Abstract
In order to formulate feeds for horses, it is necessary to elucidate the content and digestibility of nutrients in feedstuffs and the requirement of nutrients of horses. Preceding the determination of nutrient requirements for the maintenance of thoroughbreds, the digestibility of nutrients of roughages, i.e. timothy, Italian ryegrass and orchardgrass hay, and hay cubes and alfalfa pellets was determined by the total feces collection method. Four male thoroughbreds 5 to 11 years old were supplied 7.8 kg feed daily and half the amounts of the rations were supplied at 8:00 and 17:00 for 10 days. Feces were collected on the last 4 days of each experimental period. Horses were supplied 7 kinds of feeds, basal feed and mixtures of basal feed and timothy, Italian ryegrass or orchardgrass hay or hay, cube or pellet alfalfa at the ratio of 1:1. The basal feed consisted of a commercial horse feed and timothy hay at the ratio of 7:3. There were differences in the content and digestibility of nutrients and calculated nutritive values, digestive crude protein (CP), total digestive nitrogen among three kinds of grass hays, i.e. timothy, Italian ryegrass and orchardgrass, but there were small differences in the above cited values among three types of alfalfa, i.e. hay, cube and pellet. The digestibility of CP increased with increasing dietary CP levels. The endogenous fecal nitrogen was estimated to be 23 g/day. The calculated true digestibility of all feedstuffs differed widely among feedstuffs.
