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

Abstract

Eight male calves, European-zebu crosses, 80 kg to 90 kg live weight and with ruminal fistula, were used in the following 2 x 2 factorial arrangement of treatments: A) Rhodes grass hay (40%) and concentrate (60%) in a 13% CP diet; B) same than A, in a 17% CP diet; C ) alfalfa hay (40%) and concentrate (60%) in a 13% CP diet; D) same than C, in a 17% CP diet. The statistical design was a “change-over" with two groups of four animals each and periods of 4 weeks, using the fourth one to make digestion "in situ" with the nylon bags technique. Incubation times were: 3 h, 12 h, 24 h, 48 h, 72 h and 96 h. Results showed quicker degradation for the dry matter of alfalfa hay treatments than for Rhodes grass hay treatments (p < 0,05); the protein of alfalfa hay treatments was degraded more slowly (p ≤ 0,05 ) for 3 h, 12 h and 24 h incubation time). There was also an indication (not statistically confirmed) that fiber disappearance from the nylon bags was greater for 17% CP diets than for 13% CP diets.