a diet that meets all nutrient requirements. It Chondroitin sulphate supplement fed at manufacturer levels is correct that horses performing more exercise (intensity to older horses (15-35 years), on gait parameters. Elbow, and/or duration) have higher crude protein requirements stifle and hind fetlock joint range of motion increased than horses with lower exercise demands due to increased significantly in supplemented horses after eight weeks and muscle development, tissue repair and nitrogen losses in continued until the end of the trial (week 12). There were sweat (NRC, 2007; Pratt-Phillips & Lawrence, 2014). also trends for greater range of motion in knee, hock and However simply feeding more protein may not be the front fetlock joints, although these were not statistically answer and feeding protein in excess of requirements has significant. Supplementation also increased stride length no additional benefits in exercising horses (Pratt-Phillips & by week eight, which continued until the end of the trial. Lawrence, 2014). The amino acid content of the protein fed In contrast, Higler et al. (2014) assessing the effect of a is important, with protein containing essential amino acids Glucosamine, Chondroitin sulphate and MSM supplement on older horses (25-33 years), found no difference between the stride length, knee flexion, fetlock extension and hock range of motion of horses supplemented for three months and those receiving a placebo for the same amount of time. Differences in results highlight the difficulties of assessing supplement efficacy and standardising trials. Studies clearly show that joint supporting ingredients have effects on joint tissues when tested in vitro, but more research is needed to conclusively determine their effect in the live animal. Whilst research is ongoing the decision on whether to feed joint supplements is up to the individual horse owner. Another area where there is evidence to support beneficial effects on mobility is the use of substances with anti-inflammatory properties such as Devil’s Claw (Axmann et al., 2019), Figure 3. The feeding of certain ingredients can help to support muscle function and recovery and can be particularly beneficial to horses Boswellia (Reichling et al., 2004; Sengupta et al., 2008 performing more strenuous exercise. – see Ingredient spotlight: Boswellia in JEN issue 1) and Omega-3 fatty acids. Chronic inflammation is known to be (amino acids that cannot be made by the horse) classed as a major contributor to joint degeneration therefore feeding high-quality protein. Lysine is the first limiting amino acid ingredients that can counteract inflammation can be meaning it is the amino acid most likely to be deficient beneficial, with such anti-inflammatory effects also being in the diet and that limits utilisation of other amino acids beneficial to ligament, tendon and muscle health. (McDonald et al., 2011). Lysine requirements rise with increasing exercise demand. If the diet contains protein MUSCLE SUPPORT sources with low Lysine content, then more of the protein The foundations for muscle development and effective source will need to be fed to meet Lysine requirements. function are providing appropriate nutrients for muscles The requirement for other essential amino acids is also to utilise, and activation of muscles through appropriate likely to increase with higher exercise demands, although exercise. The diet is therefore key and must provide energy these requirements have not been quantified at present. for muscle contraction and cellular activity, protein for Soya bean meal, Canola meal, legumes and Spirulina are development and repair of muscle tissue, and micronutrients good sources of Lysine and other essential amino acids and 28 29OPTIMISING MOBILITY AS A PROFESSIONAL DRESSAGE RIDER Stephanie Taylor, international dressage rider and breeder competing at Grand Prix level with her string of horses, discussed with our Director of Science and Nutrition, Dr. Stephanie Wood, how she optimises her horses’ mobility. How important is allowing your horses to maintain their mobility? Maintaining the horse’s mobility is very important and being able to turn horses out is a key concern. We have purpose-built turnout pens that we use when field turnout is not suitable. The turnout pens mean they can spend time out of the stable, stretch their legs and also be sociable over the fence with their friends. I don’t use a horse walker very often due to the additional pressure the repetitive movement can place on the horse’s limbs. For this same reason I don’t lunge very much, and instead prefer to hand walk or graze the horses if they cannot get out in the field. Do you incorporate specific mobility support into your horses’ management