The science behind SPILLERS

Two recent weight loss studies have both shown that belly girth measurements* are more closely related to changes in bodyweight in early weight loss (after the first week of feed restriction) as opposed to the more commonly used heart girth measurements or even some ultrasound fat measurements.

A study examining Managed weight loss in obese ponies: evaluating weight change, health and welfare¹, conducted last year by researchers at the Department of Veterinary Clinical Science at the University of Liverpool and supported by World Horse Welfare, suggested that it would be beneficial to find a more accurate method for monitoring early weight loss in overweight ponies rather than relying on conventional equine body condition scoring.

A further study comparing two practical weight loss protocols for the management of overweight and obese horses and ponies² was conducted earlier this year by the Department of Veterinary Clinical Science at the University of Liverpool and funded by the government-initiated Knowledge Transfer Partnership and the WALTHAM Equine Studies Group. It confirmed that the proportional change in belly girth was more closely associated with changes in body weight than the proportional change in heart girth in the early stages of weight loss.

Dr Caroline Argo and Alex Dugdale of the Department of Veterinary Clinical Science at the University of Liverpool said: "It is important for owners to understand that early weight loss is not immediately recognisable as a change in the horse or pony’s overall appearance or body condition score. However, owners do need some assurance that measures taken to promote weight loss are being effective. Simply measuring belly girth at regular (weekly) intervals can provide this. Without such reassurance, we might be inclined to either give up or more alarmingly, harmfully increase our efforts to induce weight loss."

Clare Barfoot BSc (Hons) RNutr, the research and development manager for SPILLERS and a member of the research team for the second study continued: "Our findings clearly support the concerns raised in the initial study on the accuracy of using conventional body condition scoring or heart girth measurements to monitor early weight loss. Although weigh tapes used around the heart girth can estimate bodyweight they are not as reliable in picking up early weight changes in weight loss programmes. Measurements around the belly girth have proved to be a more reliable way to monitor weight loss although it is important to ensure that the initial measurement is taken a week after food restriction to accommodate initial losses in gut fill and water, and that measurements are taken in a standard way at a similar time of day."

Samantha Lewis, Right Weight Manager for World Horse Welfare, commented: "This research will be of great benefit to owners who are taking steps to help their horses lose weight by enabling them pick up on changes at an earlier stage. While weightapes used at the heart girth can be useful to obtain estimates of body weight, changes in belly girth may be more sensitive for monitoring early changes in weight when obese ponies are encouraged to lose weight."

The researchers are still working on validating a more accurate body condition scoring system, based on the findings. In time they hope to be able to create a more effective weight loss assessment method for owners to use.

* Taken at the widest point of the belly; approximately two thirds of the way between the point of the shoulder and the point of the hip.

¹Dugdale A, Curtis G, Argo, C McG: Department of Clinical Science, University of Liverpool, UK
Harris , P A: Equine Studies Group WALTHAM Centre for Pet Nutrition, UK

²Curtis CG, Dugdale AHA, Grove-White D and Argo C.McG. University of Liverpool, UK
Harris PA. Equine Studies Group WALTHAM Centre for Pet Nutrition, UK
Barfoot CF. Mars Horsecare UK Ltd

New research¹, presented at the Equine Science Society Symposium in Nashshville, USA last month, shows that using a grazing muzzle can reduce the pasture intake of ponies by over 80%.

Horses, and especially ponies, given free access to grass appear to be more susceptible to obesity and related disorders, such as insulin resistance and laminitis, than those with restricted access to grass. However, even reducing time at pasture may not be as effective as previously thought. Another study, also presented at the meeting, has shown that ponies may adapt their grazing behaviour to eat more in a short time span². The new research shows that the use of a grazing muzzle could be a much more effective and reliable solution if used appropriately.

Grazing muzzles significantly reduce bite size and intake. Anecdotally, ponies fitted with grazing muzzles spend a greater proportion of time engaging in foraging and eating directed behaviours than their non-muzzled counterparts, yet either lose weight or retain an established, trim body condition.

The study, which was conducted by the WALTHAM® Equine Studies Group in collaboration with Dr Annette Longland of Equine Livestock and Nutrition Services in Wales, aimed to quantify the effect of wearing a grazing muzzle on herbage intake by ponies.

