Reproductive characteristics of pigs of Irish selection and manifestation of different forms of heterosis by different methods of breeding in modern conditions of industrial pork production
Authors: Kremez M. I. , Povod M. G. , Mykhalko O. G. , Susol R. L. , Trybrat R. O. , Onishenko L. V. , Kravchenko O. O. , Verbelchuk T. V. , Sherbyna O. V. 
Published: June 2022

The manifestation of different forms of heterosis and its effect on the reproductive capacity of pigs of modern genotypes of Irish selection by different methods of breeding in domestic industrial production on breeding and commercial breeders LLC “SPE “Globinsky pig farm.” To compare the reproductive capacity of animals in purebred breeding, crossbreeding, and hybridization and their dependence on the manifestation of various forms of heterosis of potential and actual multiplicity, high fertility, and nest weight of piglets at birth and weaning, the number of weaned piglets per nest and their safety. A comprehensive assessment of the reproductive qualities of sows was determined using an evaluation index with a limited number of traits, and the selection index of reproductive qualities of sows was determined according to the proposed method. Heterosis indices were determined by V. T. Gorin and I. M. Nikitchenko and modified by O. M. Tserenyuk. Biometric processing of the obtained data was performed by using variation statistics using a personal computer software Microsoft Excel. It was found that the indicators of reproductive traits of sows of all experimental groups and combinations studied were characterized by high reproductive performance, except for purebred sows of the synthetic line Max Gro. Sows of large white and landrace breeds in their direct and reverse cross outperformed their purebred counterparts in birth by 2.8 % in terms of fertility, 2.2 % in terms of nest weight of piglets at birth, and 1.7 % in terms of high fertility. They weighed 4.1 % more piglets, weighed 1.3 % more weight, and 4.6 % the weight of the nest, while the preservation of piglets before weaning was not significantly different between animals of these groups. According to a comprehensive assessment of reproductive indicators, they were 2.8–3.3 % higher when crossing parent breeds than their purebred breeding. At the final stage of hybridization, the advantages of hybrid nests over purebreds (maternal form) during farrowing were established – by potential and actual fertility by 3.9 % and 2.2 %, respectively, by nest weight of piglets at birth and high fertility by 6.3%, and 6.8 %. When weaned, their preferences were – for the safety of piglets – 1.7–2.0 %, for the number of piglets, the weight of their nest, and the weight of one head when weaned by 5.7–6.5 % and 8.5 % and 4.2 %, respectively. According to a comprehensive assessment of sows using the SIVYAS index and the index of reproductive qualities of sows with a limited number of traits, an advantage of 3.9 % and 3.3 % of hybrid nests over purebreds was established. At the same time, sows in hybridization outperformed purebred analogs of the synthetic line Max Gro at the time of farrowing by potential and actual multiplicity by 34.2 % and 59.1 %, nest weight by nest weight of piglets at birth by 27.8 % but had a lower by 25.8, 8.0 % high fertility. At the time of weaning in hybrid nests, there were 54.1 % more piglets, 11.8 % higher live weight of 1 head, and 8.5 % live weight of nests of piglets, according to a comprehensive assessment of sows for SIVYAS and IVYa by 25.9 and 31.8 %, respectively, but they have a 4.6 % worse safety of piglets compared to analogs of the synthetic line Max Gro. There was a more pronounced effect of heterosis on such features as the number of piglets at weaning, live weight of the nest at weaning, SIVYAS and evaluation index, and moderate level of heterosis effect on the average weight of 1 head at weaning at 28 days and average daily gain of young for suckling period. Under the conditions of two-breed crossbreeding, an increase in reproductive indicators was found to a greater extent due to the manifestation of hypothetical and general forms of heterosis, while in hybridization, in most cases, specific and authentic heterosis was manifested.