routine? Physiotherapy forms a key part of the horses’ routine with sessions being every 2-3 months depending on the individual horse’s requirements. Before a competition the horses may have an additional session to release any tension, although we avoid deep tissue work prior to competition. I also have physiotherapy sessions with the same therapist along with personal training sessions twice each week. These sessions enable identification of issues in me which may then cause issues when riding. Having the physiotherapist for both me and my horses enables a joined up, holistic approach. After competition the horses are hacked rather than having a day off. This helps to keep them moving after the travelling and more intense exercise required for competition. The hacking provides light exercise which they enjoy and is actually part of their normal R training regime. I like to provide variety in the horses’ training as this keeps them interested and avoids over straining certain muscles EP and joints. The horses will usually have one day off each week, and then stretching sessions, schooling, hacking, go to the gallops and AP they also jump or do pole work once a week. Schooling can still take place outside of the arena, for example practicing flying changes DE on the gallops, which the horses enjoy much more than in the arena. LC The horses also go to the water treadmill once a week which has really helped to improve their strength without placing strain on YC their joints. One of my horses struggled to walk in a straight line which only became evident on the treadmill when he needed the ER support of the side to help him. He has increased in strength and is now much straighter and I can feel the difference when he is ridden. %0 I also have a solarium which they go under every day during winter to warm up their muscles and I find this really helps. In contrast, 01 I like to ice their legs if they have worked hard, or the ground is particularly hard, as I feel it helps to reduce any inflammation. NO Do you aim to keep your horses’ management the same when at competitions? DE Where possible I aim to keep their management the same. Turnout is not usually possible so we will hand walk them four times a TN day to keep them moving and feed plenty of forage. I also keep their warm-up routine the same as much as possible. IRP What importance do you place on warming your horses up and what would a normal warm up consist of? The warm-up is just as important as the rest of any training session. I tend to ride in the morning, so the horses are coming from their stables, so I focus on plenty of stretching. I like to walk for 10 minutes on a long rein then I prefer to move into canter with me off their backs as this encourages their back muscles to stretch and engagement of their hindquarters. For the lazier horses I’ll do some faster work to get them engaged, then work towards collection. After the initial warm-up I’ll do lots of walk and trot transitions and stretching laterally as well as forwards, then I progress to the more focused work. In all of the sessions there are regular walk breaks. There is more stretching at the end as a warm-down and relax, which could take place on a short hack. My training sessions are generally about 30 minutes, with sessions with my trainer being slightly longer at 45 minutes. I go with the ethos of quality is better than quantity, so achieving good results is better than working the horses for a certain length of time. Longer sessions are not necessarily more effective! Do you do stretches with your horses? Yes, I work with my physiotherapist to know what is most appropriate for each horse. I stretch one horse before exercise as they get quite tight in the base of their neck, so the stretch is there to help ridden performance. The other horses I stretch after work as the stretch is focused on recovery. I think it is important to know the purpose of the stretches you are performing, which is guided by the professional. Do you feed any specific ingredients to help support your horses’ mobility? All of my horses are fed joint supporting ingredients and electrolytes. The horses performing more intense work get a supplement containing Glucosamine, Chondroitin sulphate, MSM, Hyaluronic acid and Boswellia, whereas those who are performing at the lower levels all get Glucosamine and/or MSM. I think it is important to support their joints. 