Effect of feed level and supplementary rumen protected lysine and methionine on growth performance, rumen fermentation, blood metabolites and nitrogen balance in growing Tan lambs fed low protein diets

Abstract Effect of feed level (FL) and supplementary rumen protected lysine (Lys) and methionine (Met) (RPLM) on growth performance, rumen fermentation, blood metabolites, and nitrogen (N) balance was studied in growing lambs fed low protein diets. Thirty-six, 7-month old wether Tan lambs (initial body weight, 35.0 ± 1.66 kg) were assigned into one of six groups (n = 6) in a randomized complete block design. The experiment was a 2 × 3 factorial arrangement of treatments. The lambs were either not supplemented (control) or supplemented (RPLM) with 4.5 g/day rumen protected Lys plus 1.5 g/day rumen protected Met and combined with three FLs (1.0, 0.8 and 0.6 voluntary intake - VI). The basal diet, on a dry matter (DM) basis, consisted of 400 g/kg forage and 600 g/kg concentrate. The average daily gain (ADG) increased linearly (P