Estimates of genetic parameters for different body weights and muscle and fat depths of Karayaka lambs

Abstract

In the current paper the direct additive and maternal genetic effects on birth, weaning (at 90 days of age), and scanning (at 20 weeks of age) weights and muscle and fat depths of the ribeye area in Karayaka lambs were investigated. Analyses were carried out by the restricted maximum likelihood approach, fitting 6 animal models with various combinations of direct and maternal effects. The best model was chosen after testing for improvement in the log-likelihood values. Direct heritability (h(d)(2)) for all traits decreased when maternal genetic effects were included in the models. The maternal heritability (h(m)(2)) ranged from 0.15 to 0.22 for birth weight, from 0.04 to 0.14 for weaning weight, and from 0.08 to 0.16 for scanning weight. The effects of h(m)(2) on muscle depth and fat depth of the ribeye area were not considered due to their insignificance. The permanent environmental effect of the dam was significant for birth, weaning, and scanning weights. Moderate negative genetic correlations (r(am)) between the direct and maternal genetic effects were observed, which were significant for birth (-0.179 and -0.221), weaning (-0.310 and -0.415), and scanning (-0.116 and -0.141) weights. As a result, h(d)(2) and h(m)(2) can be used as selection criteria for birth, weaning, and scanning weights in Karayaka lambs.