28 29would be classed as providing quality protein. and as a result it is thought that they lack the ability to transport Creatine from the digestive tract (Pratt-Phillips & The need for a balanced diet that meets protein and Lysine Lawrence, 2014). requirements does not mean that specific ingredients have L-Carnitine is another ingredient often promoted as no place in supporting muscle function. Certain ingredients supporting muscle function and performance as it is can help your horse’s muscles, and therefore their mobility required for aerobic metabolism of fatty acids (Pratt- and performance. Such ingredients focus on supporting Phillips & Lawrence, 2014; Urschel & McKenzie, 2021). energy metabolism and muscle function, reducing muscle Aerobic metabolism is the predominant metabolic pathway damage, and aiding muscle recovery (Figure 3). during endurance-type exercise, therefore providing Ingredients aimed at improving energy metabolism additional Carnitine may increase aerobic capacity and within muscles are popular as fatigue is associated with a overall performance. Studies on people consuming depletion in energy substrate (mainly associated with long- Carnitine produce conflicting results with some supporting duration low intensity exercise) or accumulation of lactic its use for increasing aerobic capacity, whilst others found acid and other metabolic by-products during high intensity no influence on athletic performance (Gnoni et al., 2020). exercise. Such responses cause a decrease in muscle pH Oral supplementation of horses with Carnitine showed which negatively affects muscle contraction and key an increase in plasma Carnitine concentration, however enzymes involved in utilisation of glycogen (Pösö et al., there was no evidence that Carnitine reached the muscles 2008). Creatine is an ingredient that is often promoted as (Harris et al., 1995). The same study also showed a low able to maintain energy supply to the muscles due to its bioavailability (7%) for oral Carnitine supplementation. role in energy synthesis at the initial onset of exercise, Rivero et al. (2002) also studied the effect of oral Carnitine and its ability to buffer (neutralise) lactic acid (Pratt- supplementation to horses in training and found that Phillips & Lawrence, 2014; Urschel & McKenzie., 2021). supplemented horses showed improved muscle adaptations Creatine is found in skeletal muscle and is consumed by to training, but that such adaptations only continued humans in meat products and oral supplements. Oral whilst the horses were in training despite continued Creatine supplementation in people has been shown to feeding of Carnitine. The authors concluded that Carnitine increase muscle Creatine concentrations (Cooper et al., supplementation enhances adaptations to training but does 2012), however supplementation of horses has shown no not actually cause the changes in muscle tissue per se, significant increases on muscle Creatine concentrations therefore feeding Carnitine is only beneficial when horses or performance (Schuback et al., 2000; D’Angelis et al., are performing appropriate exercise. 2005; Teixeira et al., 2016). Creatine is poorly absorbed by equids as they have evolved consuming a vegan diet, β-Hydroxy-β-methylbutyrate (HMB) is a metabolite Stephanie Taylor International rider and breeder Stephanie Taylor is an international dressage rider and breeder competing at Grand Prix level. Steph is based in Hampshire at Webbs Green Stables where she rides and develops horses from youngsters up to fully established competition horses. 30 31(end product of metabolism) of the amino acid Leucine, associated with muscle development and recovery. Leucine, meaning it is naturally occurring in the body although in Isoleucine and Valine are all essential amino acids so must low concentrations (Szcześniak et al., 2015). In vitro and be provided in the diet. They are also classed as branched- in vivo studies have shown that HMB can stimulate muscle chain amino acids (BCAA) which are amino acids with a protein synthesis in humans and animals (Smith et al., 2005; branch off to one side of their structure. Branched-chain Szcześniak et al., 2015; Reister et al., 2017), and as a result amino acids are associated with increased performance due is fed to promote muscle development in food producing to their effect on prolonging time to fatigue and contribution animals and taken as an oral supplement by people wanting to energy sources used during exercise. Central fatigue is to maintain muscle mass. Along with Leucine, HMB when there is decreased motivation to perform exercise regulates skeletal muscle protein turnover and increases and a loss of motor coordination and is associated with lean body mass and muscle strength. Supplementation increased production of Serotonin in the brain (Farris et al., also suppresses muscle breakdown and inhibits cell death. 