Optimal Slaughter Weights and Carcass Value for Three Genotypes of Hogs1

Differences in optimal slaughter weights were examined for barrows and gilts for three genotypes marketed under two pricing systems. Ninety-six barrows and 95 gilts were used. The first genotype (G1) averaged 44.4 and 48.8% standardized lean (10% fat) for barrows and gilts, respectively. The second genotype (G2) was 53.1 and 54.2% lean, respectively, and the third (G3) measured 47.1 and 52.7%, respectively, at an average slaughter weight of 120 kg. Carcass value was determined using a component (CO) pricing system with separate payments for lean, fat, and by-product, a live weight pricing system (LW), and backfat measurements from a Destron® probe (PR). Growth functions that define the relationships between live weight, time, and feed intake were estimated. Allometric functions were used to estimate the relationship between lean, fat, and live weight. Optimal slaughter weights were estimated by maximizing average daily profit per hog under the CO, PR, and LW pricing systems using 1991 prices and production costs. Optimal slaughter weights were lighter for the genotypes with more carcass lean. The range of differences in carcass value was higher using CO as compared to PR and LW. These carcass value differences were greater for G2, suggesting that LW does not accurately reflect the actual carcass value. The PR system underestimated lean in the G1 and G3 gilts, and G2 barrows and gilts. The differences in optimal slaughter weights across sex and genotype can be attributed to the differences in the lean growth curves and feed efficiency. To capture these differences in carcass value, producers should market genetically leaner hogs based on carcass merit.