Location: Nutrition, Growth and Physiology
Title: Utilization of rumen protected lysine and methionine in beef feedlot diets: impacts on steer performanceAuthor
Neville, Bryan | |
Oliver, William | |
Wells, James - Jim | |
Crouse, Matthew | |
Lindholm-Perry, Amanda | |
Thorson, Jennifer | |
Kuehn, Larry | |
FREETLY, HARVEY - Retired ARS Employee |
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only Publication Acceptance Date: 4/11/2024 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: Our objective was to compare intake, gain, and feed efficiency of steers fed rumen protected lysine and/or methionine in 10% crude protein diet relative to performance of steers fed a diet with 13% crude protein without added amino acids. One hundred sixty-one beef steers (429.7 ± 44.5kg) were utilized in this experiment. Calves were randomly assigned to treatments consisting of: 1) positive control diet (POS), formulated to contain 13.0-13.5% CP, 2) negative control (NEG) diet containing 10.2% CP, which also forms the basal diet for the remaining treatments, 3) rumen protected methionine (RPMet) 10.2% CP basal diet and 7.2 g/d supplemental methionine, 4) rumen protected lysine (RPLys) 10.2% CP basal diet and 18.5 g/d supplemental lysine, and 5) the combination of rumen protected lysine and methionine (RPMet+Lys) 10.2% basal diet with 7.2 and 18.5 g/d supplemental methionine and lysine, respectively. Initial and final body weights were unaffected by treatment (P >/= 0.24). Average daily gain for POS (1.93kg/d P = 0.02) was greater than those of NEG, RPLYS, and RPMET+LYS, but was similar to RPMET (1.86kg/d; P = 0.17). Dry matter intake was greater in RPMET (12.1kg/d; P = 0.10) compared to all other treatments. Gain-to-feed ratio was greatest in POS (0.170kg gain:kg DMI; P = 0.04). The impacts of rumen-protected amino acids on performance (intake, gain, and efficiency) of beef steers fed high-concentrate diets were inconsistent. Evaluating both lysine and methionine supplied independent of each other in various concentrations is critical before moving forward with recommendations for beef cattle. |