GENETIC AND PHENOTYPIC PARAMETERS OF CARCASS TRAITS IN RAM LAMBS REARED ARTIFICIALLY IN A CONTROLLED ENVIRONMENT

Abstract

Genetic and phenotypic relationships among carcass traits were calculated for 654 ram lambs from 210 sires of three synthetic strains developed at the Animal Research Centre. Lambs were housed indoors in a controlled environment on expanded metal floors and reared artificially with milk replacer and solid diets. Paternal half-sib estimates of heritability at 36-kg body weight and 116 of age were moderate to high ranging from 0.38 to 0.67 for shoulder and leg (trimmed and lean), total trimmed retail cuts, total lean, chilled carcass weight and lean weight per day (P < 0.01). Estimates of phenotypic and genetic correlations between the above traits showed a significantly favorable relationship indicating their usefulness as criteria in selection for meatiness. Heritability estimates for front, back and total in rough retail cuts, trimmed loin cuts, lean in rack and loin, kidney fat weight and dressing percentage ranged from −0.19 to 0.27 (P > 0.05). Estimates involving loin, rack, front, back, total retail cuts, kidney fat wt, dressing percentage and chilled carcass weight per day showed lower and nonsignificant relationships with total trimmed retail cuts or total lean. Key words: Sheep, heritability, genetic and phenotypic correlations, lamb carcass traits