A terminal-sire index for selecting rams
A terminal-sire index for selecting rams was developed. It combines genetic evaluations for growth traits and carcass characteristics measured ultrasonically on live animals into a single criterion. Weightings for component traits are averages from the indexes of four slightly different breeding goals, determined using economic values and parameters from the literature. The weightings for breeding values of component traits are -1.45 for birth weight, +1.86 for weight at 50 d of age, +2.27 for gain from 50 to 100 d, -0.51 for ultrasonic fat depth, and +1.36 for ultrasonic loin muscle depth, in phenotypic standard deviation units. Selection that is based on the index will increase growth while simultaneously decreasing fat and increasing muscle. Key words: Breeding strategies, carcass characteristics, growth, selection, sheep