[Fattening and slaughter values of pigs in relation to their genotype and to the protein source in their feed rations]

The studies were carried out on F1 progeny of multiparous Polish Large White sows and boars of Belgian Landrace, Hampshire x Pietrain hybrid, and Pietrain breed. The control group consisted of purebred Polish Large White pigs. The experimental part of the studies was performed on 120 fatteners divided up to 4 race groups, with 30 heads in each (namely 15 barrows and 15 gilts). Moreover, each group was divided into two following subgroups: the SoS one, which was given feed mixture with extracted soybean meal and the RpS one, which was given feed mixture with extracted rapeseed meal. The fattening started with 23 kg of body weight and was realized up to 100 kg. Twenty fatteners from each group (including 5 barrows and 5 gilts from a subgroup) were subjected to the control slaughter. The fatteners average daily body weight gains, and energy and digestible crude protein conversion per 1 kg of gain were as follows: after Belgain Landrace boars 788 g, 32.3 MJ and 358 g; after Hampshire x Pietrain boars 766 g, 33.6 MJ and 373 g; after Pietrain boars 720 g, 34.4 MJ and 382 g; after control group boars 705 g, 36.3 MJ and 403 g, respectively. It was found that hybrids after boars of evaluated breeds have positively (P < or = 0,01) better carcass meatness, and in a better way use digestible protein and metabolizable energy for production of 1 kg of meat. On that reason the best are hybrids after Belgian Landrace boars, carcasses of which yielded 52.4% of meat and converted 27% less of digestible crude protein and metabolizable energy for 1 kg meat production, than the White Large Polish fatteners. For no examined feature interaction between genotype and protein source in feeding diet was found. The growth rate and utilization of fodder were better for pigs fed on mixture with extracted soybean meal than for the ones fed on mixture with extracted rapeseed meal (P < or = 0.05). The fodders with high protein content did not differentiate meatness traits, whereas digestible crude protein and metabolizable energy conversion for 1 kg meat production in pigs, being given extracted soybean meal in diet, was lower (P < or = 0.05) than in pigs given extracted rapeseed meal.