CARCASS COMPOSITION OF CULL SOWS

Two hundred and four sows were slaughtered in seven weight classes (WC s) from < 99.9-kg to > 225-kg carcass weight in 25-kg increments and 1 1 fat classes (FCs) from < 9.9-mm to > 55-mm backfat depth in 5-mm inc rements. Backfat thickness (probe fat) and loin muscle depth (probe le an) were measured on the left side of the carcass between 3rd and 4th last rib 7 cm from midline by electronic probe. The left side was cut into four primals: shoulder, ham, loin and belly. Shoulder, ham and lo in were then separated into trimmed commercial cuts to determine comme rcial yield and then defatted and deboned to determine retail yield, l ean yield, fat yield and bone yield. Dressing percentage was lowest fo r those sows in fat class 1 (77.4%) and highest for those in fat class 11 (83.7%). Percentage of shoulder and ham in the carcass side decrea sed, while the percentage of the loin and belly increased as WC and FC increased. FC produced significant effect on the percentage of the sh oulder, loin and belly, whereas WC had significant influence only on t he proportion of the shoulder and belly . There was a significant WC x FC interaction (P < 0.002) upon the percentage of the belly yield. Th e percentages of commercial yield, retail yield, lean yield and bone y ield were reduced, and that of fat yield increased as WC and FC increa sed, but WC only produced significant effects on the percentage of lea n and bone yield. Carcass composition of cull sows was better correlat ed to backfat thickness than carcass weight, since the increase in car cass weight as live weight increased was primarily fat.