Khramkova O. Economic and biological features, adaptive properties of Irish origin pigs and their use with different breeding methods

The dissertation is devoted to the assessment of economic and biological features, adaptive properties of Irish origin pigs and their use with different breeding methods to obtain commercial hybrids in Ukraine. In the conditions of industrial farming of Ukrainian steppe, it is established that the combination (♀Y×♂L) of Irish origin is the best maternal form for hybridization when sows are crossed with boars of the "MaxGrow" line of Irish selection. It is proved that the fattening indicators of the final hybrids are better with the use of F1 (♀Lі×♂Yі) sows as the maternal form in crossing with boars of synthetic lines of foreign origin compared to crossing the same boars with F1 (♀Yі×♂Lі) sows. It is determined that sows of native selection in comparison with foreign ones, both during pure-breeding and crossing, differ in the coefficient of adaptation better by 0.12-0.24 points and the heat resistance index better by 0.4-5.4 points. It is found that stress-sensitive piglets were absent among the offspring of native animals, while they were found in the amount of 6% among purebred piglets of Irish origin. All local piglets of different genetic combinations had more stress-sensitive individuals than purebred ones. The most sensitive to stress were animals with high nominal blood relationship of Danish Landrace breed (18-33%). It is found that pigs of foreign origin had greater weight loss during transportation compared to native animals. The increase of pre-slaughter weight of pigs to 120 kg led to a decrease of weight loss during transportation by 0.2-0.3%. The impact of the breed crossing on weight loss during transportation was 33.1%, while the weight loss was 7.36%. It is found that animals of foreign genotypes exceeded their domestic peers in meat yield by 2.7-4.2%, while the quality of meat was better in native animals. In animals of all experimental genotypes, with an increase of pre-slaughter weight from 100 to 120 kg, the thickness of the back fat, the mass of the ham, and the area of the "ribeye muscle" increased significantly. The meat yield, with an increase of pre-slaughter weight by 20 kg, decreased less in the carcasses of animals of foreign selection compared to the carcasses of animals of native selection. It is shown that the impact of breed crossing on the meat content in the carcass was about 27.3%, while the pre-slaughter live weight had an impact on this figure about 6.0%. It is proved that the meat of animals of all experimental groups had a level of acidity and moisture retention within the norm, according to the European category NOR (normal). Meat of animals of native selection, with both slaughter weight of 100 and 120 kg, has the best quality indicators. It is found that the meat of animals obtained from intensive commercial genotypes of foreign selection has a higher protein content and lower fat and ash content compared to the meat of native pigs. It is proved that the most economically advantageous is the fattening of pigs obtained from a combination of "MaxGrow" boars with Li × Yi and Yi × Li sows up to a live weight of 120 kg, where the level of profitability is 63%.