<b>Protein and Energy sources with differing degradabilities for finishing steers</b> - DOI: 10.4025/actascianimsci.v29i2.225

Abstract

The objective of this study was to determine the effect of synchronization of starch (finely ground or steam-flaked corn) and protein (soybean meal or urea) rumen degradation on dry matter intake, total tract digestibility and rumen parameters of finishing Nelore steers. Four Nelore steers (300 kg LW) were utilized in a 4 x 4 Latin Square design, 2 x 2 factorial arragment: two corn processing methods (fine grinding vs. steam flaking) and two protein sources (soybean meal vs. urea). The diets contained 13% grass hay and 87% concentrate. Steam flaking decreased (p < 0.01) starch concentration in duodenal digesta, which would explain lower ruminal pH (p < 0.15) and concentration of ^N-NH3 (p < 0.01), plasma urea-N concentration (p < 0.01); and the increased molar concentration of ruminal propionate (p < 0.01). As compared to fine grinding, steam-flaking corn increased (p < 0.01) total tract digestibility of starch (98.8 vs. 88.6%), but decreased (p < 0.01) NDF digestibility (41.9 vs. 12.1%). Protein sources had no effect on the evaluated variables. Increasing starch degradability through steam-flaking of corn improved dietary protein utilization by beef steers.