Equitalk. In conjunction with Dr Rachel Neville, Senior Lecturer, Lincoln University. Keeping up to date with the latest research in equine nutrition

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1 Equitalk Keeping up to date with the latest research in equine nutrition In conjunction with Dr Rachel Neville, Senior Lecturer, Lincoln University Free radicals and chronic laminitics Dr Rachel Neville from The University of Lincoln is leading studies to investigate the relationship between free radicals and a very specific group of ponies, those that have suffered from laminitis. Dr Neville explains some of the theories behind her research. Chronic laminitics have three times the amount of free radical damage compared to non laminitic ponies What are Free Radicals? Free radicals are highly reactive particles (atoms or molecules) found in cells and tissues. They are produced naturally in the body whenever oxygen is being used. Energy production at cell level uses oxygen and free radicals are produced as a by-product. Free radicals are unstable and will grab a piece (electron) from another atom. This stabilises the free radical, but damages the atom it attacked and the cell or tissue that the atom is found in. Are Free Radicals good or bad? Free radicals damage cells and tissues so are bad. But they do have beneficial effects in the body too; white blood cells use them to kill invading bacteria and disease organisms. Some free radicals are necessary and a normal part of metabolism; however excessive production is bad. What causes excessive production of free radicals? Illness will increase free radical production due to the increase in white blood cells to fight the infection as will unaccustomed exercise and aging. How does the body protect itself from free radical damage? If the body can give the free radical its missing bit so that the free radical becomes stable, the free radical can no longer cause damage. The substances which can donate the missing bit are called anti-oxidants and they can be produced within the body or provided by the diet. Why look for free radicals in laminitics? The original work on anti-oxidant status in horses and ponies was carried out as part of my PhD studies. This research looked at the relationship between free radicals and aging, by collecting urine samples from which free radical damage was measured. All the horses used had been diagnosed as being clinically healthy for the last 12months. However within the huge group of urine samples, 3-4 horses had extremely high values of free radical damage. On re-contacting the owners it was found that these horses had suffered from laminitis but had not had the disease for 24months. We carried out further work in conjunction with Dodson & Horrell Ltd. Our research was published in a paper which reported the finding that Chronic laminitics have three times the amount of free radical damage compared to non laminitic ponies. (Neville. R, Hollands.T, Keyte.F, (2004) Evaluation of urinary TBARS in normal and chronic laminitic ponies EVJ 36, (3); Neville. R (2005) Proceedings of the Dodson & Horrell Fifth International Conference on Feeding Horses) Dietary Support for horses and ponies with Chronic Laminitis Some horses and ponies can suffer from chronic laminitis for most of their lives, but they might not be lame. In order to minimise their risk of laminitis they are often kept on restricted grazing. Grass is one of the main sources of anti-oxidants for our horses, so if grass is being restricted it is important to provide this group with dietary sources of anti-oxidants in order to combat these high levels of free radicals. Remember though that anti-oxidants are not a cure for laminitis. Dodson & Horrell have a number of products which are suitable for horses and ponies to laminitis including Safe & Sound which was formulated based on Dr Neville s research. EDITION O1 2006

2 Dr Teresa Hollands BSc (Hons) MSc (nutrition) PhD R.Nutr, Senior Nutritionist at Dodson & Horrell explores some of the recent research into factors related to laminitis and considers how the results can be utilised. Laminitis is described as a multifactorial disease; in other words there are so many factors which might have an impact on why a horse gets laminitis that a straightforward solution to preventing the disease simply does not exist. In the same way that many pieces have to be put together to solve a complicated jigsaw, so researchers from around the world discover links, that one day when they are all put together may explain the aetiology of the disease. However the picture is getting clearer and recent research provides some of the keys to a successful management and preventative programme Key 1 Weight control and prevention of obesity: - The research into the relationship between equine metabolic syndrome, laminitis and weight control has been initiated by Professor Philip Johnson from The University of Missouri What is Equine Metabolic Syndrome? 