Estimation of the relationship between central performance test and progeny performance in Rambouillet sheep

Abstract

Twenty-five Rambouillet rams were chosen from central test over a three-year period. Rams were single-sire mated to Rambouillet ewes. Progeny were weaned at an average of 129 d and given ad libitum access to a high energy finishing diet postweaning. Progeny traits of interest were weaning weight, preweaning average daily gain (ADG), postweaning ADG, final weight, final weight per day of age (WDA), hot carcass weight (HCW), fat thickness (FT), longissimus muscle area (LMA), and carcass length. Progeny performance was regressed on sire's central test performance (ADG, final weight, ultrasound FT, and ultrasound LMA). Paternal half-sib and parent-offspring heritability estimates for the traits of interest were also calculated. Regression coefficients were only significantly different from zero for progeny postweaning ADG and final WDA when regressed on sire's ADG and final weight, and progeny FT when regressed on sire's ultrasound FT. When regressed on sire's average daily gain, the coefficients for postweaning ADG and WDA were 0.18 ± 0.10 and 0.12 ± 0.05, respectively. The coefficients, when regressed on sire's final weight, were 0.0011 ± 0.00044 for ADG and 0.0004 ± 0.0002 for final WDA. Paternal half-sib heritability estimates ranged from 0.21 for carcass length to 0.84 for postweaning average daily gain. Parent-offspring heritability estimates were 0.36 for postweaning ADG, 0.12 for final weight, 0.34 for FT, and 0.12 for LMA. The estimated correlation coefficient between feed consumption and sire's ADG was 0.35 and was different from zero (P < 0.01). Regression coefficients for feed consumption on sire's ADG and final weight were 2.95 ± 1.04 and 0.012 ± 0.005, respectively. These results suggest that central performance test was a better indicator of progeny performance on traits measured postweaning on an environment similar to that of the central test.