Utilization of rumen protected lysine and methionine in beef feedlot diets: Impacts on steer performance

Authors: 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
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2024
Publication Date: 9/13/2024
Citation: Neville, B.W., Oliver, W.T., Wells, J., Crouse, M.S., Lindholm-Perry, A.K., Thorson, J.F., Kuehn, L.A., Freetly, H.C. 2024. Utilization of rumen protected lysine and methionine in beef feedlot diets: Impacts on steer performance [abstract]. Journal of Animal Science. 102(Supplement 3):732. https://doi.org/10.1093/jas/skae234.099.
DOI: https://doi.org/10.1093/jas/skae234.099

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. Beef steers [n=161; body weight (BW) = 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 to 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 BW were unaffected by treatment (P >/= 0.24). Average daily gain for POS (1.93kg/d P