Performance, digestibility, carcass characteristics, and blood parameters of backgrounding and finishing beef steers fed diets containing corn silage or barley straw with or without calcium oxide

The effect of adding unhydrated calcium oxide (CaO) to corn silage (CS) or barley straw (BS) in a total mixed ration on growth performance, digestibility, blood parameters, and carcass characteristics was evaluated in backgrounding and finishing beef steers. Sixty Angus × beef steers were fed one of 4 diets, containing CS or BS (replacing CS at 12% diet dry matter (DM)) with or without 1% DM CaO replacing CaCO 3 . During backgrounding, CaO reduced ( P ≤ 0.04) weight gain, average daily gain, and gain:feed while only final body weight was reduced ( P = 0.05) during finishing. Feed efficiency and diet digestibility were greater ( P ≤ 0.05) for CS than BS diets. During backgrounding and finishing, CaO increased ( P = 0.02) crude protein and reduced ( P < 0.01) neutral detergent fibre digestibility, respectively. Adding CaO to the backgrounding diet increased ( P ≤ 0.01) serum amyloid-A and serum cortisol concentrations. The CaO reduced ( P ≤ 0.02) hot carcass weight and dressing percentage compared to control, while BS reduced ( P ≤ 0.02) ribeye area and grade fat compared to CS. Substituting BS for CS and including CaO decreased feed efficiency, carcass yield, and income over feed cost in feedlot steers.