1. it is a bit like type 2 diabetes in humans 2. it is a group of symptoms not one specific disease 3. symptoms include obesity, insulin resistance, laminitis, stress 4. typically found in horses and ponies with a genetic predisposition to putting on weight, usually native types 5. there is a human version of the syndrome Equine metabolic syndrome, (EMS) is very similar to human metabolic syndrome, (HMS) and most instances of HMS are attributable to the combined effects of inappropriate dietary intake, insufficient physical activity, and the development of obesity in genetically susceptible individuals (Professor Philip Johnson, Dodson & Horrell Fifth International Conference on Feeding Horses) The link between obesity and the development of EMS is a long term one and it is likely to become a problem if it PERSISTS! As Prof Johnson explains the horse in evolutionary terms lays down fat to Get ready for an anticipated (planned) period of TEMPORARY environmental harshness and this happens every winter. There is an activation of survival mechanisms including insulin resistance and enhanced inflammatory reactivity. These mechanisms happen even though the horse is still being fed excess calories. The consequence of long term obesity, (condition score over 3 out of 5, cannot feels ribs) is severe. New research has shown that not all fat is the same. Researchers in both human and equine science used to think that adipose tissue (fat stored under the skin in adipocytes) was simply a depot of excess energy. However we now know that specific areas of fat cells act very differently. Fat tissue can act as an endocrine organ (gland) i.e. it Hormones, (adipocytokines) secreted by omental 1 fat in humans and possibly crest in equines 1. Resistin 2. Leptin 3. Adiponectin 4. Interleukin-6 5. TNFa (Tumour-necrosis factor alpha) 6. Mineralocorticoid releasing factor 7. Free fatty acids 8. Cortisol 1 fat stored around the stomach cavity secretes multiple hormones (adipokines). Professor Johnson notes that hormones produced by fat cause the fat tissue to be maintained and perpetuate itself, in fact it could be considered craving fat tissue and regarded as a benign growth that is difficult to budge!! Craving fat is stored around the stomach in people and might be stored in the crest of horses. Why worry about omental or craving fat? Adipokines tend to interfere with the action of many systems including immune function, glucose homeostasis, inflammation, and vascular biology (blood flow). They have a major effect on insulin activity which may cause insulin resistance so that, insufficient glucose is delivered to target cells and too much glucose is delivered to cells that do not depend on insulin (endothelial cells). (NB Chris Pollitt s theory of laminar failure is that the attachment fails because the lamella cells are starved of glucose). The seriousness of too much of the 'wrong fat' has far reaching effects on both the human and equine body, most notably changes in blood flow which can result in heart attacks in people and laminitis in horses. Case history report Professor Johnson, College of Veterinary Medicine, University of Missouri Client s observations 12-year-old Morgan mare Body condition score >3.5 (cresty neck) Attempts to breed have been unsuccessful Tendency to be lame due to sore feet Readily develops laminitis when turned out to pasture Laminitis is worsened by inactivity Tests taken by Professor Johnson Fasting plasma glucose concentration [slightly elevated] Fasting serum insulin concentration [elevated] Urinary cortisol/creatinine ratio [normal] Serum e-acth concentration [normal] IV glucose tolerance test [delayed] Dexamethasone suppression test [WNL Points of Note Glucose reference range: mmol/l Insulin reference range: <300 pmol/l Ideal ratio (glucose/insulin): > 4.5 NB. Do not use this example as self diagnosis, all clinical exams must be done by a qualified vet; do not be misled by unqualified experts.

3 Check if you are at risk of HMS 1). Measure your waist so that the tape measure passes over your tummy button, do not pull the tape tight. Note the number. 2). Measure your hips by passing the tape-measure around the widest part of your bottom, note the number. 3). Divide your waist measurement by your hip measurement. It should be below 0.8 for women and 0.9 for men if it is more, even if you are not fat you are at risk of having craving fat with the subsequent consequences. As yet there is not a simple measure to do for horses but if he is condition score 3.5 or more and you cannot feel his ribs, then he is AT RISK. Key 2 Calorie control from forage Hay Research by a plant agronomist, Kathryn Watts in conjunction with Rutgers University, USA presented at a conference in Arizona highlighted that it is important to consider the forage part of the diet when considering both calorie control and the intake of starch and sugar. Horses were fed soaked and unsoaked hay and the amount of glucose appearing in their bloodstream 1hr and 1.5hrs after eating was measured. The reduction in sugar content of the soaked hay significantly reduced the plasma glucose peak compared to the unsoaked hay. More importantly the insulin response to soaked hay was higher than unsoaked hay. Thus if you are looking to reduce the insulin response to a forage, it is best to feed soaked hay. Table 1 - Effect of different soak times on the sugar content of hay Nutrient 0 mins 30 mins 60 mins Starch%* Sugar %* DE MJ/kg* UK (D%H lab) * Cottrell, Watt and Ralston, (2005) Proceedings of Equine Science Soc, Tucson, USA ** Hollands and Sainsbury, (2006) D&H laboratory Table 3 - Non structural carbohydrate, (NSC % dry matter) content of common herbs, weeds and dead grass found in horse paddocks* Grass (sample month) Starch Sugar Fescue (Jan) Brome (Jan) Orchard grass (Jan) Tall fescue (Jan) Perennial ryegrass (Jan) Herb/weed Dandelion Red clover White clover Wild oats * Watts, (2005) Proceedings of Equine Science Society Tucson USA The concentrations of fructans in grass are at their highest at the typical laminitis times of the year as illustrated in the graph below, (Vervuert et al, 2005 Proceedings of The Equine Science Soc, Tucson, USA) Variation in frutan content of grass throughout the year 60 Grass Work in both the