Carcass composition of cull sows

Abstract

Two hundred and four sows were slaughtered in seven weight classes (WCs) from < 99.9-kg to > 225-kg carcass weight in 25-kg increments and 11 fat classes (FCs) from < 9.9-mm to > 55-mm backfat depth in 5-mm increments. Backfat thickness (probe fat) and loin muscle depth (probe lean) 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 loin were then separated into trimmed commercial cuts to determine commercial yield and then defatted and deboned to determine retail yield, lean yield, fat yield and bone yield. Dressing percentage was lowest for 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 decreased, while the percentage of the loin and belly increased as WC and FC increased. FC produced significant effect on the percentage of the shoulder, loin and belly, whereas WC had significant influence only on the proportion of the shoulder and belly. There was a significant WC × FC interaction (P < 0.002) upon the percentage of the belly yield. The percentages of commercial yield, retail yield, lean yield and bone yield were reduced, and that of fat yield increased as WC and FC increased, but WC only produced significant effects on the percentage of lean and bone yield. Carcass composition of cull sows was better correlated to backfat thickness than carcass weight, since the increase in carcass weight as live weight increased was primarily fat. Key words: Carcass composition, sows, lean yield