Digestibility and Rate of Passage by Steers Fed Tall Fescue, Alfalfa and Orchardgrass Hay in 18 and 32 C Ambient Temperatures1

Abstract

Digestibility and ingesta rate of passage were determined with Holstein steers fed chopped tall fescue “Festuca arundinacea Schreb,/alfalfa “Medicago sativa” and orchardgrass “Dactylis glomerata” hay in 18 and 32 C temperatures. Steers fed alfalfa ate more and drank more water than steers fed orchardgrass or fescue; alfalfa was more digestible. Digestible dry matter (DDM), water intake and mean retention time (MRT) increased as temperature increased. Maximum excretion rate (MER) and MRT, determined by using 144Ce, were not related to voluntary forage intake. The data indicate that if gut fill is a regulating mechanism in the intake of forages as suspected, then MRT and MER are not good estimates of gut fill.