Four mature ponies were recruited for the study. After an adaptation period, their pasture intakes were determined when wearing a grazing muzzle and when grazing without a muzzle. Pasture samples were obtained daily to assess the grazing available. Insensible weight loss (ISWL) was determined for each pony immediately preceding and immediately following each three hour grazing period. Intakes were determined by changes in body weight (after taking into account the weight of any faeces and urine produced plus the estimated ISWL) after the three hours of grazing, using a calibrated weighbridge.

Pasture intake by the ponies grazing for three hours without muzzles averaged 0.8% (with some eating close to 1%) of their bodyweight, which is the equivalent of up to two thirds of the recommended daily dry matter intake for many ponies on restricted diets. Owners therefore may under-estimate pasture intakes of un-muzzled ponies, even when they are provided with restricted time at pasture. In contrast, the pasture intake of the ponies when wearing muzzles was around 0.14% of bodyweight over three hours, representing an average reduction of 83% compared to when they were not wearing muzzles.

Clare Barfoot RNutr and the research and development manager at SPILLERS said: "These figures clearly show how effective grazing muzzles appear to be as a method to restrict pasture intake. The study has given us helpful, practical guidance on how we can safely manage grass intake to control weight gain and reduce the risk of obesity-related disorders, without significantly compromising the natural behaviour and wellbeing of our horses and ponies."

Grazing muzzles must be used with care, should be properly fitted and horses and ponies should be adapted gradually to wearing them. Group and individual behaviour should be monitored closely to observe any potential concerns caused by changes to the herd dynamics. Total exclusion muzzles are not advised.

1 A Longland, ELNS, Pantafallen Fach, Tregaron, SY25 6NG, P Harris, WALTHAM Centre For Pet Nutrition, C Barfoot, Mars Horsecare UK Ltd, Old Wolverton, Buckinghamshire UK. (2011) The effect of wearing a grazing muzzle vs not wearing a grazing muzzle on pasture dry matter intake by ponies. J Equine Veterinary Science 31: 282-283

2J. Ince, Institute of Biological, Environmental and Rural Sciences (IBERS). Aberystwyth University; A. Longland, ELNS, Pantafallen Fach, Tregaron, SY25 6NG C. J. Newbold, Institute of Biological, Environmental and Rural Sciences (IBERS). Aberystwyth University & P. Harris, WALTHAM Centre For Pet Nutrition.(2011) Changes in proportions of dry matter intakes by ponies with access to pasture and haylage for 3 and 20 hours per day respectively for six weeks. J Equine Veterinary Science 31: 283

The WALTHAM® Equine Studies Group has had a record number of abstracts accepted for the Equine Science Society's forthcoming Symposium to be held in Nashville, USA, at the end of May 2011.

The WALTHAM® Equine Studies Group, headed by Professor Pat Harris MA PhD, VetMB DipECVCN MRCVS, provides the scientific support for the SPILLERS and WINERGY® brands. The Equine Science Society is a prestigious international organisation based in the USA, established to promote quality research on equine nutrition and physiology.

In fulfilment of its aims to share knowledge to help improve the health, welfare, behaviour and performance of horses throughout the world, WALTHAM®, together with its various collaborators, has had 12 abstracts accepted by the Equine Science Society to be presented at this year's Symposium. The diverse range of research topics includes studies on aspects of grazing behaviour and grass intake, gut microflora, body condition scores of competing leisure horses and the responses of ponies as well as horses to dietary glucose.

Sarah Kitson, Marketing Manager of Mars Horsecare UK said: "We are fortunate to work with many leading international research institutions, which enables us continually to break new ground in many aspects of equine nutritional science. We are all extremely proud of our achievements, not just in terms of our presence at ESS this year but also, and more importantly, in terms of the continual, practical application of our knowledge to improve the health and welfare of horses and ponies worldwide."

Recent research¹ about to be presented at a biannual nutrition meeting in the US suggests that ponies given reduced access to pasture are capable of ingesting considerable amounts of herbage during the time they are turned out and may indeed increase their intake during this time as they become accustomed to the routine.