USA, (Watts et al, 2005) and Germany, (Vervuert et al, 2005) has established the amount and variation in soluble sugars and fructans found in pasture grasses. The pastures analysed in the USA contained timothy, blue grass, tall fescues, and orchard grasses and the levels of sugar are shown. fructans g/kgdm Table 2 - Variation in sugar content in USA grasses 10 % soluble sugars* am pm After overnight@ 16º After frost May June July August September October November * Allen et al, (2005) Whilst the ability of the horse to consume enough fructans to trigger laminitis remains controversial, it is worth noting that horses on bare paddocks which are not managed properly and allowed to go to weed might be consuming reasonably large amounts of sugar. Indeed dead grass in winter paddocks might need monitoring as shown in table 3. Dr Ingrid Vervuert also found fructans levels in hay varied between 5 and 37g/kgDM, whereas haylages contained less, between 3 and 19g/kgDM A separate study also carried out in Germany, (Grabler and Uwe von Borstel, 2005, Third European Nutrition Conference, Hannover) found that Perennial Ryegrass contained more fructans ( g/kgDM) than any other pasture grass, (22-43g/kgDM). Their study confirmed the results of Ingrid s that the highest fructan content is found in the first growth in May and the last growth in October.

4 Key 3 Inflammation control:- Over the last century, researchers have been discouraged from using the word laminitis because it meant inflammation of the laminae and in the early 90s it was recommended that the disease should be re-named lamellar degradation. However in the last few years Professor Jim Belknap and his team from Ohio State University have questioned this dogma for 2 main reasons. 1. that the most successful drug treatment for laminitis are the non steroidal anti-inflammatory drugs, (NSAIDs e.g. Bute) 2. horses or ponies suffering from laminitis share similar clinical signs to humans suffering systemic inflammatory response syndrome (sepsis) Professor Belknap presented some fascinating findings at BEVA 2005 where his initial investigations look like they are confirming that laminitis does in fact share similar biochemical and molecular pathways to human sepsis and that there is inflammation in many of the horse s tissues/organs; it s just more catastrophic in the foot. His group were looking at what genes were being expressed in the lamella tissues of horses suffering from laminitis and found that the ones which were most increased were those at the centre of the inflammatory process. Professor Belknap noted that the peak expression of lamellar inflammatory gene expression occurs before there is heat, digital pulse or lameness. The group have also found huge influxes of white blood cells into the lamellar tissue during the developmental stage of the disease. In fact they are claiming that the changes which take place in the sensitive lamellae during the developmental and acute stages of laminitis cause damage to the tissue in the same way that organ failure occurs in human sepsis. In human sepsis, there is usually multiple organ failure rather than the single organ failure of the lamellae in the horse. Therefore the researchers took skin samples from laminitic horses to see if there was the same huge influx of white blood cells in the dermal cells of the skin compared to the dermal cells of the lamellae and there are!!!!!! So why does the foot fail and not the skin? It appears that the tissues of the foot do not have the same ability as those in the skin to mop up reactive oxygen species or (free radicals associated with inflammation) and thus the cell damage is far more acute and even life threatening. At the present moment in time the research is not far enough advanced to translate it into what we can do as horse owners. However Professor Belknap concluded his presentation by saying these new data are exciting to those of us frustrated by a general lack of progress in the clinical situation, in that we may now be able to take note of the incredible amount of research, including some of the recent successes in clinical trials, for the management of human sepsis and organ failure related to sepsis. This research might explain why Neville & Hollands found higher levels of free radical damage in chronic laminitics compared to normal ponies. The following provides advice on the management and feeding for weight control and calorie counting: - Key 1 Weight control Ensure that your horse does not become fat and provide regular exercise Horses which have a condition score>3 for a long period of time are likely to be at a greater risk of insulin resistance. Use your condition score card, feeling for fat not muscle weekly or fortnightly and record your horse s condition. Know what the average weight is for your type of horse and try and maintain him within the range. Weigh your horse fortnightly with an accurate weightape,(ellis and Hollands, 1998;2000) and record his weight. Reduce energy, (but not bulk) intake if the weightape shows weight increasing. If your horse is gaining weight then reduce the amount of calories that he is eating, but not the bulk. Exercise has been shown in humans to have a protective effect on insulin resistance. Make sure your horse is exercised daily unless he is lame from laminitis; confer with your vet and farrier as to when you can start exercising your horse. Increase exercise to aid in weight loss and weight loss maintenance, consider turnout with a muzzle. Weightapes and condition score cards are available from Dodson & Horrell, please contact our Helpline for further details.

