165 Grazing evaluation of pearlillet with and without soybean hull supplementation in a forage-finished beef production system

摘要

Pearl millet may be a viable forage option in forage-finished beef production systems due to favorable agronomic traits and nutritive value. Therefore, the objective of this study was to evaluate two varieties of pearl millet with and without soybean hull supplementation in a forage-finished beef production system. In a two-year grazing trial, sixteen 0.81-ha paddocks were randomly assigned to one of four treatments in a 2x2 factorial design: ‘Tifleaf 3’ pearl millet (PM) and ‘Exceed’ pearl millet (BMR) without and with soybean hull supplementation (0.75% of body weight (BW); PM+S and BMR+S, respectively). Each year, Angus crossbred steers (n = 32; BW = 444±59 kg) were paired to minimize variability among pairs. Pairs were randomly assigned to treatment paddocks. Grazing was initiated in June when forage was approximately 60-cm in height and terminated after approximately 90 d of rotational grazing. Average daily gain (ADG) was calculated from weights taken at grazing initiation and termination following an 18-h fast. Steers were harvested in September and carcass data were collected 24-h postmortem. All data were analyzed using PROC GLIMMIX (SAS v.9.4). Supplemented steers exhibited greater (P < 0.01) ADG than non-supplemented steers. No difference (P > 0.05) was observed for ADG between forage varieties. Pre-harvest shrunk weight, hot carcass weight (HCW), dressing percent (DP), and ribeye area were similar (P > 0.05) within supplemented and non-supplemented steers across forage varieties. Shrunk weight, HCW, and DP were similar (P > 0.05) for BMR+S and BMR. Rib-eye area was similar (P > 0.05) for BMR+S, PM+S, and PM. No differences (P > 0.05) were observed for fat thickness, adjusted fat thickness, yield grade, marbling score, or overall maturity. Results indicate pearl millet is a viable warm-season forage option for forage-finished beef systems in the Southeast and soybean hull supplementation can improve animal performance over forage alone.