Over-feeding is often cited as the main cause of equine obesity but this implies a positive action on the part of the owner to give the horse too much feed. In many instances, however, it is the opposite ie. a lack of action, to prevent the horse or pony consuming too much grass or forage or to keep the animal exercised, which are to blame. In order to explain why this inaction on the part of the owner can have such serious implications, it’s worth taking a look at equine physiology.
Before domestication, horses evolved to be constantly foraging and moving around to find food. Many, especially Native breeds, have adapted to thrive on the poorest grazing and all are programmed to put on weight when food is more readily available in the spring and summer. These excesses are stored as fat, to provide energy for the animal through the winter, with the fat deposited throughout the body, especially the abdomen (tummy), where it is known as omental fat.
Recent research has shown that these fat cells, originally thought to be benign energy stores, do actually produce hormones which regulate a number of body processes and play a key role in helping horses and ponies survive harsher conditions. One such hormone is cortisol, which inhibits the action of insulin, the hormone responsible for controlling blood glucose levels. The result is a degree of insulin resistance which is normally of benefit as it ensures glucose is available for essential areas, like the brain, at the expense of less essential tissues, like muscles.
This condition pervades through the winter but gradually lessens as the animal loses weight, and omental fat, with the naturally reduced availability of food and colder weather conditions. By spring time, the horse is lean but healthy and ready to indulge in the pleasures of spring grazing and gaining weight for the following winter. The trouble is, these fluctuations in a horse or pony’s condition are no longer acceptable, nor suitable, for the modern owner whose requirements for performance or breeding are less satisfactorily met by a horse who spends 6 months of the year in poor condition.
The problem with not allowing a fat equine to lose weight through the winter is that the insulin resistance, resulting from cortisol production, is not reversed. When allowed to continue long-term, this can result in a condition now known as Equine Metabolic Syndrome, giving rise to elevated levels of glucose and insulin in the blood and, ultimately, a greatly increased risk of laminitis. So how do we adapt our husbandry and feeding practices to best suit our own needs, whilst acknowledging a horse’s unchangeable physiology?
Controlling calorie intake
For most good-doers, there is no getting away from the vigilance and creativeness required to prevent the weight gain that comes so naturally during the summer months. This means continuously controlling calorie intake while maintaining fibre intake at a minimum of the equivalent of 1% of bodyweight (ie. around 5kg for a 500kg horse or 3.5kg for a 350kg pony) per day to ensure gut health and efficiency.
So high calorie, relatively low fibre spring grass is only allowed in moderation unless, of course, the demands of work mean that your horse or pony burns off all the calories he consumes so does not store any as fat. Horses who need to lose weight must burn more calories than they eat and a target reduction of 25 – 30 kg of bodyweight over 4 to 6 weeks is ideal. Regular weighing or weightaping can be useful, with results plotted on a graph being helpful by giving a visual representation of progress.
The importance of exercise is frequently forgotten yet, when an owner has insufficient time or wherewithal to keep a horse or pony active, it is perhaps prudent for them to reconsider the whole issue of horse-owning itself. Of course, age, injury or motherhood may naturally inhibit exercise but creative owners will find a way to keep horse sufficiently on the move to aid good health. Larger, rather than, smaller turnout areas, tying several haynets around the box or paddock and positioning feed and water buckets at opposite ends will, at least, mean a horse has to move around to eat and drink.
As well as controlling the amount of grass or forage a horse gets, we should also look at its nutritional contribution. Late-harvested hay or haylage has more stalk and less leaf, making it both less digestible and less nutritious but ideal for good-doers. This fibrous forage helps meet fibre requirements with fewer accompanying calories and also takes some chewing, helping to satisfy a horse’s physiological need to eat for 18 hours a day. Using small-holed haynets and/or one net inside another, will also extend eating time, help smaller portions last longer and avoids a horse or pony suffering prolonged periods without forage. A low calorie chaff, such as Baileys Light Chaff, or Speedi-Beet can also be fed as an additional fibre source.
No equine should ever be starved as this can cause digestive upsets, or worse, so, like all changes to the diet, where a drastic reduction in food intake is necessary, it should not be too abrupt. Hyperlipaemia is a condition that arises when the body is starved of energy and excessive fat is mobilised to compensate. As a result, free fatty acids and triglycerides are released into the blood stream and, in excess, can cause liver and kidney failure. Prolonged periods without food are, therefore, not only risky but will also increase the likelihood that the horse eats more voraciously when grass or forage is available.
Scientists now acknowledge that much modern pasture and arable land no longer contains the mineral and nutrient levels it once did. This means that today’s grass, forage and grain may provide plenty of calories but are likely to be deficient in vitamins, minerals and other nutrients, like protein. Whilst we may believe that good-doers, particularly Native ponies, can survive these inadequacies, the physical demands of performance, breeding and even healing will probably leave the pony wanting, unless some form of supplementary feed is given. This is where feed balancers, like Baileys Lo-Cal balancer come into their own, providing essential nutrients, including vitamins, minerals and quality protein, but without the calorie content of a “conventional” mix or cube.
Good quality protein provides essential amino acids which the body requires to build and maintain muscle tissue, a healthy coat and strong hooves. Vitamins and minerals are also involved in body structure and function, including metabolism and hoof growth and without them a horse can simply look and feel “below par”. Indeed, many a “lazy” overweight pony who receives little or no hard feed will soon gain enthusiasm for work when receiving all the nutrients he needs from a balancer alongside his forage.
An aesthetically pleasing rounded top line should come from correct work coupled with the right dietary building blocks to build muscle tone rather than fat. Whilst you may not wish to see a horse’s ribs, you must easily be able to feel them and “fat pads”, which are notoriously hard to shift, are a no-no! Feeding a balancer throughout the year means you can be sure that your horse is getting all the essential nutrients he needs while you control his energy (calorie) intake according to workload and time of year. If you must keep your good-doer “warm”, rugged and stabled through the winter, you should be even more vigilant about his waistline during the summer as you are reducing the chances of “natural” winter weight loss.
So there’s nothing wrong with wanting to avoid the seasonal fluctuations in a horse’s condition but the aim is to maintain the right condition rather than the overweight condition. With the advent of balancers, a horse need not miss out on essential nutrients while on a “calorie-controlled” diet. A horse or pony receiving a fully balanced diet will always be in a better position to meet the demands placed on him, including doing the exercise required to maintain a healthy body condition. Our requirement to keep a horse consistently in “better” condition should be of benefit to his or her welfare rather than detrimental to it and those owners who err towards the larger side of “better” should consider the welfare implications of their actions.