Balanced protein/energy supplementation plan for beef cattle on tropical pasture

Abstract

The objective of this study was to evaluate the effects of the amount of balanced protein/energy supplement adjusted according to the protein content of the pasture on intake, digestibility, and performance of young bulls managed on tropical pasture. Thirty-six crossbred bulls (½ Angus × ½ Nellore) averaging 8 months of age and 217.2 ± 4 kg were distributed to eight 1-hectare paddocks with tropical grass. The treatments were based on the amounts of balanced protein/energy supplement (0, 2.8, 5.5 and 7.4 g/kg of body weight - BW). The amounts of supplement were chosen to achieve dietary protein levels of 110, 130 and 150 g/kg of dry matter (DM). The increase of supplementation had a positive linear pattern (P < 0.05) on intakes of DM, crude protein (CP), organic matter (OM), digestible organic matter (DOM) and CP:DOM ratio. However, the intakes of forage and neutral detergent fiber (NDF) did not change (P > 0.05) with supplementation. The apparent digestibility of DM, OM, CP and NDF were not affected (P > 0.05) by increasing supplement amounts. Conversely, the grazing time decreased linearly (P = 0.022) with increasing supplementation. Moreover, a linear increase in the final body weight (P = 0.002) and average daily gain (P = 0.002) and, a linear decrease in the efficiency of supplement use (P = 0.021) were observed with increasing supplementation. Increasing the amount of balanced protein/energy supplementation increases the DM intake, digestibility and animal performance with no substitution effect on forage intake.