Effects of barley-based diets with 3 different rumen-degradable protein balances on performance and carcass characteristics of feedlot steers.

Damiran, D., Preston, N., McKinnon, J.J., Jonker, A., Christensen, D.A., McAllister, T.A., and Yu, P. (2014). "Effects of barley-based diets with 3 different rumen-degradable protein balances on performance and carcass characteristics of feedlot steers.", Professional Animal Scientist, 30, pp. 432-433. doi : 10.15232/pas.2014-01309  Access to full text

Abstract

The objective of this experiment was to determine the effect of varying the dietary degradable protein balance (DPB) on finishing cattle performance. Cross-bred yearling steers (n = 300; BW = 460 ± 26 kg) were allotted to 12 pens (25 steers/pen) and fed barley grain-based finishing diets with negative DPB (−12 g/kg of DM), neutral DPB (0 g/kg of DM), or positive DPB (14 g/kg of DM). The diet with negative DPB contained 88.3% barley grain and 4.7% barley silage. For the neutral and positive DPB diets, 11 and 22% of dietary barley grain, respectively, was replaced by wheat-based dried distillers grains with solubles. Increasing DPB in the diet increased the concentration of most nutrients linearly (P < 0.05), except for starch, which linearly (P < 0.05) decreased. With increasing DPB, the extent of rumen degradability decreased (P < 0.05) for OM (73.9 to 69.5%) and CP (74.3 to 68.6%), but not (P > 0.05) starch (88.3 ± 1.36%), whereas protein supply in the small intestine (78.8 to 91.2 g/kg of DM) increased (P < 0.05). Over the 131-d finishing period, DMI (11.6 ± 0.20 kg/d), ADG (1.8 ± 0.01 kg/d), G:F (0.16 ± 0.01), BW (677.8 ± 0.58 kg), HCW (397.5 ± 3.40 kg), DP (58.6 ± 0.47%), QG, and YG were similar (P > 0.05) among treatments. In conclusion, when diets were formulated to meet or exceed nutrient requirements for targeted performance, changing dietary DPB from −12 to 14 g/kg had no major effect on animal performance and carcass characteristics.

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