Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 12, 1999
Publication Date: N/A
Interpretive Summary: Including whole oil seed in ruminant diets may be a practical means of increasing the both the energy density of the diet plus adding supplemental protein. Earlier research, however, suggested that feeding roasted soybeans to growing steers reduced the output of growth hormone and thyroid stimulating hormone by the pituitary and resulted in reduced growth per unit of feed input. The current study determined if the feeding of roasted soybeans affected estimated carcass composition and merit in feedlot steers either implanted with Synovex-S or not implanted. In both implanted and non-implanted steers, carcass weight and the amount of fat deposited was less in steers fed roasted soybeans compared to those fed soybean meal, and carcass merit measurements were not affected. The study indicates no benefit to including roasted soybeans in diets of feedlot cattle.
Technical Abstract: Fifty-eight beef steer carcasses from three 2 x 2 factorial feeding trials (Trial 1, 20 carcasses and Trials 2 and 3, 19 carcasses each) were evaluated to study the influence of supplementing with roasted soybeans (RSB) vs. soybean meal (SBM) and implanting with the estrogenic growth promoter Synovex-S (SYN, 20 mg estradiol benzoate and 200 mg progesterone) on carcass merit, composition of dissected 9 -10-11 rib section, estimated edible carcass composition, and cooking characteristics of strip loin steaks. In all trials, steers were fed diets of 15% corn silage, 15% orchard grass silage, 70% corn-based concentrate supplemented with either soybean meal or roasted soybeans (127o C for 10 min) and either not implanted or implanted. There were no treatment interactions found in this study. Across trials, hot carcass weight was 8.3 kg less (P < 0.03) for RSB steers compared to SBM steers. Fat weight (P < 0.01) and percent fat (P < 0.01) were less and percent bone (P < 0.04) was greater in the 9-10-11-rib of RSB steers compared to SBM steers. Estimated percent fat (P < 0.02) was less and percent bone (P < 0.04) was greater in edible carcass of RSB steers compared to SBM steers. Total 9-10-11-rib weight tended to be less for RSB steers (P < 0.08). Carcass merit measurements were not different (P > 0.10) between RSB- and SBM-supplemented steers but reflected the composition data. It is concluded from these carcass data that in feedlot steers both not treated or treated with an estrogenic growth promoter, there is no benefit from supplementing with RSB in place of SBM and that the use of RSB in feedlot diets may reduce the amount and quality of edible carcass.