Seasonal effect on milk productivity and cases of mastitis in Ukrainian Brown Swiss Cows

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.