Effects of variable nitrogen fertilization rates and dried distillers grains plus solubles supplementation on forage use, animal performance, and economic outcomes of steer calves grazing winter wheat pastures.

With the continued increase of fertilizer prices, stocker cattle producers may utilize alternative management strategies to mitigate costs and extend the grazing season to achieve better utilization of a wheat (Triticum aestivum L.) crop. One potential strategy is to reduce pasture nitrogen (N) fertilization rates combined with animal dietary supplementation. In this 3-year (yr) study, wheat pastures (1.62-hectare (ha)) were stocked at fixed rates of 2.47 and 4.94 steer/ha in the fall and spring respectively. Nitrogen was applied as urea to experimental pastures at three different rates: 1) 100.9 (100N), 2) 134.5 (135N), and 3) 168.1 kg N/ha (168N). These pastures were compared to pastures with a N application rate of 100.9 kg N/ha stocked with steer calves supplemented dried distillers grains plus solubles (DDGS) at 1.0% body weight (BW; 100S). In the spring, 100S pastures produced greater (P ≤ 0.05) mean and final forage mass (FM), as well as the greatest slope change in FM. Fall average daily gain (ADG) was decreased (P ≤ 0.05) in 168N pastures, while 100S produced greater (P ≤ 0.001) spring grazing days (d), weight gain/ha, and final BW. Both 100S and 168N produced a greater (P ≤ 0.05) number of combined grazing d, with 100S yielding an additional 13 d. Additionally, steers assigned to the 100S treatment produced greater (P ≤ 0.001) combined weight gain/ha. Blood urea nitrogen (BUN) concentrations on D28 were greater (P ≤ 0.001) for steers on 100S pastures and were slightly in excess of the range for maximized growth. Total spring income/ha was greater (P ≤ 0.05) for 100S and 168N, with 100S making an extra $82.38/ha compared to 100N. Calf management and feed costs were greater (P ≤ 0.001) for 100S and resulted in an increase of costs $514.60/ha above 100N. Net returns were greater (P ≤ 0.05) for 100N and 135N, with 100N netting the greatest returns, which averaged $361.00/ha more than the net return for 100S due to feed costs. Due to a substitution effect, an additional 525 kg dry matter (DM)/ha of FM was available, indicating that pastures could be stocked with an additional steer for every 2.81 ha increase in 100S pasture size, potentially providing additional economic benefits. Results from this study indicate that while DDGS supplementation provided benefits to steer and pasture performance in the spring, it was not beneficial to overall economics within the scope of the research scale production system.