Effects of growth rate, sex and slaughter weight on fat characteristics of pork bellies.

A total of 119 Duroc×(Landrace×Yorkshire) commercial pigs were used to investigate the effect of growth rate (fast vs slow), sex (barrows vs gilts) and slaughter liveweight (107, 115 and 125kg) on the fat characteristics of bellies. Backfat thickness increased with weight (P<0.01). Fat firmness score was only affected by sex (P<0.05), with gilts showing softer bellies than barrows. Fat from gilts and slow growing pigs showed a lower proportion of saturated fatty acids (SFA; P<0.001 and P<0.01, respectively), a higher proportion of linoleic fatty acid (C18:2 n-6; P<0.01), a higher proportion of total polyunsaturated fatty acids (PUFA; P<0.001 and P<0.01, respectively), and an increased iodine value (P<0.001). Consequently, the fat from these bellies had higher PUFA:SFA ratios (P<0.001) and n-6:n-3 ratios (P<0.01 and P<0.001, respectively) than that from the bellies of barrows and fast growing pigs. The belly fat from barrows and fast growing pigs had higher stearic fatty acid (C18:0; P<0.01) and SFA proportions (P<0.001 and P<0.01, respectively) than that from gilts and slow growing pigs. The belly fat from gilts and slow growing pigs would better meet the health requirements of consumers, but it is more prone to rancidity during storage leading to a potentially reduced bacon shelf-life.