Rhodes grass hay (Chloris gayana) or alfalfa hay (Medicago sativa) for calves, under diets with two levels of protein. I. Digestibility

Abstract

Sixteen male mixed breed calves, with 55-65 kg body weight and about 3 months old, were used in digestion trials with the following treatments, arranged in a 2 x 2 factorial randomized blocks design: A) Rhodes grass hay and concentrates, 13% CP; B) Rhodes grass hay and concentrates, 17% CP; C) alfalfa hay and concentrates, 13% CP; D) alfalfa hay and concentrates, 17% CP. The concentrate: roughage proportions used were 20%:80% in the first digestion trial and 40%:60% in the second one, developed immediately after. Results with 20% hay showed better N retention (44.2%, and higher protein digestibility (71.9%) but lower fiber digestibility (37.1%) than with 40% hay (30.0%, 66.8% and 52.6% respectively). Fiber was better digested in 17% CP level (60.0%) than in 13% CP level (42.4%) inside the 40% hey proportion; within 20% hay proportion the dry matter digestibility for alfalfa hay treatment (78.9%) was higher than for Rhodes hay treatment (66.5%), inside the 17% CP level.