Limited creep-feeding supplementation effects on performance of beef cows and calves grazing limpograss pastures

Abstract

Limpograss (Hemarthria altissima) is a warm-season grass used by cow–calf producers in South Florida; however, limpograss protein concentration may limit animal performance. The objective of this study was to test the effects of creep-fed protein supplement on performance of cow–calf pairs grazing limpograss pastures. The experiments were conducted in Ona, FL from June to September 2011 (Experiment 1) and from June to August 2012 (Experiment 2). Twenty-four cows and calves [Angus-sired calves on crossbred cows (approximately 63% Bos taurus and 37% Bos indicus)] were randomly distributed in eight limpograss pastures (1.0ha/pasture). In Experiment 1, calves received 200g/d of soybean meal (SBM, 48% CP) daily by creep-feeding or no supplement (control). Treatments were distributed in a randomized complete block design with four replicates. In Experiment 2, calves received 200 or 400g/d of SBM daily by creep-feeding or no supplement (control) distributed in a randomized incomplete block design with three replicates for 200g/d and control and two replicates for 400g/d. In Experiment 1, there was no difference in HM (P=0.54; mean=4500±800kg/ha), in vitro digestible organic matter (IVDOM; P=0.92; mean=62±1.4%) and crude protein concentration (CP; P=0.14; mean=14.3±0.9%) between treatments. In addition, there was no difference in cow and calf ADG (P=0.51; mean=0.25±0.1kg/d and P=0.24; 0.55±0.1kg/d for cows and calves ADG, respectively). In Experiment 2, there was no effect of creep-feeding on HM (P=0.28; mean=6800±700kg/ha), IVDOM (P=0.31; mean=52±3.5%), and CP (P=0.63; mean=11.1±0.5%) concentrations; however, there was a linear (P=0.03) increase in ADG from 0.33 to 0.62kg/d for calves receiving from 0 to 400g/d SBM. Cow ADG was similar among treatments (P=0.44; mean=0.23±0.12kg/d). Calves receiving 400g/d SBM had 0.75kg BW/kg feed added gain efficiency {[BW gain of creep-fed calves (kg) – BW gain of control calves (kg)]/[amount of feed consumed during the experimental period (kg)]}, and a tendency for 70% linear increase in economic return (P=0.06), when compared with the control calves. Limited creep-feeding of SBM supplement may be an effective management practice to improve weaning weights of beef calves on limpograss pastures.