Q – If a horse is an easy keeper – how do we know the horse is getting all the nutrients required from their feed and are not plump for other reasons? Is there a blood test I can do?
A – Testing the blood is actually not a good way to determine nutrient status. Many metabolites fluctuate with feeding (such as protein, glucose, etc.), some nutrients have body stores so you wouldn’t even notice a deficiency until after several months when the stores are all gone (vitamin A or iron, for example), and some nutrients are extremely stable in blood thanks to hormonal control (such as calcium).
The best way to know if your horse’s diet is adequate, therefore, is to test the diet, not the blood. If the diet is adequate, you can be 99 per cent certain your horse doesn’t have nutritional problems (deficiency/toxicity), as cases of nutrient malabsorption are extremely rare.
The only way to know exactly what the horse is getting is to go through and weigh everything the horse eats in a day, have the feeds analyzed to determine nutrient composition, add everything up (nutrient content % x kg of feed consumed for Feed A + Feed B + Feed C etc.) and then compare those values to the National Research Council’s (NRC) Nutrient Requirements of Horses nutrient guidelines. You can use Excel or a similar program to help you add everything up (or just contact a nutritionist to do it for you).
Obesity – too much body fat – is ultimately caused by too many calories being consumed compared to how many are being expended (either through basic metabolism or exercise).
Some horses do naturally have slower basal metabolic rates than others (similar to people) so they require fewer calories just to maintain their body weight – and, therefore, it is easier for them to eat too many calories and gain weight. There are also medical conditions (hypothyroidism, for example) that result in a lower basal metabolic rate, thus predisposing a horse to obesity. But again, if those horses were to consume calories to meet their reduced needs, they wouldn’t gain weight. The NRC has guidelines for horses with slower metabolism to account for reduced energy needs and should be used when balancing a diet for a horse prone to obesity.
Balancing a diet for an obese horse is tricky, as you need to ensure nutrients such as protein, vitamins and minerals are met, while calories are limited. It also becomes challenging when horse owners want to feed their plump horses similarly to their lean horses (particularly at meal time).
You can be creative by feeding lower quality (energy and protein) hay, so that you can feed more of it. If you want to feed 14 mcal with hay, for example, you could feed 7kg of 2 mcal/kg hay or you could feed 8.2 kg of 1.7mcal/kg hay – I’ll bet the horse would be happier with 8.2 kg of hay rather than 7kg! You can also feed highly concentrated protein, vitamin and mineral sources (often called ‘balancers’) so that you don’t need to feed very much to pack a nutritive punch. Balancers are kind of a category between straight vitamin/mineral supplements and normal feed. They come in a pellet form and are available from the major feed companies. You can also get sneaky by offering things like hay cubes or beet pulp at ‘meal time’ to trick your plump horses into thinking they are getting some grain, but at a lower energy density than grains.
If you have an overweight horses (and studies suggest that about 50 per cent of horses are overweight!), you should work closely with an equine nutritionist to help you balance your horse’s diet to reduce the calories consumed while ensuring other nutrient needs are being met.