1998). Tryptophan is used for the synthesis of Serotonin in Ostaszewski et al. (2012) studied the effect of oral HMB the brain, therefore high Tryptophan concentrations enable supplementation on Thoroughbred horses in race training. more Serotonin synthesis. Branched-chain amino acids compete with Tryptophan for binding sites at the blood- JESSICA SEELEY'S TOP 5 TIPS FOR brain barrier, therefore a higher plasma concentration of R MAINTAINING MOBILITY E BCAA reduces uptake of Tryptophan by the brain leading PAP • Teamwork is KEY! Physiotherapist, Vet, Saddler, to a consequential reduction in Serotonin synthesis and D Farrier, Trainer, Nutritionist and anyone else E onset of central fatigue which reduces performance (Pratt- LC integral to your horse’s care should all work Phillips & Lawrence, 2014). Such an effect has been YC together (and with you!) to keep your horse in E reported in horses, with intravenous administration of R their best possible condition. % Tryptophan significantly increasing plasma Tryptophan 00 • Manage your horse’s work for their ‘use’ and 1 concentrations which were associated with a reduced N age. You don’t need to train your horse to Grand O performance capacity compared to non-supplemented Prix if their job is to enjoy hacking around the DE horses (Farris et al., 1998). Branched-chain amino acids are countryside! TNI sometimes referred to as providing an energy source for use R • Think holistically – consider their whole P during exercise however their direct contribution to energy environment including feeding, turnout and yard sources is thought to only be small (Arfuso et al., 2019). environment. They are thought however to contribute indirectly to energy • Plan your week to include physical and mental supplies and therefore prolonging exercise, through their stimulation to minimise peaks and troughs in oxidation. Oxidation of BCAA in the muscles produces work. the amino acid Alanine which can then be converted to • Look after yourself! Consider your own injuries glucose through the process of gluconeogenesis in the and potential asymmetries and the impact this could have on your horse. liver (Trottier et al., 2002). The enzymes involved in the breakdown of BCAA in skeletal muscles are found more in type 1 muscle fibres which are associated with aerobic Supplemented horses had significantly lower post- metabolism and prolonged, low intensity exercise. As such, exercise creatine kinase activity and lactate dehydrogenase BCAA supplementation, specifically Leucine, could be concentrations than the placebo group. Creatine kinase beneficial for horses performing such exercise (Trottier et and lactate dehydrogenase are enzymes produced when al., 2002; Urschel et al., 2010). muscle tissues are damaged therefore HMB was shown to be effective in reducing muscle damage. Branched-chain amino acids may also facilitate recovery after exercise, particularly exercise that depletes muscle Supplementation with certain amino acids has also been 30 31glycogen stores. Replenishing glycogen levels in equine Supplementation with BCAA is also reported to promote protein synthesis post-exercise (Jacobs et al., 2015; Hauss muscles is much slower than in other species and in humans, et al., 2021), therefore supporting muscle recovery and taking approximately 72 hours (Pratt-Phillips & Lawrence, mobility. Supplementation with antioxidants offers further 2014). Horses required to perform exercise on consecutive support for muscle recovery through their ability to days may therefore suffer from low energy levels due to reduce the production of reactive oxygen species (ROS), low muscle glycogen stores. Even when feeding meals reactive nitrogen species (RNS) and free radicals (known containing soluble CHOs (starch and sugar), glycogen collectively as oxidants) during exercise and scavenge replenishment in muscles is slow. One proposed reason for any oxidants that are produced (Lykkesfeldt & Svendsen, this is that equids do not show the increased sensitivity to 2007). Oxidants damage cell membranes and structures insulin after exercise that is seen in humans and other species and therefore affect cell function (Kirschvink et al., 2008). (Pratt et al., 2007). Insulin is needed to promote storage of Vitamin E, MSM, Coenzyme Q10 and various herbs are all glucose as glycogen, therefore this lack of response likely promoted to have potent antioxidant properties (Williams, contributes to the slow muscle glycogen replenishment. 