Our leisure horses are getting too fat. Researcher’s surveys have indicated that up to half of our leisure horses are obese, and despite the fact that owners are known to underestimate their horse’s body fat levels, a study of 785 leisure and competition horses in thirty vet practices showed that around a third were reported by their owners to be overweight.
Clearly we need to feed our horses less dietary energy. We need to start with forage since many horses are overweight despite not being fed any supplementary feed. Pasture grass can have an energy content of 11MJ per kilo dry matter, which is equivalent to a competition horse feed. Unrestricted summer grass intake is likely to make any horse out 24/7 overweight, unless they have a poor appetite or are worked very hard. Weight loss depends on an energy imbalance, or a reduction of energy below requirements, which makes the horse use up the energy stored as fat.
Simply feeding much less of the current forage and restricting access to grass or removing from pasture is not the healthy answer. Reducing forage intake dramatically has many unhealthy effects on the horse including less time spent chewing and an increased risk of abnormal behaviour such as wood chewing and crib-biting and an increased risk of gastric ulcers.
Restricting forage intake dramatically also restricts nutrient supply to gut bacteria, which could have detrimental effects on the horse. Horses rely on healthy gut micro-organisms including bacteria for their own health and efficient immune function.
A healthier alternative is to source very low energy forage so that a more appropriate amount can be fed. Ideally, forage needs to have an energy content of below 7.5 MJ/kg dry matter for it to be useful for weight loss. Ideally at least 1.5% of bodyweight in dry matter should be fed per 24 hours. Some vets are recommending 1% bodyweight intake of forage daily for weight loss, but this is based on using a moderate to good quality forage, which is not healthy for the horse. Whilst hay can be soaked to reduce its energy content, this is no guarantee and the soaked hay should be analysed to check its energy, regardless of the original energy content.
Horses fed less than 2% bodyweight in dry matter daily should have a probiotic product e.g. one containing yeast, added to their diet to help support their gut bacteria.
Reducing dietary energy intake enough to cause weight loss in horses or ponies resistant to losing weight is likely to cause protein deficiency if the protein is not balanced carefully. If the forage has lower than 7% protein and is fed at less than 2% bodyweight per day, supplementary protein should be fed to ensure a supply of all the essential amino acids in sufficient quantities. Balancers, protein supplements or oilseed meals can be used to supplement protein.
A multi-vitamin and mineral supplement is essential to balance a restricted forage-only diet. Without it, nutrient deficiencies will develop and will eventually harm the horse.
Obesity in our horses is a health challenge we need to take action against, but we need to do so in a way that doesn’t cause other health problems.