32 Determining the feeding value of corn gluten feed relative to corn when supplemented to beef calves grazed on stockpiled tall fescue pastures

Abstract

This experiment compared the performance response of supplementing corn gluten feed (CGF) or corn to calves grazing stockpiled tall fescue pastures over a 70-d period. Forty-four Angus x Simmental calves (238 ± 4 kg) were stratified across 6 treatments by BW and sex in a 2 x 3 factorial arrangement. Calves were supplemented cracked corn (n = 16) or CGF (n = 18). Calves were housed in 2 pastures and supplemented individually using the SmartFeed Pro feeding system, with all treatments represented in each pasture. Supplement DMI was programmed at 0.59, 0.87, or 1.13% BW. Calves which failed to train to the feeding system (n = 10) were treated as an un-supplemented control. Weight and flesh condition score (FCS) were recorded every 14-d, and ultrasound 12th rib fat thickness (FT) was measured on d 0 and 70. Data were analyzed with PROC GLM in SAS with supplement type as a main effect, sex as a fixed effect, and group as a random effect. Individual supplement DMI was included in the model as a covariate rather than a main effect due to high variation. Significance was defined at P ≤ 0.05 and means were separated using LSD. Initial BW, FCS, and FT were similar (P ≥ 0.12) among treatments. No differences (P ≥ 0.25) were observed in supplement DMI throughout the experiment. No differences (P ≥ 0.64) were observed in ADG and supplement G:F through 14 d. Through d 28 to 70, CGF-fed calves had greater (P ≤ 0.03) ADG and supplement G:F relative to corn-fed calves. Final FCS was greater (P < 0.01) for CGF-supplemented calves relative to those supplemented corn, though FT was not different (P = 0.87). These data indicate that supplementing CGF rather than corn yields a greater performance response in beef calves grazing stockpiled tall fescue.