Shvachka , R. and Povod , N. 2020. Influence of the factors of the variant of combination of breeds and duration of the lactation period on reproductive qualities of sows. Bulletin of Sumy National Agrarian University. The series: Livestock. 1 (40) (Feb. 2020), 94-102. DOI:https://doi.org/10.32845/bsnau.lvst.2020.1.14.