FATTENING QUALITIES OF PIGS OF VARIOUS BREEDING DIRECTIONS IN PUREBRED BREEDING, CROSSING AND HYBRIDIZATION IN THE CONDITIONS OF MODERN PORK PRODUCTION

In order to determine the influence of breed and breeding methods on the productive characteristics of pigs in the process of rearing and fattening, seven experimental groups were formed with animals of different genotypes and breeding directions. Three methods of pig breeding were used in the experiment: Pure breeding (intra–linear), crossbreeding between breeds and breed–linear hybridisation. It was found that the highest live weight gains were achieved by hybridisation with the terminal parental line PIC–337, while purebred breeding with specialised parental lines showed limited efficiency under industrial conditions. A comparison between large white pigs and landraces shows that the landrace has a slightly better growth potential, but the increase in live weight remains moderate. It has been proven that piglets of the PIC–337 endline, which were selected for increased growth energy, are clearly superior to the analogues of the dam breeds in all important growth indicators such as average daily growth during the suckling period and during rearing, as well as total weight at the end of rearing; they consumed more feed during rearing, and converted it more efficiently into live weight gain. At the same time, the hybrids are superior to the indigenous animals in breed–linear hybridisation for all indicators of growth intensity, especially during the rearing phase. The advantage of the hybrids over the local forms in the range of 2–13% is due to the influence of the inheritance of the terminal boar of the PIC–337 line. It was found that animals with the genotype (¼L×¼LW)½PIC–337) were more productive than similar hybrids with (¼LW×¼L)½PIC–337, suggesting that the use of landrace sows as the dam line is appropriate in the creation of hybrids with maximum realisation of the heterotic effect. Thus, the use of crossbreeding and three–line hybridisation can significantly improve piglet productivity both during the suckling period and during rearing. The hybrid animals showed the best results, confirming the effectiveness of heterosis, and the use of landrace sows as the dam line provides an additional improvement in the growth indicators of the offspring. It was found that an intermediate type of inheritance characterised hybrids (¼LW× ¼ L)½PIC–337 with 9–13% lower productivity than purebred animals PIC–337, but with better conservation. Instead, the hybrids (¼L× ¼ LW)½PIC–337) showed marked heterosis, especially in terms of growth rate, absolute growth, and conservation. It was found that the animals of the PIC–337 parental line had significant advantages in fattening in terms of growth rate, reduction in fattening time and increased feed conversion efficiency compared to the parental breeds, making them promising for commercial pork production with high animal turnover rates. Hybrids involving the PIC–337 parent line are characterised by high preservation and close to the indicators of the pure line for feed conversion, but had slightly lower growth rates and feed efficiency. These results indicate an intermediate form of inheritance of these traits, and, considering the significantly higher number of piglets in the nests of hybrid pigs, the further use of hybrids in intensive pig breeding systems is feasible, taking into account their genetic characteristics.