2008; Sinatra et al., 2013; Tanvir et al., 2017; Butawan et Urschel et al. (2010) found that administering Leucine to al., 2020) although further research is needed to support resting and exercising horses increased plasma Leucine some of these ingredients. concentrations in all horses. Leucine is known to stimulate The final ingredients to highlight for supporting your insulin secretion in horses, which was evident in the study horse’s muscles are electrolytes which may not always be by Urschel et al. (2010) as plasma insulin and glucose thought of for muscle function. However, they are integral concentrations were significantly raised post Leucine for normal muscle and nerve function and therefore should supplementation. This response to Leucine is a potential be replenished in horses that produce any considerable method of stimulating glycogen storage in horses without amount of sweat, regardless of their workload. For those having to feed a high starch or sugar meal. Etz et al. (2011) performing work at lower levels, regular table salt (sodium also reported an increase in plasma Leucine concentration chloride) can be fed daily at a rate of 3-10g per 100kg of in response to consuming Leucine, however they did not body weight, as sodium and chloride are the two main report any effect of supplementation on insulin and glucose electrolytes lost in sweat (Marlin & Nankervis, 2002). For plasma levels. The same authors also reported considerable those producing greater amounts of sweat an electrolyte variation in results between horses, suggesting that some product is likely to be more applicable. horses could benefit from supplementation whilst others will not. It must also be highlighted that Casini et al. (2000) SUMMARY and Stefanon et al. (2000) did not report any significant Supporting your horse’s mobility is a holistic combination effects of administering BCAA to exercising horses. of correct management, training and diet supported by Do YOU have anything you would like our Scientists to research? If you have any specific topics that you would like us to feature in The JEN, please email us at: [email protected] 32 33therapeutic and veterinary treatments when required. Only knowledge to support your horse’s health and performance focusing on one of these elements will likely limit any but will also have the appropriate insurance should it be benefits on mobility. The benefits of physiotherapy are required. The review of ingredients to support mobility highlighted although you may find an alternative therapy is is not exhaustive but provides an overview of the more more suited to your horse’s specific requirements. What is common ingredients fed. The use of such ingredients important is that you use qualified, certified professionals should be in the context of a balanced diet that is specific to to undertake such treatments, as they not only have the your horse’s requirements. REFERENCES Agar, C., Gemmill, R., Hollands, T., & Freeman, S.L. (2016). The use of nutritional supplements in dressage and eventing horses. Veterinary Record Open, 3: e000154. Ainsworth, D.M. (2008). Lower airway function: responses to exercise and training. In: Hinchcliff, K.W., Geor, R.J., & Kaneps, A.J. (eds) Equine Exercise Physiology. Saunders Elsevier, London, UK. Arfuso, F., Assenza, A., Fazio, F., Rizzo, M., Giannetto, C., Piccione, G. (2019). 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Published on the internet: [Accessed 8 August 2021]. 34 35Nutrition of the weanling foal: from weaning to twelve months Abigail Malone, BSc In the last issue of the JEN, we covered broodmare nutrition time for both mare and foal as ultimately the mare and foal so now we will review the nutritional requirements of are separated, and the foal mixed with a group of young growing foals. For the first six months or so of the foal’s horses (Figure 1). Creep-feeding your weanling is a good life its diet predominantly consists of the mare’s milk, with idea to gradually introduce them to hard feed if the dam small amounts of grass, forage and concentrate feeds also has not been receiving any, as this will help to reduce stress being consumed. As the foal nears the time to be weaned at weaning time and ensure they begin receiving a from its dam the proportion of milk in the diet reduces balanced ration. whilst the amount of other foods increase, meaning there As most weaning takes place when the foal is six months needs to be consideration of what feedstuff to offer and old, we will explore the foal’s nutritional requirements R how best to allow the foal to develop into a strong yearling, EP starting from six months of age. A balanced, nutritional A regardless of what their future lifestyle maybe. A weanling P ration is extremely important for the weanling as they are at DEL a vital stage of growth, and how well they are able to grow CY at this stage will influence their future athletic potential, CER with insufficient nutrients having the potential to cause %00 health problems later in life (Staniar, 2013). A weanling 1 N will eat less than a yearling in volume, but still requires O D certain nutrients so a nutrient concentrated diet is ideal. ETNI ENERGY RP The energy requirements of the weanling are partitioned