The objective of this experiment was to determine if growth, carcass composition, and myofiber characteristics of lambs were affected by heterozygosity for a myostatin mutation (g+6723G>A) when offered differing allowances of feed administered with or without ractopamine. Heterozygote [MSTN A/G (n = 40)] and homozygote wildtype [MSTN G/G (n = 39)] castrate male lambs were individually fed ad li...

The objective of this study was to evaluate the effects of ractopamine (Rac) and Arg fed to pregnant sows from d 25 to 53 of gestation on fetal muscle development as well as the performance and carcass characteristics of the progeny. One hundred sows were divided into 4 treatments including a control diet, the control plus 1% Arg, the control plus 20 mg/kg Rac, and the control diet supplemented...

A meta-analysis of the effect of Topmax (ractopamine HCl) on the performance of hen and tom turkeys when administered the last 14 d of finishing was conducted. Summary data from 18 studies were included. PROC GLIMMIX (SAS Inst.) was used with a model including fixed effects of linear and quadratic Topmax, sex, breed, age and their interactions and a random study effect. Any non-significant (α >...

Previous research indicates that finishing steer ADG and G:F increases linearly with increasing dietary Zn-amino acid complex (ZnAA) supplementation in cattle fed ractopamine hydrochloride (RAC). The objective of this study was to determine the influence of supplemental Zn-amino acid complex on growth performance and carcass characteristics of finishing steers fed RAC for 0, 28, or 42 d prior t...