Intake of large amounts of fructan, and other rapidly fermentable carbohydrates by grazing ponies has been linked to the development of laminitis and it has become common practice to restrict ponies' access to pasture, especially at key times of the day/year in order to reduce the risk.

The study, which was conducted at the Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, in collaboration with the WALTHAM Equine Studies Group, aimed to investigate the effect of grazing restriction on herbage intake and grazing behaviour in ponies.

The grazing behaviour of eight ponies was measured daily over a six week period to assess their voluntary intake of herbage and to monitor the effects of restricting their access to pasture. Two groups of four pony mares were used. Group A had 24 hour access to pasture while the ponies in group B had three hours of pasture access per day and were stabled for the remaining 21 hours, with ad libitum access to haylage and water.

Herbage intake was estimated during the three hours when all the ponies were at pasture by monitoring the change in weight of each individual over the period. Grazing behaviour was analysed from video footage of the two groups using interval sampling. The ponies in group B had higher estimated grazed herbage intakes than those in group A during the three hours studied and this difference was significant during the final week, when they consumed 40% of their total daily dry matter intake as grass in the three hours at pasture. This compared with an intake of grass of around 25% of their daily dry matter ingested during the first week.

Clare Barfoot RNutr and the research and development manager at SPILLERS said: "This suggests that ponies with reduced access to pasture are capable of ingesting considerable amounts of grass during the time they are turned out and may indeed progressively increase their intake during this time, indicating that the behaviour could be learned. The implication is that reducing ponies’ time out on normally managed pastures with the view to limiting the intake of rapidly fermentable carbohydrates may not be as effective as first thought."

¹J. Ince, Institute of Biological, Environmental and Rural Sciences (IBERS). Aberystwyth University; A. Longland, ELNS, Pantafallen Fach, Tregaron, SY25 6NG C. J. Newbold, Institute of Biological, Environmental and Rural Sciences (IBERS). Aberystwyth University; ;& P. Harris, WALTHAM Centre For Pet Nutrition. (2011) Changes in proportions of dry matter intakes by ponies with access to pasture and haylage for 3 and 20 hours per day respectively for six weeks. Journal of Equine Veterinary Science (in press)

Professor Pat Harris, who heads the WALTHAM® Equine Studies Group which provides the science behind the SPILLERS brand, was one of a number of eminent vets and nutritionists who contributed to the 5th European Workshop on Equine Nutrition (EWEN), held last month at the Royal Agricultural College, Cirencester in collaboration with the British Society for Animal Science and under the auspices of EAAP.

This year for the first time, an applied programme was included, aimed at sharing knowledge with horse owners to help them to understand how the latest nutrition advancements can be applied on a practical basis. Professor Harris chaired the session 'Do nutritional supplements have a role to play in my horse's diet? and gave a lecture entitled 'How can we manage those prone to laminitis - especially pasture associated laminitis'. In addition SPILLERS sponsored an applied session on 'The role of nutrition in weight management and abnormal behaviour'.

Professor Harris presented a paper on 'Recent advances in the understanding of laminitis and obesity' in the science session and was also a named author on five papers presented at the Workshop: The effect of a binding agent on occurrence of the mycotoxin Zearalenone (ZON) in equine faeces; Recent advances in the understanding of laminitis and obesity; Validation of the deuterium oxide (D2O) dilution method for the measurement of body fat content in living ponies; Comparison of two, practical weight loss protocols for the management of overweight and obese horses and ponies and the effect of water temperature on loss of water-soluble carbohydrates from hay soaked in water for up to 16 hours. Clare Barfoot BSc (Hons) RNutr, the research and development manager for SPILLERS also contributed to the latter two papers.

Professor Harris said: "The regular sharing of knowledge and ideas across all sectors of the equine nutrition industry enables us to all pull together for the common aim of continually improving equine health and welfare."

New research confirms that some obese horses and ponies may need to have their diets restricted more severely than previously thought in order to help them lose weight.

The studies were conducted by the Department of Veterinary Clinical Science at the University of Liverpool and funded by the government-initiated Knowledge Transfer Partnership and the WALTHAM Equine Studies Group. They showed that although some obese animals will lose weight, in an appropriate way, on a diet restricted to 1.25% of body weight (dry matter basis) , others may need their diet restricted to as little as 1% of body weight in order to shift surplus pounds. Such animals have been described as being 'weight loss resistant' in a recent report due to be presented at the WALTHAM International Symposium in September.

