Ladyka , V., Sklyarenko , Y., Pavlenko , Y. and Malikova , A. 2020. Comparative evaluation of dairy productivity of cows of ukrainian brown milk breed of different genotypes by β-casein. Bulletin of Sumy National Agrarian University. The series: Livestock. 3 (42) (Nov. 2020), 3-7. DOI:https://doi.org/10.32845/bsnau.lvst.2020.3.1.