Figure 1. Weaning can be a stressful time for both foal and mare. Where into energy for maintenance (normal body functions possible wean foals in pairs or small groups to allow them to develop bonds with others which helps to reduce stress. and activity) and energy for growth (Frape, 2010). As growth rate is greatest at this age the weanling requires is a horse that no longer relies and suckles on their mother’s considerable energy for its body size, evident by comparing milk. Weaning usually occurs when the foal is between four the daily 70Mj of digestible energy (DE) required by and six months old, although when the foal is weaned will a 500kg horse at maintenance, to the 65Mj DE required depend on a number of factors which could be related to by a 6-month-old weanling weighing an estimated 216kg the foal or its dam. If the foal is growing too fast, gaining (NRC, 2007). As shown in Table 1, the DE requirements too much body fat, showing any signs of developmental of the foal increase as it gets older due to the increase in orthopaedic diseases (DOD) or other conformation defects, body mass. The estimated daily weight gain at six months then weaning may take place sooner so the nutrients the old is 0.72kg per day, at nine months it is 0.57kg per day foal receives can be controlled (Becvarova & Buechner- and 0.45kg per day at twelve months old (NRC, 2007). Maxwell, 2012). Weaning may also take place early if the This shows that although growth rate slows down over the dam is unable to supply enough quality milk or if she is months, the weanling still requires increased energy for losing condition. Weaning can be an incredibly stressful 34 35maintenance and development due to their increased body weanling, however this may decrease over time as they size. As youngsters mature and development slows down, acclimatise to the low temperatures (Autio et al., 2008). the amount of energy required for development reduces, Whilst some breeds are considered easy keepers, such as aligning their overall energy requirement to that of adult drafts and native pony types, others such as Thoroughbreds horses once they mature. are classed as hard keepers and therefore can have slightly higher energy requirements which should be factored into The weanling’s energy requirements will also vary their feeding rations (Ralston, 2021). Whilst the foal is depending on their date of birth, climate, condition and still suckling, the mare’s milk will provide almost all of individual metabolism (Staniar, 2013). Foals born in early the required energy, and as the foal gets older forage will spring tend to have a heavier birth weight than those born become an increasing part of their diet and concentrate feed later in the foaling season. As all foals tend to be weaned may also be introduced to the weanling. Weanlings who at similar times, those born earlier are older at weaning are energy deficient will have a reduced growth rate and and so generally have greater energy requirements. reduce their chances of reaching their potential. However, Colder conditions will increase the energy demand of the Table 1. Daily nutrient requirements for the weanling at six, nine and 12 months old with a predicted mature weight of 500kg. 6 months 9 months 12 months % change from 6 months NRC requirements (~216kg) (~275kg) (~321kg) old to 12 months old Digestible energy (Mj) 67 74 79 18% Crude protein (g) 676 758 846 20% Amino Acids Lysine (g) 29 33 36 19% Macro Minerals Calcium (g) 39 38 38 -3% Phosphorus (g) 21 21 21 0% Sodium (g) 5 6.1 6.9 28% Chloride (g) 20.1 23.3 26.5 24% Potassium (g) 13 15.4 17.4 25% Magnesium (g) 4.14 4.83 5.39 23% Sulphur (g) 6.5 8.2 9.6 32% Trace Elements Cobalt (mg) 0.2 0.3 0.3 33% Copper (mg) 54 68.7 80.3 33% Iodine (mg) 1.5 1.9 2.2 32% Iron (mg) 215.9 274.6 321.2 33% Manganese (mg) 172.7 219.7 257 33% Zinc (mg) 172.7 219.7 257 33% Selenium (mg) 0.43 0.55 0.64 33% Vitamins Vitamin A (IU) 9715 12358 14455 33% Vitamin D (IU) 4318 5492 6424 33% Vitamin E (IU) 432 549 642 33% B1 - Thiamine (mg) 16.2 20.6 21.4 24% B2 - Riboflavin (mg) 10.8 13.7 16.1 33% Calculations based on NRC (2007) recommendations 36 37many weanlings are able to compensate after a short period being 676g compared to 630g per day, respectively. These of restricted energy supply, during the winter months for requirements highlight the need for quality forage and feed example, which should not affect their growth long term to be provided at this vital growth phase. Supplemental (Saastamoinen, 1996). Whilst meeting requirements feed should contain at least 16% crude protein with 0.7% is key, care should be taken not to excessively exceed Lysine (Becvarova & Buechner-Maxwell, 2012). In one the weanling’s energy requirement as this may increase study, 12 