Conducting an Equine Nutrition Evaluation: Getting the InformationBy Kentucky Equine Research Staff · March 2, 2012
Feed manufacturers and horse owners place a great deal of emphasis on the nutrient content of the feeds and supplements that they produce or feed to their horses. Often, extremely rigid values are used for certain nutrients. For instance, some horse owners will insist that they feed a 14% protein concentrate to their yearlings; 13% would be considered completely inadequate and 15% protein would be excessive. These preconceived ideas about the correct nutrient concentration for different classes of horses are more a product of tradition and misinformation than science.
In fact, the concentration of a specific nutrient in a grain mix or supplement is only relevant when it is viewed in the context of a total ration. Therefore, it is important that horsemen have a system to accurately evaluate the complete ration of the horse. Unfortunately, this is not as simple as it may first appear. Nutrition evaluations are based on a number of assumptions and estimates that may or may not be correct.
Types of Evaluations
There are two ways that you can approach a ration evaluation. One way is to evaluate a current ration for nutrient adequacy by tallying up what is currently being fed and comparing that to the horse’s requirements. This is actually more difficult than it may first appear since most horsemen don’t actually know exactly what their horses are eating. There are a number of checks that can be used to more accurately estimate feed intakes, and those will be reviewed later. A second type of evaluation is one in which a ration is being developed for a horse. These types of evaluations are also tricky because the various feeds and levels of intakes selected must be practial and safe for the horse in question.
Every nutrition evaluation should follow the same series of steps. Omitting any of these steps can lead to serious errors in an evaluation. These steps include determining the class of horse, selecting nutrient requirements, evaluating energy balance, evaluating forage portion of diet, and evaluating nutrient adequacy of the complete ration. Additionally, comprehensive evaluations should include an evaluation of existing problems that have a nutritional component as well as identifying environmental risk factors which may be managed through extranutritional supplementation.
The obvious place to start with any nutrition evaluation is by classifying the type of horse being fed. Different classes of horses have different nutrient requirements, and they will eat different amounts of forage and grain.
Horses can be classed into the following broad categories: (1) growing horses such as suckling foals, weanlings, yearlings, long yearlings, two year olds; (2) broodmares whether barren, early pregnant, late pregnant, early lactation, or late lactation; (3) breeding stallions, either idle or breeding; and (4) adult horses in light, moderate, heavy work, or idle or geriatric.
Some of these classes and subclasses have the same effective classification for determining nutrient requrirements. For example, a barren broodmare that is neither lactating nor pregnant will have the same requirements as an idle stallion or pasture pet.
Within each class of horse, it is also important to know the horse’s current body weight, its age and mature body weight if it is growing, and its rate of body weight gain or loss. For a growing horse, weight change will be due to natural development, but for adult horses, weight changes will also have a large influence on nutrient requirements. For example, an adult horse that is too thin may need to gain weight to reach a desirable body condition. This weight gain will require additional dietary calories which will increase the horse’s total daily energy requirement.
Adapted from: Pagan, J.D. 1998. Computing horse nutrition: How to properly conduct an equine nutrition evaluation. Advances in Equine Nutrition, Volume I. Nottingham University Press, Nottingham, U.K., pp. 111-123. Buy Advances in Equine Nutrition here.