Hands-On Horse Research: How Is Nutrient Digestibility Expressed?

Nutrient digestibility is expressed as apparent digestibility. Apparent digestibility is the nutrient content found in the feces subtracted from the nutrient content in the feed. The resultant number is then divided by the total daily intake of the nutrient. This produces a percentage that represents the apparent digestibility.

Apparent digestibility is the sum of nutrients that remain undigested during their journey through the digestive tract plus that which may have been sloughed off from the intestinal wall and then excreted in feces. Fecal nutrients that originate from within the horse are termed endogenous. Due to endogenous losses, an underestimation of digestibility occurs.

True digestibility value does not include endogenous losses. True digestibility can be determined by using statistical procedures that test a range of nutrient intakes.

Learn more about KER’s research program here.