Seasonality affects milk production, its composition, as well as the spread of mastitis in dairy cows. The aim of the research work was to study the way the seasons affect milk productivity and the manifestation of mastitis among Ukrainian brown Swiss cows at a commercial dairy unit, with the animals kept in naturally ventilated premises. The relationship between the indicators was assessed by Spearman’s rank-order correlation coefficient. The influence of a seasonal factor and individual air parameters on cows’ milk productivity was evaluated using Factorial ANOVA in Statistica 12 software. The results of the study revealed a high correlation between the content of milk fat and milk protein and the weather conditions (temperature, relative humidity, as well as temperature-humidity index) by seasons. Moreover, the greatest negative relationship between these characteristics was observed in spring (r = 0.4‒0.8) and in autumn (r = 0.6), and not in summer during the heat, as we had predicted earlier. The influence rate of the «season» factor was significant both in terms of the daily milk yield and milk components (51–59%) and mastitis prevalence rate in cows (56%) at the dairy unit. In general, the reduction of milk yields in summer and especially in autumn, and the spread of udder pathology in cows during this period should provide for the introduction of managerial and preventive veterinary measures to mitigate the effects of hot summer among Ukrainian Brown Swiss cows at year-round housing of animals in naturally ventilated premises.

Наведено результати реалізації продуктивних якостей корів голштинської породи упродовж інтенсивної експлуатації з високою концентрацією тварин на обмеженому просторі та мінімальними можливостями для відновлення і відпочинку. Дослідження показали, що за нормальної тривалості лактаційного періоду генетичний потенціал молочної продуктивності реалізується з віком корів. Ось тому відносно найнижчий рівень удою мають первістки (7747,7 кг), у другу лактацію він зростає на 9,89 % (Р<0,001) і набуває свого максимального значення у третючетверту (9422,2-9694,3 кг), після чого підтримується на одному рівні упродовж п'ятоїшостої лактації (9665,4-9499,3 кг). Така ж динаміка синтезу молочного жиру та білка: найнижчі значення характерні первісткам, а найвищі-коровам четвертоїп'ятої лактації. За нормальної тривалості лактаційного періоду не встановлена кореляційна залежність між удоєм і живою масою корів. Від'ємний індекс адаптації тварин відносно інтенсивної технології експлуатації становить у середньому 2,9-3,3.

The article set out the materials of researches about the formation of the level of milk production of Austrian cows of Schwyz breed of different generations, depending on the genotype and paratypic factors at their area of ecological origin, considering of which will promote high selection. It was established that in the operation of animals in the area of environmental origin the level of lactic productivity of daughters varies between 5000 – 12000 kg per lactation, whereas their mothers do not exceed maximum index 12,800 kg, at the same time in the mother of father it exceeds 20000 kg. Thus, the qualitative composition of milk from different generations corresponds to the average consolidated of Schwyz breed. The mass part of the fat and protein in the milk of daughters is at the level 4,13 and 3.57%. The highest content of milk fat in mother of father, the mass of fat in the milk is an average of 4.37%. The dynamics of the implementation of milk production of daughters and their mothers on the continuation of the economic use is similar. In the first lactation the total milk yield of cows amounts respectively 6686.9 and 6261.8 kg of milk, in the second lactation, the level rises to 7532.2, and 7748.7 kg. In the future, there is a slight increase in the productivity and after the fourth lactation daughters and their mother’s milk yield is almost identical and is respectively 8138.3 and 81356 kg of milk. The implementation of the genetic potential of the father's mother passes on a higher level, that meet the requirements for this category of parent. In the first lactation from this cows was obtained 9276.3 kg of milk, and the second – 11599.6 kg. The highest level of productivity was observed in the third lactation where milk yield was an average of 11667.5 kg. After the fourth lactation milk yield decreased slightly, but did not fall below the figure 11139.3 kg. It is proved that the realization of the productive potential of the daughters of parents of highly close to that of a mother. If the productivity of the daughters of the average for the entire period of exploitation below the milk yield of their mothers only 87 kg, 4% milk, the index mother of father – to 3762 kg, or 48.5% (P < 0.001).

The intensive conditions of industrial milk production require animals with a strong constitution and health, in order to maintain high levels of productivity and reproduction over a long period of time. The aim of the research was to determine the peculiarities of realization of the genetic potential of dairy productivity by cows during commercial exploitation in the industrial complex. An experimental part of the research was conducted on the industrial complex for the production of milk of Holstein breed cows of private JSC "Agro-Soyuz" (Ukraine) on healthy animals, which were formed in six groups from the first to the sixth lactation. With the intensive technology of exploitation in the industrial complex, the lactation activity of first-heifers and full-age cows varies within the range of 439.6-446.7 days, and the calving-to-calving interval is 497.3-506.3 days. At the same time, the relatively low milk productivity is characterized by first-heifers, in which the milk yield is 9,439.2 kg of physical or 9,091.6 kg of 4% milk, whereas in animals of the second lactation, these indicators are higher respectively by 10.03% (P < 0.05) and 11.17% (P < 0.01). In the fourth lactation observed further increase of milk yield, reaching the level of 11,725.3 kg of physical or 11,455.4 kg of 4% milk, which is more than the index of cows at third lactation, respectively, by 10.96% and 11.72%. Substantially higher milk productivity in cows at fifth lactation is 11,960.0 kg of physical or 11,833.9 kg of 4% milk, which is higher than the animals of the third lactation, respectively, by 12.70% and 14.54%. The highest milk yield have Holstein cows in the sixth lactation-12,071.1 kg of physical or 11,919.9 kg of 4% milk, which is more than the animals of the third lactation, respectively, by 13.51% (P < 0.001) and 15.16% (P < 0.001). The production of milk butter and protein is the lowest in first-heifers and is an average of 661.2 kg. In animals of the second and third lactation, these products are higher respectively by 11.39% (P < 0.01) and 10.77% (P < 0.05), and in animals of the fourth to sixth lactation, by 20.72% and 22.96%. With the extended lactation activity, the correlation relation between live weight and total milk yield in first-heifers and cows of the second lactation is positive and is, respectively, r = 0.509 and 0.202. Instead, in cows of the third-sixth lactation, such the relation is negative and r = 0.339-0.163. In general, lactation animals of all ages are characterized by satisfactory adaptive properties: in cows in the fourth to fifth lactation, the adaptation index is on average-8.7 ± 0.34 units; in animals of the second-third lactation-respectively-9.6 ± 0.37 and-9.8 ± 0.53 units. The lowest value of adaptation index has first-heifers (-10,5 ± 0,44 units), and relatively the highest-in animals of the sixth lactation-8,3 ± 0,24 units, which is less than the value of first-heifers on 26.51% (P < 0.001). The value of adaptation index has a functional relation with the total milk yield of Holstein cows of a...