Abstract. Title of the paper: Effect of sire breeds in commercial pig crosses on growth, carcass composition, meat and fat quality
200 weaners from a large field trial in Niedersachsen to test different German and foreign sire breeds for their ability to improve the quality of market products were put at an individual feeding trial at the FAL-Nutrition Institute in Braunschweig. It was the aim of this feeding trial to compare the effects of different fat additions to the diet, sire breeds, sexes and slaughter weights upon growth and usual carcass traits but also upon several additional meat and fat quality traits. The trial was carried out in two blocks with 96 pigs each with the sire breeds Pietrain of the two MHS-genotypes PP (stress susceptible) and NN (stress resistant), Duroc and Hamsphire*Duroc (both NN) as preferrably used in Denmark. As control in both blocks the BHZP-standard boar 65 (PI*HA(NN)) was used. Here only the sire breed effects will be reported. In daily gain and energy conversion only DU-progeny differed significantly from the control (+33g, −1.32 MJ/kg). The tissue dissection showed that PI(PP)-, DU- and HA*DU-progeny had 0.8–1.0% higher bone and respectively lower residual components (lean, fat, tissue). In carcass measurements PI(PP) progeny were the leanest followed by PI(NN), and DU progeny had the smallest loin eye areas and carcass lean contents. This affected the carcass cuts such that PI(PP) progeny had a 1.2 % (= 1.08 kg) higher sum of primal cuts and DU progeny with –0,8% (−400g) below the control were the poorest. In meat quality traits only the heterozygote stress susceptible PI(PP) progeny showed highly significant poorer values than all other crosses, which differed little from each other. This was confirmed by drip losses 2 and 4 days post mortem, which were 1.3–1.6% higher than the control whereas DU progeny were the best with –0.6%. Chemical analysis of a loin sample produced for both Danish sire breeds significantly higher intramuscular fat (+0.36–0.38%) and for PI(PP) progeny with –0.32% the lowest values, but the overall mean reached only 1.3% intramuscular fat. The protein and glycogen contents of loin revieled the expected large deviations of Hamsphire progeny due to the dominant RN- gene (−0.8–1 % protein, +10–14 μmol/g glycogen). All HA-free crossbreds did not differ much. The fatty acid composition of backfat and intramuscular fat showed much smaller differences between sire breeds than between fat supplements to the ration, but Danish sire breeds transmitted higher contents of polyunsaturated and Omega 3 fatty acids than the other sire breeds. Finally, for animals of the second trial also a sensoric test of loin samples was performed at the Federal Meat Research Institute. There subjective scores for tenderness and juiciness as well as grill losses showed significant sire breed differences. But contrary to expectation both Danish sire breeds produced inferior quality in all three traits to PI*HA(NN) control sire groups.