Effects of XXXX supplementation at varying levels of methionine and cystine on the growth performance of broilers fed reduced crude protein diets.

@entity2228 @entity2569 @entity4336 @entity4022 @entity1460
Two experiments were conducted to investigate @entity4022 addition to reduced crude protein @entity4336 - @entity1460 meal (C-SBM) diets with varying levels of TSAA achieved by varying Met and @entity2569 . The experiments were conducted with female Ross 708 broilers in brooder batteries from 0 to 18 d posthatching. Treatments had 6 replicates with 6 broilers/pen. Diets in all experiments were fed without or with @entity4022 supplementation to contain 2.32% total @entity4022 + Ser. All diets were C-SBM based and formulated to contained 1.27% standardized ileal digestible Lys supplemented with 0.20% Lys (0.394% Lys  SO(4)) and to meet or exceed the requirement of all nutrients except Met and @entity2569 where appropriate. Experiment 1 consisted of 8 dietary treatments. Three ratios of Met to @entity2569 (60:40, 50:50, and 40:60) were used on a mole for mole basis to achieve 0.063 mol of TSAA/kg of feed and a positive control with Met: @entity2569 of 50:50 at 0.76 TSAA:Lys. @entity2228 supplementation did not affect ADG or ADFI; however, G:F was increased (P = 0.003) with @entity4022 supplementation. An increase in @entity2569 and a decrease in Met resulted in a decrease (P = 0.028) in ADG but had no effect on ADFI or G:F. In experiment 2, Met was kept constant at a marginal level of 0.45% and @entity2569 was increased in 0.05% increments from 0.35 to 0.50%. @entity2228 supplementation had no main effect on ADG, ADFI, or G:F; however, @entity4022 increased G:F at the lower levels of @entity2569 but not at the higher levels ( @entity4022   @entity2569 , P = 0.031). A linear decrease (P = 0.071) was found in ADFI with increasing @entity2569 supplementation. These data indicate that @entity4022 increased G:F in female broilers fed suboptimal levels of Met and @entity2569 but not at @entity2569 levels at or above the requirement. This implies that the synthesis of @entity2569 accounts for a portion of the increased G:F observed from @entity4022 supplementation in female broilers fed reduced CP C-SBM diets.