weanling foals were given 70, 100 or 130% of excitability and the risk of the foal developing DOD and their energy and protein requirements as indicated by the other skeletal abnormalities due to periods of rapid growth National Research Council. Even though they were also (Thompson et al., 1988). Overfeeding and thus providing provided with 100% of their Calcium and Phosphorus the weanling with too much energy will induce rapid requirements, both over and underfeeding of energy and growth and puts excessive stress on the joints causing them protein negatively affected their growth plate cartilage, to grow abnormally (Frape, 2010). These abnormalities can which could influence their future development and ability be seen from feeding as little as a third more energy than to undertake an active lifestyle (NRC, 1978). the weanling requires (Becvarova & Buechner-Maxwell, VITAMINS AND MINERALS 2012), however once the correct energy supply is provided From six to twelve months old most of the weanling’s R you must then consider other nutrient needs to continue EP macro mineral, trace element and vitamin requirements A supporting optimum growth. P increase between 23% and 33% (Table 1), with the DEL PROTEIN exception of Calcium which stays relatively the same and CY Amino acids are the building blocks of protein and are Phosphorus which does not change at all (NRC, 2007). CER classed as essential amino acids that must be obtained from Minerals are vital as they ensure growth and development %0 the horse’s diet, and non-essential amino acids that the of skeletal and muscle structures. Calcium and Phosphorus 01 N horse is able to create internally (Frape, 2010). Protein is are considered together and are both incredibly important O required to form structural molecules such as collagen and for the weanling as they are used for bone development DET can also be found in cell membranes, enzymes, antibodies, and muscle function. A deficiency of either or both of NIR and hormones, making them vital for the body to function, these minerals (or an imbalance in the ratio of Calcium P grow and repair. The only essential amino acid for which a to Phosphorus which should be 2:1) can negatively affect daily requirement has been calculated for horses is Lysine, bone and cartilage formation (Frape, 2010, Stainar, 2013). and we can see from Table 1 that the crude protein (CP) and A high grain diet may be high in Phosphorus and lead to Lysine requirements increase as the weanling grows. Lysine a negative imbalance and induce a Calcium deficiency is also the first limiting amino acid which means even if (Hintz, 1996), whereas weanlings on a forage-only diet may the horse is receiving more CP in their diet than needed, be deficient in Phosphorus (Stainar, 2013). It has also been they can still be deficient in protein if insufficient Lysine shown that a diet deficient in Copper can lead to skeletal is provided. This is particularly key for the weanling as it problems due to poor collagen quality, osteochondrosis may hinder their growth and development (Saastamoinen, lesions and weakened cartilage (Hintz, 1996). In order to 1996). Exceeding protein requirements is unlikely to have maintain Copper metabolism, Zinc must be supplied in any detrimental effect, yet limiting it can result in reduced the appropriate ratio of 1 part Copper to 3.2 parts Zinc, body weight, height, and cannon bone circumference in otherwise it may inhibit absorption (Hintz,1996; Staniar, weanlings under twelve months old (Savage et al., 1993). 2013). Manganese is used for the formation of Chondroitin Like DE, the CP requirements for a six-month-old weanling sulphate, which is integral for healthy cartilage, and so are greater than those of a 500kg adult horse at maintenance, must not be overlooked for the vital growth phase of 36 37the weanling (Stainar, 2013). SUMMARY Growth is not only affected by the diet but also by Vitamins must also be considered key to the diet. Fresh genetics and the weanling’s environment. Body weight forage is high in Vitamin A and deficiencies are rare however alone is not an ideal indicator of the effect of nutrition on cut forage will begin to lose its vitamin content over time the weanling, whereas analysing wither height and other (Stainar, 2013). Over supplementation of Vitamin A can skeletal developments are likely to be more useful (Staniar, have negative effects such as hyperextension of various 2013). Body condition scoring has a place to ensure joints and ataxia (lack of muscle control and coordinated youngsters do not become overweight, however, it should movement), whilst a deficiency will hinder immune and not be used in isolation due to this being a rapid growth reproductive function (Stainar, 2013). A weanling