Evaluation of oats incorporated into annual ryegrass on performance of beef cattle

Forty crossbred beef steers (204.1 + 18.9 kg BW) were used in a randomized complete block to determine the effects of incorporating oats (Avena sativa) into annual ryegrass (Lolium multiflorum) pastures. Ten warm-season perennial pastures (1.21 ha) were killed with glyphosate and then burned, after which pastures were scratched with a disk. Pastures were randomly assigned to 1 of 2 treatments: 1) oats drilled into the pasture at a depth of 2.54 cm, at a rate of 90 kg/ha, after which annual ryegrass was broadcast at the rate of 56 kg/ha (OATS) or 2) annual ryegrass broadcast at the rate of 56 kg/ha (RG). Fertilization rates and application were similar across both treatments. When pastures had sufficient forage to support 4 beef cattle (5 kg forage DM/kg of BW), cattle were weighed and then moved into pastures. Forage biomass was determined weekly with the use of a rising plate reader, and when forage became limiting (less than 5 kg of forage DM/kg of BW), cattle were weighed and then removed. Between forage grazing periods, cattle had access to a commercial feed supplement and dormant forage. Pasture cost of establishment per hectare was greater for OATS (P = 0.001; US$332.5 and $219.7 for OATS and RG, respectively). Average daily gain did not differ (P = 0.90) between treatments (1.00 vs. 0.99 kg/d for OATS and RG, respectively. Pastures planted with OATS had more grazing days (124 vs. 98) and overall greater gain per pasture (P = 0.003; 383.8 kg compared with 291.6 kg for OATS and RG, respectively). Pasture-only cost of gain was similar (P = 0.24) for both OATS and RG; however, when the cost of supplementation (when not grazing) was factored into the overall cost of gain, OATS had a more economical cost of gain compared with RG (P = 0.002). Results suggest incorporation of a small grain such as oats may increase the winter grazing period and reduce cost of gain.