Fit and not fat - Is body condition important to racing performance? | Trainer Magazine | European Trainer Article Index

Nov 25

Nov 25 Fit and not fat - Is body condition important to racing performance?

Performance is linked to lean body mass For a horse to become overweight, there has to be a period of time where its energy consumption (calories in) is greater than their energy expenditure (calories used), which is simply a function of what is fed versus daily activity, including exercise. It is unfortunate that as the result of the vagaries of the European feeding stuffs legislation, one of the most useful pieces of information for a trainer about a their feed, i.e. its energy content as digestible energy (DE), cannot legally be provided as part of the statutory label declaration. Instead, the DE value is usually found somewhere else on the bag, on the website, or only by making a phone call to the particular feed company concerned. In youngstock, the combinatio n of a plentiful supply of grass and good forage and concentrate feeds can lead to animals becoming overweight relatively easily. Horses in pre-training may arrive with the equine equivalent of ‘puppy fat,’ which can also be the result of over-conditioning during sales preparation. Whilst the impetus is for youngsters to look their best for the sales ring, there is a balance to be achieved between fit and fat, as overweight yearlings simply cause issues for trainers and pre-trainers in their need to normalise body condition. Whilst horses in full training are rarely described as being very overweight, they may be overweight for the job of racing. Trainers are generally very aware of the influence of bodyweight on racing performance and so strive to ensure that their horses reach the Should we really be worried about obesity in racehorses? A quick glance around the paddock of most racetracks in Europe would suggest not. However, whilst the number of horses racing with a much higher than optimum body weight may be low, this doesn’t represent the full story. When evaluating racehorse feed management, it is not uncommon for a nutritionist to hear the words “I have to work the horses harder to keep the weight off.” Also the question of over-conditioning in youngstock should perhaps be discussed in the context of its effect on horses once in training. racecourse in optimum body condition. A body condition score of no more than 4 to 5 on a scale of 1 to 10 is generally regarded as being optimum for intense exercise such as racing. Body condition score assesses flesh coverage, mostly fat, over the various areas of the body and a score of 1 is extremely thin and 9 is obese. Studies in human athletes and also more recently in horses suggest that performance is linked to lean body mass, or in other words, muscle. This makes absolute sense, as the greater the extent of the muscle mass, the higher the power-to-weight ratio becomes, which is important for intense exercise. Any large deviation in body condition score away from 4 to 5 in either direction is detrimental to performance. A significant fall in body condition score below 4 can mean the loss of lean tissue as well as fat and conversely a horse with a body condition score above 5 is probably carrying too much fat, which will reduce its power-to-weight ratio. Feed less, don’t exercise more It should theoretically be much easier to maintain a horse in training at ideal body condition, as we are firmly in charge of what they are fed. Some horses in training do however rise above their ideal body condition for racing and this can happen for a number of reasons. The most common reason for sub- optimal body condition is that horses are not fed as individuals and their feed intake is not adjusted sufficiently to compensate for other factors. Whilst a minimum amount of forage needs to be fed regardless of activity level (1- 1.25% of bodyweight), this needs to be balanced with an appropriate amount of concentrate feed to prevent horses being underweight or overweight. Concentrate feed intake may actually need to be reduced if forage quality is particularly good, or if the horse concerned is proving to be a particularly good doer. Feeding by the scoop rather than by weight can also be an issue. Although cubes are convenient and a good choice, they are relatively easier to overfeed, as a bowl of cubes is significantly heavier than a bowl of mix. The difference, for example, between a flat and heaped scoop of cubes over time can make a big difference to energy intake. Another racing myth that needs to be exploded at this point is the idea that horses are not ready to race unless they are eating a certain poundage of feed. Different horses will require varying amounts of feed at different stages of training and generalisations are risky. Equally, the level of work should always be exclusively dictated by your training needs and should not be regarded as an additional method to reduce body condition. We should banish the thought that you have to work some horses on some manufacturer’s feeds harder to prevent them from getting fat – just feed less concentrate. Obesity brings physical and metabolic issues Why is it that being overweight can be a problem for mares, youngsters, and horses in training? In broodmares, obesity can contribute to difficulties during foaling, and research in other species suggests that it may also adversely affect foal birth weights and lactation. Research in horses has also established a link between obesity and insulin resistance. Insulin resistance describes the condition when the body’s cells become lazy to the effect of the hormone insulin. This adversely affects the ability of the body to manage glucose distribution to the tissues. Insulin resistance has been linked with certain developmental orthopaedic diseases and so is The low-grade inflammatory state of obesity An excess energy intake over time leads to increased storage of energy as fat within the fat cells or adipocyctes, which increase in both number and size. Adipocytes have the ability to release stored energy store in the form of fatty acids as required. It was once believed that adipocytes were largely inactive with no widespread effects within the body. However, over recent years, research evidence in other species has emerged to suggest that adipocytes are actually very metabolically active and play a key role in the development of a number of obesity-related diseases in humans such as diabetes, artherosclerosis, osteoarthritis, heart disease, hypertension, and some forms of cancer. The theory is that when full, adipocytes release a cocktail of inflammatory substances known as adipokines such as tumour necrosis factor- (TNF- ), interleukin-6 (IL-6), and leptin, which collectively have a detrimental effect on the body. Obesity is now associated with a generalised state of chronic inflammation. Early work in horses suggests that their fat cells may also release some of these inflammatory substances which may contribute to obesity related conditions such as laminitis and metabolic syndrome. Perhaps of greater relevance to horses in training is the active area of research in humans that is investigating the potential effect of this low-grade state of inflammation on cartilage health and its implication for joint-related conditions such as osteoarthritis. Being ahead of the game My overwhelming feeling is that we should make every attempt to ensure that our horses are fit and not fat and that this should start at the very beginning of the breeding cycle. In other words, broodmares do not become obese and yearlings are not delivered to trainers carrying excess condition. This immediately reduces the need for ‘dieting’ during pre-training, and body shape will be allowed to change slowly as training progresses. Once in training, the main point to press is that if your horses are overweight, feed them less concentrate and don’t exercise them more or harder than your training program requires. Simple things like appreciating the difference in the digestible energy (DE) content between feeds and even using a smaller feed scoop can help to ensure that weight does not slowly creep on. If a weighbridge is available, use it weekly at the same time of day to record horses weights and allow someone in the yard to body condition score the horses monthly. We are at the beginning of our cycle of knowledge with respect to the inflammatory effects of obesity, and perhaps we would do well to nip this potential issue in the bud as it is such a straightforward one to resolve.

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(European Trainer - issue 36 - Winter 2011)

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