Proceedings of the New Zealand Society of Animal Production.
1991, 51: 405-410
Proceedings of the New Zealand Society of Animal Production.
1991, 51: 405-410
The equation to predict lean weight was: 0.316+(0.547 x HCW) - (0.070 x GR), Rū= 0.91. The equation to predict fat weight was: -1.15+(0.223 x HCW) + (0.132 x GR), Rū=0.88.
A computer simulation program was used to generate data for 100 000 carcasses with log-normal distributions for HCW and GR, and with means (standard deviation) of 14.3 kg (2.4) for HCW and 8.03 mm (3.59) for Gr. Lean and fat weights were calculated from the prediction equations obtained from the dissection data. Relative economic values (REV's) of lean and fat were obtained from a multiple regression of carcass value on lean weight and fat weight. Carcass value was taken as HCW multiplied by a mean net schedule price/kg for that export grade of carcass from a national summary. The values were calculated using average prices from each marketing year from 1985/86 to 1989/90. Grades were determined from HCW and GR of each carcass.
The REV of a kg of lean, when a kg of fat was set to -1, ranged from 0.92 to 1.69. There was no obvious time trend in the REV's obtained. The correlation between weight of lean and carcass value ranged from 0.31 to 0.69. The correlation between HCW and carcass value ranged from 0.21 to 0.63.
The results will be used to derive breeding objectives and determine selection strategies for improvement of sheep meat production.
Keywords: NZSAPAB; Carcass; sheep; simulation; lean; fat; relative economic value
