Effect of genetic type and dietary protein level on growth, carcass and ham traits of heavy pigs

This study, supported by AGER (grant 2011-0280), investigated the effects of genetic type (GT) and dietary crude protein (CP) content on variation of growth performance, carcass and ham traits in finishing heavy pigs. Genetic types, selected according to their diffusion in commercial farms, involved Duroc × Large White ANAS (A), C21 Goland (G), Tempo × Topigs 40 (T) and DanBred (D) lines. A total of 184 pigs (gilts and barrows) were raised in 2 subsequent trials from 90 to 165 kg BW and were fed, under restricted feeding, conventional 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 housed in 8 pens equipped with feeding stations recording individual feed intake. Pigs were slaughtered at 9 months of age (average BW: 165±12.4 kg) and weights of carcass and typical cuts and backfat thickness were recorded for all carcasses. After 24-h chilling, hams were trimmed, weighed, scored and measured for several quality traits. A sample of trimmed fat was taken from hams to assess iodine number and linoleic acid content. All hams were cured according to the San Daniele procedure. Weight losses during curing and number of hams discarded were recorded. All traits were analysed by ANOVA. Genetic type affected variation of most growth and carcass traits: D pigs showed the highest ADG and gain to feed ratio and provided carcasses with the highest and lowest incidence of lean and fat cuts, respectively. Ham quality traits were mostly affected by GT, 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 PDO production in D and T was twice as high as in A and G. Effects of diets were less important, but low dietary CP tended to increase ham subcutaneous fat covering and quality. No interaction effect between genetic type and diet was detected.