Knowing the body weight of a horse is an essential element for many management decisions. Most horse owners and veterinarians underestimate body weight of a horse when using only visual assessment. Livestock scales are the most accurate method for determining body weight of a horse, but they are not easily accessible by most horse owners. This poses two questions for horse owners: 1) is it really that important to know the body weight of a horse, and 2) without having access to a scale are there other ways to make an educated estimate of body weight?
Importance of Knowing Body Weight
Body weight is the single most important factor needed for establishing a nutrition program for any horse. Nutrient requirements set forth by the National Research Council are based on body weight, therefore one must have at least a general idea for a horse’s body weight in order to determine the appropriate set of nutrient requirements to base rations. Body weight is correlated with nutrient requirements and total feed intake; larger horses have higher nutritional requirements and must consume more total food than a smaller horse.
Understanding body weight is also important when it comes to following label guidelines for feed. Many horse owners do not consult with a nutritionist when deciding on a feed program for their horse, therefore they must rely on the feeding instructions provided by a feed manufacturer. These instructions are required by law to be listed either on the bag or on an attached tag. Each manufacturer may list instructions in a slightly different format, but they are always based on body weight. For example, one feed tag may instruct to feed 0.5 lb for every 100 lb of body weight. Another feed tag may instruct to feed 0.5% of body weight. For both examples, that would mean feeding 5 lb per day if the horse weighs 1,000 lb. However, if a horse owner underestimated body weight, and the horse actually weighs 1,250 lb, the horse should have been fed 6.25 lb per day. If the horse owner overestimated body weight and the horse actually weighs 800 lb, the horse should have been fed 4 lb per day.
In the case of underestimating a horse’s body weight, and feeding too little, a horse can end up in a negative energy balance meaning they will begin to lose weight and drop in body condition. In the case of overestimating a horse’s body weight and feeding too much feed, a horse will begin to accumulate excess fat and may become overweight or obese. Both situations can have negative effects on the health and performance of a horse.
