Influence of different nitrogen sources on the digestibility of diets based on sugarcane

Abstract

In order to evaluate the effects of different nitrogen sources (soybean meal - FS, corn gluten meal - GL, and urea - UR) on the digestibility of diets based on sugarcane, five rumen fistulated crossbred cattle, four years old and 470 kg mean live weight (LW), were used in a completely randomized block design experiment, with five treatments: T1, 99.25% sugarcane + 0.75% UR; T2, 93.24% sugarcane + 6.76% FS; T3, 95.87% sugarcane + 3.79% FS + 0.34% UR; T4, 94.78% sugarcane + 5.22% GL; and T5, 96.77% sugarcane + 2.88% GL + 0.35% UR, and four replications in time. Digestibility coefficients were determined using chronic oxide as an external indicator, as were digestible energy (DE) content and total digestible nutrients (TDN). The nitrogen sources had no effect (P>0.05) on digestibility coefficients of dry matter (DM), crude protein, crude fiber, ether extract, neutral detergent fiber, acid detergent fiber, nitrogen-free extract, and organic matter, nor on TDN content, but the digestibility of gross energy was influenced (P < 0.05) by nitrogen sources, means being 76.0 and 66.75% for T4 and T1, respectively. The DE value was also influenced by nitrogen sources, T4 (3.89 Mcal/kg DM) being higher (P<0.01) than T3 (3.37 Mcal) and T1 (3.18 Mcal). The daily intake of sugarcane DM (% LW) varied from 1.03 (T5) to 1.28 (T2) without significant differences (P>0.01).