Abstract This study evaluated how varying crude protein levels in rations that incorporated canola meal or wheat-based dried distillers’ grains as alternative protein sources affected growth performance, carcass traits, and liver mineral status in feedlot bison heifers. Ninety-six crossbred bison heifers (initial body weight; 215.5 ± 22.2 kg) were stratified by weight and randomly assigned to one of three dietary treatments: 1) a conventional control diet (CON), 2) CON with canola meal (CM), or 3) CON with wheat-based dried distillers’ grains with solubles (WDDGS). Diets were fed over a 302-d period, consisting of a 122-d backgrounding phase and a 180-d finishing phase. During the backgrounding phase, CM and WDDGS diets were formulated to 14.0% crude protein (CP) compared with 10.0% in the CON diet. In the finishing phase, CM and WDDGS diets were formulated to 14.0% CP compared to 12.5% in the CON diet. The dry matter intake (DMI) was lower (P = 0.04) in heifers fed CM and WDDGS (5.9 kg/d) compared to CON (6.2 kg/d) during backgrounding. However, average daily gain and gain-to-feed ratio did not differ among treatments in any phase (backgrounding, finishing, or overall; P ≥0.27). Final body weight, hot carcass weight, dressing percentage, ribeye area, backfat thickness, marbling occurrence, and liver abscess incidence were not affected by dietary treatment (P ≥0.20). Hepatic copper (P = 0.02) and zinc (P = 0.03) concentrations were greater in heifers fed by-product diets compared to CON. A pronounced seasonal pattern in DMI was observed with a peak occurring in summer and a nadir in the winter. These results indicate that bison heifers can achieve similar growth performance and carcass characteristics when fed diets formulated to 10.0% CP during backgrounding and 12.5% CP during finishing, and that increasing dietary CP to 14.0% through the inclusion of CM or WDDGS did not enhance productivity. These results indicate that CM or WDDGS can be fed as protein sources without compromising the performance of bison heifers.
Binetruy et al. (Sat,) studied this question.