Date of this Version
Economic selection indices were derived for terminal sire sheep breeds or strains, using physical and financial results from New Zealand export lamb-producing flocks. The aggregate breeding value comprised carcass lean weight and carcass total fat weight. Index measurements were live weight, ultrasonic fat depth and ultrasonic muscle depth. Economic values of lean weight and fat weight were estimated to be NZ $5. 07 and NZ $-3.72 per kg, respectively. The s.d. of the aggregate breeding value was NZ $3.20 and the correlation between the full index and the aggregate breeding value was 0.23. The expected economic response to selection on live weight alone was only 29 % of that expected from selection on the full index .