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

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 (1.0 ha/pasture). In Experiment 1, calves received 200 g/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 400 g/d of SBM daily by creep-feeding or no supplement (control) distributed in a randomized incomplete block design with three replicates for 200 g/d and control and two replicates for 400 g/d. In Experiment 1, there was no difference in HM (P=0.54; mean=4500 +/- 800 kg/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 +/- 0.1 kg/d and P=0.24; 0.55 +/- 0.1 kg/d for cows and calves ADG, respectively). In Experiment 2, there was no effect of creep-feeding on HM (P=0.28; mean=6800 +/- 700 kg/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 0.62 kg/d for calves receiving from 0 to 400 g/d SBM. Cow ADG was similar among treatments (P=0.44; mean=0.23 +/- 0.12 kg/d). Calves receiving 400 g/d SBM had 0.75 kg 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. Published by Elsevier B.V.