The study, which was conducted over 16 weeks, involved 12 overweight/obese horses and ponies of mixed ages and breeds, with body condition scores of between 7 and 9 (1 being emaciated and 9 being obese). They were individually housed on wood-shavings and provided with a balanced fibre-based diet at 1.25% of body weight. They were allowed daily access to a bare paddock but no structured exercise was given. Eight of the horses achieved a slow, gradual but consistent loss of body weight over the study period but weight loss was much slower in the remaining four.

These four horses, deemed to be weight loss resistant, were monitored for a further four weeks during which their diet was reduced to 1% of body weight daily. This significantly increased their rate of weekly weight loss, to a level comparable to the weight loss seen in the other eight horses in the original study. It is thought that genetics may account for such individual differences in sensitivity to weight loss. In all cases the horses remained healthy and no stereotypic behaviours were seen.

Dr Caroline Argo explains: "It is important to understand that the appetite of obese ponies will drop to around 2% of body weight (dry matter) yet their body weight will be maintained or they may even continue to gain in weight. If weight loss is to be stimulated, food intake must be limited quite severely."

Clare Barfoot BSc (Hons) RNutr, the research and development manager for SPILLERS and a member of the research team continues: "Controlled but balanced nutrition, under careful veterinary guidance, is essential to promote weight loss in overweight or obese horses and ponies, especially when exercise is not an option but we have had little evidence-based advice on how far the diet can be restricted safely to help shed weight in stubborn cases until now."

"In practice where exercise can be used to increase energy expenditure, such severe restriction may not be required; in this situation access to grazing must be reduced, exercise increased and a low calorie high fibre forage fed in a monitored way alongside an appropriately formulated forage balancer."

The WALTHAM® Equine Studies group was closely involved with this study as it has been with other ground breaking work on equine obesity, such as showing that an obese body condition score was associated with increased insulin resistance back in 2003, and developing the cresty neck scoring system.

New research, to be presented at BEVA congress this September, conducted by the WALTHAM–initiated Laminitis Consortium, indicates that soaking hay in summer temperature tap water may allow water-soluble carbohydrates (WSC) to be leached more effectively, than from winter temperature tap water, making it safer to feed to horses and ponies prone to laminitis. The study supports research carried out last year that suggested hay soaking in winter tap water may be an unreliable method.

The Laminitis Consortium comprises world-leading equine veterinary, nutrition and research experts interested in collaborating on the important topic of laminitis. It includes the authors of this work: Dr Annette Longland of Equine Livestock and Nutrition Services (ELNS), Dr Pat Harris of the WALTHAM® Equine Studies Group and Clare Barfoot of SPILLERS.

It is now well known that feeding forage containing high levels of water-soluble carbohydrates (WSC) may lead to laminitis. Many owners of laminitis-prone horses and ponies soak their hay in an attempt to reduce its WSC content, which ideally, it has been recommended, should be below 10% to make it safe to feed. However, using cold water can result in a high variability of leaching among different hays, rendering the method unreliable in terms of making hay safer for laminitics.

This work examined several different hay soaking regimens using four different types of hay. The hay was soaked at varying initial temperatures (8,16 or 49℃), over different timescales (1, 3, or 16 hours) and using a variety of soaking methods. The conclusion was that soaking hay in water at a temperature of around 16℃ for a period of 16 hours resulted in the greatest and most consistent loss of WSC. However, even then the average loss was generally less than 50% of the original WSC. Some hays in the UK contain more than 200g of WSC per kg of hay, so as pointed out by Clare Barfoot:

"Despite this exciting new research soaking hay should always be seen as an additional safeguard when it comes to feeding laminitis-prone horses and ponies. It’s crucial to have your hay analysed before feeding it to an animal at high risk of laminitis and you should always choose hay with the lowest WSC content you can find. If in doubt use a forage replacer to ensure you know exactly what you are providing."

The Laminitis Consortium is continuing its work in this area and hopes to be able to identify further practices that will be of greater benefit to the horse owner faced with hay of unknown WSC content.