PSIII-7 - Feeding effects of whole soybeans and roasted soybeans in feedlot steers

Abstract: A feedlot study was conducted to evaluate the effect of using whole (WSB) or roasted (RSB) soybeans, soybean meal (SBM), distillers grains (WDGS), or dry-rolled corn (DRC) control (CON) in finishing cattle diets on performance and carcass characteristics. Crossbred steers (n = 400, initial BW = 431kg ±1.06kg) were utilized in a generalized, randomized block design with 10 steers per pen and 8 replications per treatment with 5 treatment diets. Diets were formulated to provide the same metabolizable protein across the treatments. Final diets contained 6% supplement (aside from the CON diet, which contained 9% supplement) and 20% corn silage on a dry-matter basis. The CON diet only included DRC (71% of diet DM) and the addition of 1.5% urea. The SBM diet contained 9% (diet DM) soybean meal and 65% (diet DM) DRC, and a supplements blend that included 0.5% urea. The WSB and RSB treatments contained soybeans at 10% of diet DM and 64% DRC with 1% urea. The WDGS diet contained 12% (diet DM) of WDGS,62% (diet DM) DRC, and 1% urea. Treatment diets were fed for 132 days. Performance and carcass data were analyzed using the MIXED procedure of SAS with pen as the experimental unit and block as a fixed effect. Liver abscess presence data were analyzed as a binomial distribution using the PROC GLIMMIX procedure of SAS. Feeding RSB resulted in greater hot carcass weight (HCW), final body weight (FBW), average daily gain (ADG), 12^th rib fat thickness (P < 0.01), and marbling score (P = 0.01) than the WSB and CON diets, with no difference to the SBM and WDGS treatments. Cattle fed the RSB diet also had increased intakes over the WSB diet (P < 0.01), however, both WSB and RSB treatments resulted in superior feed efficiency than the CON and WDGS diets (P < 0.01). Feeding the WSB and RSB diets resulted in no different performance and carcass characteristics from the WDGS and SBM diets for HCW, final BW, ADG, marbling score, and LM area. LM area was the greatest in WSB fed cattle, which was significantly greater than the CON diet (P = 0.03). There was no difference in liver abscess occurrence across treatments (P = 0.56). These data suggest that feeding soybeans to finishing cattle increase ADG and feed efficiency compared to a DRC with urea diet and improve feed efficiency compared to using WDGS. Feeding whole or roasted soybeans resulted in greater gains and feed efficiency than other treatments. Roasted soybeans may be an appropriate alternative to distillers grains for finishing cattle without impacting performance or carcass characteristics.