108 Economic performance of stocker cattle grazing wheat pasture supplemented with distiller’s grains compared to varied nitrogen fertilizer rates

Abstract

With increased costs of nitrogen (N) fertilizer, other N delivery routes may be utilized to capitalize on price differences to improve economic performance of stocker cattle grazing winter wheat. The objectives of this study were to observe how dried distiller’s grains plus solubles (DDGS) supplementation and varied N fertilization rates impacted steer, stand, and economic performance. From fall 2021 to spring 2024, 725 beef steers weighing 267.41 ± 40.25 kg were grazed at the Livestock and Forestry Station near Batesville, AR, with 24, 1.62-ha pastures established using no-till methods and planted the first week of September. Nitrogen was applied as split applications of 50% at fall planting, and 50% prior to spring greenup. Steers were weighed on arrival, turnout, every 28 days following turnout, and when removed from pasture. Steers were removed from pasture when temperatures became too cold for regrowth to occur, or when forage turned reproductive. Steers were stocked at rates of 2.47 and 4.94 hd/ha in the fall and spring, respectively. During the spring of year 3, blood urea nitrogen (BUN) was measured at day 0 and day 28 of grazing. Sample dates for forage mass and quality coincide with weigh dates. Treatments consisted of 3 yearly application rates of N along with an additional treatment at the lowest N rate supplemented with DDGS. Treatments were: 100N, 135N, 168N, and 100S. Pairwise comparisons within the Mixed Model procedure in JMP were used to compare treatment responses between N rates, with year as a random effect and N rate as a fixed effect. The only difference observed between unsupplemented N rates was an increase (P < 0.05) in spring grazing days for 168N and 135N. The Mixed Model procedure followed by a Dunnett’s test was used to compare N rates against DDGS supplementation with 100S set as the positive control, with year set as a random effect. Neither animal nor economic performance improved with supplementation in the fall. During the spring, DDGS supplementation resulted in greater (P < 0.05) number of grazing days, final forage mass, weight gain/ha, average daily gain (ADG), D28 BUN, combined grazing days, and greater (P < 0.05) combined weight gain/ha and total spring income compared to all unsupplemented treatments. While 100S improved spring animal performance, 100S had the greatest (P < 0.01) calf management and feeding costs, resulting in overall decreased (P < 0.01) net returns. Supplementation was determined to become economically favorable if pasture size was increased beyond what was possible during this study since increased forage accumulation would allow for greater stocking rates. While DDGS supplementation improved overall steer and stand performance during the spring, increased costs associated with supplementation hindered overall economic performance within the studied conditions.