Effects of stocking and supplementation rates on the performance of beef steers grazing mixed-grass prairie during the winter

Objective: The objective was to evaluate the effects of stocking and supplementation rates on steers grazing native mixed-grass prairie during the winter. Materials and Methods: Sixteen pastures (10 to 21 ha each) were selected. Treatments were arranged in a. 3 x 2 factorial: the first factor was an annual stocking rate of 39.4, 33.2, and 29.7 animal-unit-d/ha for 88 d; the second factor was supplementation at 0.9 or 1.4 kg/steer per day. Steers were fed a 43% CP cottonseed meal based pellet. Data were analyzed with an ANOVA, and the pasture was the experimental unit. Results and Discussion: The effect of stocking rate on ADG and BW per steer over the 88-d grazing period interacted (P < 0.01) with supplementation rate; ADC and total BW gain per steer (kg) responded quadratically to stocking rate with 0.9 kg/d of supplementation (P < 0.01; 0.42, 0.57, and 0.47; 40, 48, and 40, respectively), but with 1.4 kg /d of supplement, they were unaffected (P >= 0.34; 0.56, 0.53, and 0.51; 48, 48, and 46, respectively). Body weight gain per hectare (kg) tended (P = 0.08) to interact between stocking and supplementation rates, and at 0.9 kg/d of supplement, the BW gain per hectare increased quadratically (P < 0.01; 24, 32, and 32, respectively) in response to increasing stocking rate. However, with 1.4 kg/d of supplement, BW gain per hectare responded linearly (P < 0.01; 29, 31. and 35. respectively). Implications and Applications: Optimal supplementation rates with high-protein feeds interacts with stocking rate. At lower stocking rates, less supplement seems to be most beneficial. However, at higher stocking rates, more supplement is justified as evidenced by the linear increase of BW gain per hectare.