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THE BASIS FOR PIG HYBRIDIZATION: EVALUATION METHOD FOR THE COMBINING ABILITY OF LINES

Ivan Fyodorovich Gorlov, Marina Ivanovna Slozhenkina, Dmitriy Vladimirovich Nikolaev, Aleхandr Anatolyevich Mosolov, Olga Evgenyevna Krotova, Olga Leonidovna Treteykova, Olga Pavlovna Shahbazova, Aleksandr Aleksandrovich Chernyak

Single commercial cross breeding widely used in animal husbandry does not always guarantee heterosis, since each breed has a fairly wide range of genetic variability. This is what makes the cross breeding different from hybridization. The purpose of these studies was to develop a method for calculating the combination heritability of traits exemplified by specific lines of herd boars of the Large White breed. The research work was based on the results of a long breeding experiment to obtain Large White pigs conducted in breeding farms of the Krasnodar Territory, i.e., Gulkevichsky, Ventsy-Zarya, Caucasus and Industrialny genetic selection centre. The breeding work on these farms was aimed at genetic differentiation of the existing lines according to the Maligonov-Libizov’s method of intrastrain combination. This method has been used in breeding since 1963. Thus, unrelated factory lines have been created within more than 10-15 lines of ancestors. For processing, there were selected only linear boars and sows that had at least 5 lines of the breed the animal was related to. Only linear pigs were investigated. The materials presented have proved that there is no reason to expect a general combining ability (GCA) in terms of traits with a high degree of the hereditary determination. The research has found a high proportion of specific combining ability (SCA) being noted in the reproductive fitness in the range of from 32.78 to 82.90% and in fattening and meat indices from 18.4 to 25.8%. The influence of reciprocal effects was significant in reproductive traits and ranged from 6.16 to 65.2%. The GCA manifestation can be predicted and used in a combining system of structural elements of crossing breeds according to additive effects. The hereditary deposits are apparently consolidated by the additive interaction, which determines the heritability estimate of the selection trait. This indicated the probability of a heterosis effect guaranteed with respect to the reproductive traits between the group genotypes with consolidated heredity. The studies presented are relevant and necessary for development of software in pedigree pig breeding aimed at evaluating the combining ability of the lines. Only then it is possible to quantify and guarantee the heterosis effect during the hybridization of pigs. Key Words: combining ability, crossing variants, GCA and SCA effects, genetic population indices, hybridization.

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