Effects of backfat thickness and carcass weight on the chemical composition and quality of the meat from culled sows

Abstract

A total of 204 sows, ranging in carcass weight from 73 to 279 kg and backfat thickness from 6.5 to 67.6 mm, were slaughtered and separated into four WC from < 119.9 kg to > 200 kg carcass weight in 40 kg increments and four FC from < 13.9 mm to > 32 mm backfat depth (probe fat) in 9-mm increments. Depth of fat (probe fat) and lean (probe lean) was measured between the 3rd and 4th last ribs 7 cm from the midline using an electronic probe. The left side was cut into four primals: shoulder, loin, ham and belly. All primals, except belly, were separated into lean, fat and bone. This dissected side lean, for 90 sows across WC and FC, was analyzed for protein, lipid, water and ash. Colour of LT and BF and drip loss of the loin muscle were also determined. As WC and FC increased, the proportion of lipid increased by 57.1% (P = 0.531) and 258.5% (P = 0.001), respectively. Water content of dissected lean decreased by 5.1% (P = 0.782) and 6.3% (P = 0.001) as WC and FC increased, respectively. Carcass weight and probe fat were significantly correlated with lipid percentage (r = 0.51 and 0.60, respectively) and chemical water percentage (r = −0.50 and −0.55, respectively) in side lean. As WC increased, both LT and BF became significantly darker. As FC increased, BF muscle became more yellow (P = 0.058). Drip loss was significantly associated with L* (r = 0.61) and b* (r = 0.63) values. The changes in the chemical composition of the separable lean were primarily a function of carcass fatness, whereas the brightness of the LT and BF were mainly influenced by WC. Key words: Sows, chemical composition, protein, meat colour, backfat depth