Heat tolerance of cattle and the influence of heat stress on economically useful traits (review)

Автор: Pisarenko A.V.

Журнал: Сельскохозяйственная биология @agrobiology

Рубрика: Обзоры, проблемы

Статья в выпуске: 2 т.60, 2025 года.

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Heat stress in cattle due to global climate change is considered one of the most pressing problems in animal husbandry today. Almost 80% of cattle in the world are exposed to high ambient temperatures (M.A. North et al., 2023). A positive correlation between high animal productivity and heat load increases the negative impact of heat stress in the herd, which requires the inclusion of an assessment of cattle heat resistance in breeding work (T. Saizi et al., 2019). Despite numerous studies, assessing the heat resistance of cattle remains a difficult task due to different climatic conditions, differences in feeding and maintenance, breed, productivity and individual characteristics of animals. To quantitatively assess the heat load of the environment, the temperature-humidity index (THI) in various modifications is widely used, which is an indicator that combines temperature and relative humidity, wind speed and solar radiation. The threshold values of the THI vary depending on the animal species, age, physiological condition and productivity. Regardless of the numerical values, the threshold values of the THI are mainly characterized as no heat stress, mild, moderate and severe heat stress. The main biomarkers of animal heat stress are their physiological parameters, such as body temperature, respiratory rate and heart rate. In Australia, in summer, with an increase in the THI to 83, the respiratory rate of Holstein cows increased to 113.1 breaths/min, dyspnea to 2.42 points and body temperature to 41.7 °C (R. Osei-Amponsah et al., 2020). Recently, infrared thermography has been widely used as a non-invasive method for measuring animal body temperature (non-contact and remotely) (M. Mincu et al., 2023; P. Racewicz et al., 2018), which allows detecting heat sources and monitoring their temperature dynamics over time (D. Brezov et al., 2023). Milk productivity can be used to assess animal susceptibility to high temperatures. According to scientists' forecasts, in the Central European and Mediterranean regions, with an increase in cases of heat stress in cows, their milk yield may decrease by 2.8 %, and financial losses of farmers in the summer season may amount to about 5,4 % (S. Hempel et al., 2019). In the USA, Holstein and Jersey cows showed an increase in chloride content in milk at air temperatures above 27 °C with a relative humidity of 99 %, which confirms stress in animals (A.K. Sharma et al., 1988). Also, heat stress is accompanied by a decrease in cow fertility and impaired spermatogenesis in breeding bulls (L. Capela et al., 2022), which is a serious problem among milk producers, leading to an increase in culling of animals and veterinary costs, and a decrease in the genetic potential of the dairy herd (S. Biffani et al., 2016). Genomic selection is considered an effective tool for increasing the resistance of dairy cattle to high temperatures, with the help of which it is possible to classify breeding bulls according to their heat resistance (R. Negri et al., 2023). In general, it is of utmost importance to assess the heat resistance of animals under climate change conditions in different agroecological zones to mitigate the effects of heat stress.

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Cattle, heat stress, heat resistance, economically useful traits

Короткий адрес: https://sciup.org/142245106

IDR: 142245106   |   DOI: 10.15389/agrobiology.2025.2.199rus

Статья обзорная