Growth performance, and carcass and raw ham quality of crossbred heavy pigs from four genetic groups fed low protein diets for dry-cured ham production

This study investigated growth performance, and carcass and raw ham quality of pigs from4 genetic groups (GG), ANAS (A), DanBred (D), Goland (G) and Topig (T), fed conventional(CONV) or low-protein (LP) diets. In each of 3 trials, 96 pigs were housed in 8 pens in groupsof 12 on the basis of their GG, sex (gilts and barrows), and BW. Each pen was assigned a CONVor LP diet. The CONV diets in early (89–120 kg BW) and late (121–165 kg BW) finishing con-tained 13.1 and 13.2 MJ/kg of ME, 147 and 132 g CP/kg, and 6.0 and 4.4 g/kg of standardizedileal digestible (SID) lysine, respectively. The LP diets in early and late finishing containedonly 119 and 103 g/kg of CP, and 4.8 and 3.5 g/kg of SID lysine, respectively. Restricted feedallowance was increased on a weekly basis from 2.3 to 3.2 kg/d during the experiment.Automated feeding stations measured individual feed intake, and pigs were weighed at3-weeks intervals until slaughter. Hot carcass was weighed and dissected into lean andfat primal cuts. After 24 h of chilling, hams were dressed, weighed, and scored for round-ness (0 = low to 4 = high), fat cover thickness (−4 = thin to 4 = thick), marbling (0 = absent to4 = evident), lean color (−4 = pale to 4 = dark), bicolor and veining (0 = absent to 4 = evident).In addition, ham backfat thickness was measured with a ruler. Dietary CP reduction did notinfluence final BW (166 kg), daily gain (0.67 kg/d), carcass weight (136 kg) or yield (0.82),but reduced feed efficiency by 5.2% (P < 0.001). Irrespective of GG, the reduction in proteinsupply increased fat cover depth (P < 0.001) and marbling (P = 0.009) of hams, but did notinfluence other traits. Compared to A, hams from D were heavier (+6.4%; P < 0.001), andhad a thinner cover fat (19.4 vs 24.8 mm, P = 0.001), a greater marbling score (2.05 vs 1.44points; P < 0.001) and a paler lean color (−0.61 vs 0.34 points; P < 0.001). Ham quality of A, Gand T was comparable, but the marbling score of T was higher and similar to that of D. The use of low-protein diets would reduce the environmental impact of heavy pig productionwith some improvement in ham quality (> subcutaneous fat depth), although increasedmarbling is expected. They should preferably be used with GGs that have low marblingscores under conventional conditions.