This experiment was conducted to study the effect of a prolonged hot period on the fatty acid (FA) composition in blood serum of dairy cows. Eighteen multiparous Holstein cows were randomly assigned to the hyperthermia group (HYP, n = 8) in August (summer season) and the control group (CON, n = 10) in October (autumn season). Blood from animals of the HYP group was collected in one heat wave, which was preceded by a long period of heat stress (HS, temperature-humidity index (THI ≥ 72)). Blood from cows of the CON group was collected under thermal comfort conditions (THI < 68). The spectrum of free fatty acids (FFA) in the blood serum was analyzed by gas chromatography. The concentration of FFA increased, including saturated FAs and monounsaturated FAs, in the blood serum of cows under conditions of prolonged HS. This was associated with the mobilization of FA into the bloodstream from adipose tissue, as a consequence of negative energy balance. An increase in the ratio of n-6/n-3 polyunsaturated FAs may indicate biomembrane dysfunction and adversely affect dairy cows. This study showed that prolonged periods of heat can affect the FA composition of blood. How much this leads to changes in the FA composition of milk and the quality of food products remains to be seen in further research.
The problem of free radical pathologies in high temperatures in animal husbandry and veterinary medicine is extremely important scientific and practical. In the process of hyperthermia, the structure of cell membranes, the permeability of membranes, and membrane transport systems change, which cause the oxidation of unsaturated fatty acids and the accumulation of toxic products of a radical nature. This plays an important role in the development of many pathological conditions. The review article describes the problem of the influence of heat stress (HS) on a living organism and the problem of hyperthermia in animal husbandry. Emphasis is placed on the role of the body's antioxidant system in a state of HS and the use of antioxidant drugs as additives into feed for farm animals, aimed at mitigating the course and harmful effects in HS. On the one hand, our goal was to describe in an accessible form the main complex biochemical disorders in the body under HS conditions, which lead to a deterioration in the welfare and loss of productivity of animals. On the other hand, we tried to show the special role of the antioxidant defense system in preventing the development of oxidative stress in its classical representation. Also, we substantiated the choice in favor of using natural and synthetic antioxidants as one of the strategies for the prevention of HS in modern animal husbandry.
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.
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