The influence of terminal sire genotype, sex, slaughter weight, feeding regime and slaughter-house on growth performance and carcass and meat quality in pigs and on the organoleptic properties of fresh pork

A total of 897 pigs were used in a study to investigate the relative effects of terminal slue genotype (lines A v. B v. C), sex (castrate v. gift), slaughter weight (80 v. 100 v. 120 kg), feeding regimen lad libitum v. restricted, 0.82 ad libitum intake) and slaughter-house (H1 v. H2 v. H3) on growth performance, cal cass and meat quality characteristics and the eating quality of fresh pig meat. Sire line A was a pure Duroc population, and B and C were European-type experimental lines where C contained Pietrain and B did not. In fetal, 26 sires from line A, 42 sires from line B, and 21 sires from line C were mated to females from the same crossbred dam line and progeny were reared under standard conditions to slaughter. Following slaughter and carcass evaluation, samples of longissimus dorsi were investigated for a range of meat quality and organoleptic characteristics. Line A produced fatter carcasses (C fat depths = 15.6 v. 14.0 v. 14.0 mm for lines A, B, and C, respectively, average s.e. 0.39) with higher killing-out proportions (g/kg) (790 v. 779 v. 786 respectively, average s.e. 1.4) and higher visible marbling, less tissue separation, firmer backfat, and juicier (3.81 v. 3.67 v. 3.71 respectively, average s.e. 0.044: on a scale 1 (extremely dry) to 8 (extremely juicy)) and more acceptable meat (4.54 v. 4.37 v. 4.41 respectively average s.e. 0.037: on a scale 1 (dislike extremely) to 8 (like extremely)) with a lower shear force (5.35 v. 5.78 v. 5.67 kg respectively, average s.e. 0.078) than lines B and C which were similar in most respects. Increases in slaughter weight were associated with a reduction in growth rate (785 v. 769 v. 725 g/day for 80, 100 and 120 kg slaughter weight respectively, average s.e. 8.5), increases in backfat (C fat = 13.3 v. 14.1 v. 16.3 mm respectively, average s.e. 0.34) and longissimus muscle area (34.6 v. 40.7 v. 44.6 cm(2) respectively, average s.e. 0.59) and a deterioration in tenderness (4.72 v. 4.40 v. 3.95 respectively, average s.e. 0.062: on a scale 1 (extremely tough) to 8 (extremely tender) and overall acceptability (4.65 v. 4.44 v. 4.25 respectively, average s.e. 0.045) and an increase in shear force (5.37 v. 5.58 v. 5.87 kg respectively, average s.e. 0.085). Slaughter-house had a significant impact on pork odour scores but not on other organoleptic properties. Pigs reared under ad libitum feeding grew faster (840 v. 678 g/day respectively, average s.e. 3.7), were fatter (C fat = 15.8 v. 13.2 mm respectively, s.e. 0.28), had lower carcass yields (780 v. 790 g/kg respectively, average s.e. 1) and produced more tender, juicier meat than those reared under restricted feeding. Differences between castrated males and gilts in growth and cal cass trait were in line with other studies and there were no significant differences between the sexes for eating quality. There were relatively few significant interactions (P < 0.05) for eating quality traits and most of these involved slaughter-house and were for pork odour intensity, which are of limited practical significance. This suggests that the effects of sire genotype, slaughter weight and feeding regimen on eating quality identified in this study are likely to be additive.