KER Nutrition Studies: Measuring Nutrient DigestibilityBy Kentucky Equine Research Staff · July 31, 2014
Some of the studies conducted at Kentucky Equine Research measure the digestibility of a particular nutrient. A specific feed or forage may contain calcium, phosphorus, and protein…but are these substances truly available to the horse, or could they simply pass through the gastrointestinal tract without being absorbed? And if a particular nutrient can be provided in more than one form, are the forms equally bioavailable, or is one absorbed and used more completely than another?
To answer these question for any nutrient, the horse’s feed and hay are meticulously analyzed to see how much of the nutrient is being provided by what the horse is allowed to ingest. Samples of urine and feces are then taken each day while the horse is on the carefully measured diet. These samples are chemically analyzed for dry matter, crude protein, acid detergent fiber, neutral detergent fiber, lignin, fat, starch, water-soluble carbohydrates, gross energy, ash, and minerals.
By comparing the amount of the nutrient that the horse ingests and the amount that is recovered from waste products, it’s easy to calculate apparent and true digestibilities. If one form of a nutrient is shown to be more bioavailable than another form, feeds can be formulated to provide horses with the form that their bodies will most easily assimilate.