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Effect of the addition of calcium oxide in soybean hull and non-soybean hull based beef diets on feedlot performance and carcass characteristics
The acidic nature of dried distillers grains with solubles (DDGS) is a key determinant in depressing fiber and protein digestibility and plays a primary role in decreased intake and growth rate when DDGS concentrations exceed 30% of the diet DM. We hypothesized that addition of soybean hulls (SBH) and/or calcium oxide (CaO) to rations containing DDGS would increase rumen pH, enhance fiber digestibility, and improve steer performance. Angus x Simmental steers (n=112, BW=364.4 kg, SD=7.87) were allotted to 1 of 4 diets arranged as a 2x2 factorial to determine the effect of SBH and CaO on performance of steers fed 20% corn stover and 30% DDGS. Soybean hull diets contained 30% SBH and 14.1 or 15.0% corn, whereas corn diets contained 43.9 or 44.8% corn. Calcium oxide diets contained 1% CaO and non-CaO diets contained 1.9% limestone. Diets were fed once daily at 0800 until steers achieved a target BW of 628 kg. Statistical analyses were conducted using the MIXED procedure of SAS. Weights did not differ among treatments throughout the study (P ≥ 0.46). Overall carcass adjusted gain did not differ due to SBH or CaO inclusion (P ≥ 0.13), but there was an interaction (P = 0.01) where CaO improved gain of steers fed corn, but not steers fed SBH. Steers fed SBH consumed more than steers fed corn (P = 0.02) and an interaction tended to occur (P = 0.06) where CaO increased DMI of steers fed corn, but not steers fed SBH. An interaction occurred for gain:feed during the last 62 d of the study, where CaO increased gain:feed in steers fed corn (P = 0.02), but not in steers fed SBH. Overall, gain:feed did not differ among treatments (P = 0.36). Calcium oxide increased hot carcass weight and yield grade (interaction; P ≤ 0.04) and tended to increase backfat (interaction; P = 0.08) in steers fed corn, but not in steers fed SBH. Dressing percentage, L. dorsi area, %KPH, and marbling score did not differ among treatments (P ≥ 0.14). Steers fed SBH tended to have a greater percentage of carcasses grade select (P = 0.09) and fewer grade choice average (P = 0.02) compared to steers fed corn. In conclusion, CaO appears to enhance performance of cattle fed DDGS + corn stover diets when corn is a primary component of the diet, but not when corn is partially replaced by a fiber based energy feed.
Keywords: Steer, Calcium Oxide, Performance