is only phase and short-term fluctuations in growth to be expected. probably prone to a Vitamin D deficiency if they do not have access to fresh forage and are kept inside out of daylight Good quality forage (hay/haylage and grazing) along with which is not the case for most foals. A Vitamin D deficiency a youngstock feed or the addition of a vitamin and mineral can however decrease the quality of skeletal development supplement containing quality protein, should be more than (Stainar, 2013). Vitamin E is required for immune function adequate to keep your weanling in good condition and set and deficiency may result in the degenerative condition them up for their future careers. Weanlings on spring and Equine Degenerative Myeloencephalopathy (EDM), summer grazing will need far less supplementary feed for although this is only likely if the horse does not have calories than those consuming hay or haylage in the autumn access to pasture. and winter periods, but care must be taken to ensure they are still receiving their vitamins and minerals. Sending off A high forage diet is required for normal gastrointestinal forage and pasture for analysis will allow you to determine tract function and health as well as to support the natural what nutrients your weanling will need to be supplemented behaviours of the weanling. Providing a forage-only with. Both under and over feeding can negatively affect diet, if good quality, will likely meet the weanling’s bone development and neurological function (Becvarova energy and protein requirements. 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Protein, amino acids and energy requirements of weanling foals and yearlings. Pferdeheilkunde, 12(3): 297-302. Thompson, K.N., Jackson, S.G., & Rooney, J.R. (1988). The effect of above average weight gains on the incidence of radiographic bone aberrations and epiphysitis in growing horses. Equine Veterinary Science, 8: 383-385. 38 39Glossary Acid buffer Reduces the acidity of the horse’s stomach acid. Acid detergent fibre A combination of cellulose and lignin. Anti-inflammatory A substance that reduces or treats inflammation and/or swelling. An organism that uses food supplied in the internal or external environment of the Commensal host animal. Creep-feeding A feed, normally pelleted, given to nursing foals that the broodmare cannot access. Crude protein Calculated by the nitrogen content of foodstuffs. Developmental Orthopaedic A number of conditions that occur in growing horses such as osteochondrosis, limb Diseases (DOD) deformities and physeal dysplasia. Digestibility The amount of nutrients actually absorbed by the horse. Digestible energy Amount of energy in the feed minus the amount of energy lost in the faeces. Distension A term used for a gastrointestinal disorder that causes expansion and discomfort. The part of a foodstuff that remains after all water has been removed. Foods are Dry matter R compared on a dry matter basis as nutrients are only contained in the dry matter. EPA Faecal output The amount of faeces that is passed. P D From the mouth to the anus including all of the digestive organs. Where food is E Gastrointestinal tract L ingested, nutrients are absorbed and faeces are expelled. CYC A messenger that acts on cells and/or blood vessels to promote an inflammatory E Inflammatory mediator R response. %0 In situ In the original place, e.g. in the animal 01 N Biological processes that occur outside of the body, but within laboratory equipment In vitro O such as a test tube or culture dish. DET Biological processes that occur inside a whole living organism, e.g. an animal or In vivo NI person. RP Ingest To take food or drink into the body by swallowing or absorbing. Metabolites A substance formed by, or necessary for, metabolism. Specific microorganisms (bacteria, protozoa, fungi) living in a specific environment, Microbiota e.g. the equine gastrointestinal tract. Nasogastric Reaching or supplying the stomach via a tube. Measures most of the structural components of plant cells, commonly used in animal Neutral detergent fibre feed analysis. Orts Uneaten food left after a meal. Pathogen A microorganism such as bacteria or a virus that can cause disease. Promotes growth and activity of beneficial intestinal microorganisms such as bacteria Prebiotic and fungi. Probiotic Live microorganism that promotes restoration of gut flora. Pro-inflammatory A substance capable of causing and/or promoting inflammation. A fatty acid with less than six carbon atoms, obtained from indigestible foods via Short chain fatty acids intestinal microbial fermentation. Volatile fatty acids A group of fatty acids produced in the horse’s hindgut by cellulose digesting microbes. 38 3942 YEARS AT THE CENTRE OF EQUINE NUTRITION 40 PB