Effect of genetic type and dietary crude protein level on carcass and ham traits of finishing heavy pigs

This trial was supported by AGER, grant n. 2011-0280, and aimed to study the effect of genetic type and dietary crude protein (CP) level on carcass and ham traits of heavy pigs. Genetic types were selected according to their diffusion in commercial herds and involved Duroc x Large White ANAS (A), C21 Goland (G), Tempo x Topigs 40 (T) and DanBred (D) lines. A total of 184 pigs (gilts and barrows) progeny of at least 4 sires per line were raised in 2 subsequent trials from 90 to 165 kg BW and were fed convention- al or low-protein diets providing on average 140 g CP and 6.45 g lysine/kg or 106 g CP and 4.85 g lysine/kg of diet, respectively. Pigs were slaughtered at 9 months of age (average BW: 165±12.4) in the same abattoir and on a single day per trial. Hot carcass weight, backfat thickness and typical cuts weight were recorded for all carcasses. After a 24-h chilling period, hams were trimmed and then weighed and evaluated for shape, fat coverage and marbling. Fat covering depth was recorded through ruler and ultrasound, and a sample of trimmed fat was taken from all hams to assess iodine number and linoleic acid content. All hams were cured according to the San Daniele procedure, and weight losses during ageing and number of hams discarded were recorded. All traits were analyzed through ANOVA. Genetic type highly affect- ed most carcass traits, and D pigs provided carcasses with the highest incidence of lean and the lowest incidence of fat cuts. Also ham quality traits were mostly affected by genetic types, and hams from A and G had higher fat covering thickness, lower iodine number and a better overall evaluation than other genetic types. Incidence of hams not suitable for DPO production was nearly double in D and T with respect to A and G. Effects of diets were less important, but lowering dietary CP tended to improve ham subcutaneous fat covering and quality. No interaction effect between genetic type and diet was detected.