5 Key 2 Counting calories: - the working horse Ensure that excess storage carbohydrate does not reach the hind gut Use a concentrate feed containing micronised cereals, (cooked starch) which maximises starch digestion in the small intestine, (Mclean et al, 2000). Dodson & Horrell have adjusted their micronising process based on the research carried out at Edinburgh University to increase the digestion of starch in the small intestine. Do not exceed a maximum of 2 g starch/ kg BW/meal. Pasture Mix contains 250g starch/kg, so in theory you can feed 4kg per meal to a 500kg horse before overloading the small intestine s capacity to digest starch; assuming that the horse is in hard work and not putting on weight. Feed small meals so that stomach capacity is not overloaded. Do not feed more than 2.5kg of concentrates in one meal to a 500kg horse or 1.75kg to a 350kg pony (i.e. a maximum 0.5 kg concentrate/ 100 kg BW/meal) However, whenever possible feed less than the above per meal and increase the number of times you give a meal per day rather than increase the size of the meal. Key 2 Counting calories: - the leisure horse Maintain bulk intake but reduce calories Horses and ponies must not be starved, they need to eat at least 1.5% of their bodyweight in food dry matter, preferably 2-2.5% Substitute hay soaked for 12hrs to reduce energy content or use oat straw instead of hay if you are restricting grass intake Feed extra levels of anti-oxidants to protect against the free radicals. Safe and Sound has increased levels of anti-oxidants Plentiful supplies of antioxidants are found in grass, but restricted grazing and/or hay diet means that intakes will be reduced considerably. Weigh feeds and forage. Summary of the lessons to be learnt from the research The new research is aiding us to understand how and why laminitis occurs, but the basic management advice still remains the same What is absolutely clear is that obesity is linked to an increase risk of laminitis, regardless of the diet fed to the horse or pony IT IS ESSENTIAL that the body condition of your horse remains below 3 You MUST be able to feel their ribs Horses or ponies whose ribs cannot be seen or felt are at risk at developing a problem with their glucose and insulin response due to possibly hormonal or genetical influences Ensure adequate anti oxidants to minimise the destructive effects of free radicals Make sure adequate good quality protein is fed to ensure formation of good quality hoof wall Control the intake of water soluble carbohydrates to less than 10% in the forage, Remember to consider fructan intakes. New research suggests that these are fermented by bacteria in the small intestine not the bacteria in the hind gut. This might explain why small quantities of fructans might affect horses. Current nutritional opinion is that there is not enough fructans in grass to trigger the effect in the hind gut that was shown experimentally. The horses simply cannot eat enough quickly enough..however there are always exceptions!! Prevention is better than cure Seek advice.

6 Dodson & Horrell have a number of products which are suitable for horses and ponies at risk from laminitis including Leisure Mix, Pasture Nuts, Fibergy, Stand Free, Surefoot and Safe & Sound. Dodson & Horrell are committed to the continuing research into the causes of laminitis and the provision of information for the horse owner. The research carried out by Dodson & Horrell in conjunction with Dr Neville has helped us to continue to improve the suitability of products as well as playing a vital part in the formulation of new products such as Safe & Sound. Safe & Sound Low energy Fully balanced Added herbs for hoof and coat condition Nutri-nut to maximise chewing and increase eating time Yea-Sacc to encourage beneficial bacteria in the hind gut Low starch Low fructans MSM for its soothing properties Biotin to help maintain hoof integrity QLC a natural source of anti-oxidants Nutritional Helpline on (normal national rates apply) Dodson & Horrell Ltd Kettering Road, Islip, Kettering, Northants, NN14 3JW Tel: +44 (0) Fax: +44 (0) enquiries@dodsonandhorrell.com