Genetic Evaluation of some Carcass Characteristics Assessed by <i>in vivo</i> Real Time Ultrasonography in Baluchi Sheep

Abstract

In order to evaluate carcass characteristics of a nucleus flock of Baluchi sheep, <em>in vivo</em> ultrasound technique was used to measure backfat thickness (UBFT) and longissimus dorsi muscle area (ULMA) and also to estimate genetic parameters for these ultrasonic traits and live weights in different ages. The data were collected from 576 animals during 2011. (Co)variance components were estimated by univariate and bivariate animal models using restricted maximum likelihood and Asreml software. Females had higher UBFT and ULMA than males. Estimates of direct heritabilities were 0.32, 0.23, 0.27, 0.02, 0.12, 0.22 and 0.18 for UBFT, ULMA, birth weight (BW0), weaning weight (BW3), 6 month weight (BW6), 9 month weight (BW9) and yearling weight (BW12), respectively. There were positive and high genetic (0.68±0.15) and phenotypic (0.62±0.03) correlations between UBFT and ULMA. The genetic correlations among ultrasonic and pre 6 month weights were positive and low except for BW0 and ULMA (0.39±0.28). Contrarily, moderate to high positive genetic correlations between ultrasonic traits and weaning and post-weaning weights were found (0.33 to 0.61). Phenotypic correlations between ultrasonic and growth traits were positive and ranged from 0.09 to 0.37. High positive genetic correlation between UBFT and ULMA suggests that selection for larger muscle mass result in higher fat carcasses.