В настоящей работе проведено комплексное исследование морфофункциональных особенностей молочной железы коров черно-пестрой и айрширской пород, принадлежащих к специализированным породам молочного направлшения продуктивности. / The authors have carried out comprehensive research of morphological and functional features of the mammary gland of the Black-Motley and Ayrshire cattle breeds, which belong to the specialized dairy cow breeds; described conformation features of the Black-Motley and Ayrshire cattle, estimated milk productivity of these breeds; studied morphological and functional properties of the udder, as well as histostructure of the mammary gland of cows, depending on the breed. It has been noted that cows of the Black-Motley breed tend to rather of a dairy type as compared to the Ayrshire breed. The conformation shortcomings of Ayrshire cows include the chest and pelvis narrowness, those of the Black-Motley breed - the lack of firmness in legs and hooves. When used under the conditions of intensive milk production technology, Ayrshire cows are inferior to Black-Motley cows in total milk yield and milk fat. 42 kg more milk per 100 kg of live weight has been obtained from Black-Motley cows. Cows of both breeds have a bulky and proportionally developed udder. Morphological and functional features of the udder of Ayrshire and Black-Motley cows do not differ much. The glandular tissue in the mammary gland of both breeds is well developed. At the beginning of lactation, it amounted to more than 80% of the total udder tissue, which indicates its strong development and characterizes the Black-Motley and Ayrshire cattle as highly productive dairy breeds. The front and the rear parts of the udder of the Ayrshire cattle are developed equally in the main structural elements especially in the total area of milk alveoli, while Black-Motley cows feature more developed rear parts with more visible glandular tissue and larger alveoli. The vascularization degree of the udder parts of both breeds is almost equal. There was almost no developed adipose tissue in the udder of both Ayrshire and Black-Motley breeds observed over the whole period of lactation. Among the studied animals of both breeds, the content of adipose tissue was 0.17-0.49%. In the mammary gland of the Ayrshire cows the greater amount of milk stones was detected than that in their Black-Motley age mates. This may be caused by the fact that the Finnish Ayrshire cattle are probably less adapted to being housed in the dairy plant.