MANIFESTATION OF THE HETEROSIS EFFECT IN SOWS UNDER THE DIFFERENT BREED COMBINATIONS

The aim of the research was to assess the manifestation of the heterosis effect in sows under the different breed combinations. The research was conducted on the basis of the pig farm of the private enterprise "Skrypnyk V.O." in Lozova district of Kharkiv region. Two control groups (the Poltava Meat and Welsh sows) were formed for insemination with boars of the same breeds in purebred breeding (groups I and II, respectively). Two subsequent groups were formed for reciprocal crossing of Welsh and the Poltava Meat breeds (groups III and IV, respectively). Two experimental groups were also formed by direct combinations of Welsh and the Poltava Meat with boars of the Large White breed (groups V and VI, respectively). The main indexes of reproductive ability of sows were taken into account, on the basis of which the level of manifestation of the heterosis effect was calculated. The highest values of the manifestation of the heterosis effect (general type) in terms of the number of piglets at birth were observed for the combination of the Poltava Meat sows with boars of the Large White and Welsh breeds. In terms of the number of live piglets, the highest values of the manifestation of the general heterosis effect were obtained for the combinations of the Poltava Meat sows with boars of the Large White (11.04%) and the Poltava Meat sows with boars of the Welsh breed (9.82%). In terms of the specific and hypothetical types of manifestation of the heterosis effect, in all cases there was an advantage for the direct combination. Regarding the level of manifestation of the total manifestation of the heterosis effect according to different indexes of reproductive ability of sows for the combination of Welsh and the Poltava Meat breeds, higher values were obtained for the number of piglets at birth (both total and live) and the weight of the litter at weaning. When assessing the reciprocal effect, positive values were obtained for all evaluated indexes, which indicates the presence of a parental effect in reciprocal combinations of Welsh and the Poltava Meat pigs. The assessment of the degree of phenotypic dominance indicates the obtained different types of dominance for different indexes and combinations, which confirms the complex mechanisms of formation of the heterosis effect.