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.

Finding livestock breeds that are resistant to high temperatures may be one of the strategies for mitigating the impact of global climate change on dairy farming. In this investigation, we studied the heat resistance of Holstein (HB) and Brown Swiss (BS) cows on two commercial dairy farms under the hot summer conditions of Ukraine. The physiological response of animals determined heat resistance by measuring rectal temperature (RT) and respiratory rate (RR) in the morning (from 4:00 to 6:00) in comfortable conditions and the afternoon (from 14:00 to 16:00), during heat load. The temperature-humidity index (THI) was used to characterize weather conditions and microclimate in naturally ventilated rooms (NVBs). BS cows were found to be heat resistant. The reaction of HB cows to the heat was manifested by higher growth of RT and RR, and they suffered significant losses in the daily milk yield per cow in the summer. Further research will need to elucidate the biological and genetic mechanisms of the identified breed differences in heat tolerance of dairy cows.

The increasing variability of weather conditions associated with global climate change is becoming a major problem for dairy farming. The present article provided the results of studies on the relationship between the milk production of Holstein cows and environmental parameters during the warm season. The study investigated whether the relationship between weather conditions (air temperature, relative humidity, wind direction, wind strength, and insolation) and daily milk yield, as well as its components (milk fat yield and milk protein), depended on the conditions comfortable for the cows. The temperature-humidity index was calculated based on air temperature and relative humidity data, which were recorded by the nearest weather station to the farm, which is subordinate to the Ukrainian Hydrometeorological Center. It was found that the relationship between environmental parameters and milk yield was weak concerning the increase in proportion to the growth of heat load. However, the factorial analysis indicated that the total influence of weather factors on milk yield, milk fat, and protein yield was 42-46%. Moreover, weather conditions could significantly impact dairy productivity when cows are kept in naturally ventilated barns. This suggests further investigation of issues related to the microclimate improvement in cowsheds in hot seasons using sprinkler systems for cooling dairy cows.

The temperature–humidity index (THI) remains one of the most widely used tools for assessing heat stress in dairy farming; however, its application is often limited by methodological inconsistencies and insufficient integration with welfare indicators. This study proposes a unified analytical framework for evaluating thermal load at the herd level by combining daily THI values with productivity, feed intake, and clinical indicators such as mastitis and lameness. The analysis was based on two years of herd-level data from a commercial dairy farm with naturally ventilated barns. General linear models (GLM) were applied to assess both direct and delayed effects of heat stress and to compare model reproducibility across years. The results confirmed that maximum daily THI had the strongest association with milk composition and dry matter intake, while cumulative heat load and elevated night-time THI contributed to increased mastitis and lameness incidence. The inclusion of welfare indicators substantially improved the explanatory power of THI-based models, providing a more biologically relevant assessment of heat stress. The proposed framework enhances the accuracy of herd-level monitoring and supports the development of predictive models for welfare-oriented management in dairy systems.

The study aimed to investigate the effect of the drug “Bendamine” on dogs' clinical and morphological parameters in heart failure. Two groups of dogs were formed for research: control (healthy) and experimental (sick). The 30-day experiment included ten dogs from the control group, ten dogs of the observed (unhealthy) spaniel breed, and 10–12 years old dogs. The treatment regimen for sick dogs: furosemide was administered orally on an empty stomach at 2 mg/kg every 12 hours; enalapril was administered orally at 0.5 mg/kg every 12 hours; Bendamine was administered orally on an empty stomach at 20 mg/kg every 24 hours. It is recommended to divide the dose into two doses. In the study of hematopoiesis, we found that erythrocytes in dogs with heart failure increased by 18.2 %, while hemoglobin levels decreased by 1.8 %. Before treatment, red blood cell counts were found to reduce the mean hemoglobin in the erythrocyte and the mean erythrocyte volume. In the experimental group of dogs treated with the “Bendamine”, normalization of morphological blood parameters was found. The number of erythrocytes was 5.8 ± 0.06 T/L, and the hemoglobin level was 143.5 ± 4.7 g/L. The use of the drug “Bendamine” contributed to the gradual restoration of the functional state of the hematopoietic system in dogs with heart failure. This is also indicated by the red blood cell index of the dogs after the course of treatment. The therapy application in the experimental group significantly reduced the frequency and severity of shortness of breath and increased endurance during exercise. There was also a decrease in the frequency and duration of cough attacks. After treatment, signs, and intensity of ascites decreased in dogs of the experimental group. It has been suggested that this is due to an increase in myocardial contractile function due to the positive ionotropic action of Bendamine. The owners also recorded an improvement in appetite in animals after 30 days of therapy. Even in the dogs of the experimental group, after treatment, physical activity and emotional reactions improved. They were less depressed and more inclined to communicate with the owners. Thus, the use of the cardiac drug “Bendamine” in dogs with heart failure positively affected the restoration of hematopoiesis and the normalization of morphological parameters of the blood.

Fatty acids (FA) have a variety of functions in animal bodies. They can be used as metabolic biomarkers, including in pathological conditions. Heat stress (HS) is accompanied by a drop in productivity in dairy cows, resulting from a negative energy balance (NEB), impaired biochemical processes in the body and suppressed immune system. The paper describes the role of individual FAs, the changes in content and ratio of which in serum and milk can be used to assess the physiological state or to predict HS in dairy cows. The purpose of the review has been to show the prospects in the study of the fatty acid composition of biological fluids (blood and milk) to assess the clinical status of dairy cows under HS and the consequences of the possible impact of heat on dairy product quality. Dietary strategies to correct the body's clinical status through dietary FAs have also been mentioned in this literature review.