VETZOO Veterinarija ir Zootechnika 2669-2511 1392-2130 LSMU PENEV Review Article Influence of Heat Stress on Some Physiological, Productive and Reproductive Indicators in Dairy Cows – A Review Stojnov Martin Department of Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria Dimov Dimo Department of Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria Penev Toncho tonchopenev@abv.bg ∗∗∗ Department of Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria Marinov Ivaylo Department of Animal husbandry – Ruminant animals and animal products technologies, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria Mitev Jurii Department of Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria Miteva Chonka Department of Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria Uzunova Krasimira Department of General Livestock Breeding, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria Corresponding author. 80 2 1 9 27 02 2023 27 02 2023 17 05 2022 24 08 2022 22 09 2022

The purpose of this review is to examine the scientific literature on the effects of heat stress on some physiological, productive and reproductive parameters in dairy cows. The article analyzes the scientific papers in which the influence of heat stress and its impact on some indicators is studied. As a result of the review, it became clear that heat stress has an impact on the studied indicators, but there are no clear criteria at which values of temperature-humidity index (THI) this effect is registered. The relationship between heat stress, productivity, successive lactation and physiological and reproductive parameters in dairy cows is still controversial. This poses a challenge, through research, to solve the problems in regards to high temperature and animal welfare and productivity for specific climatic conditions.

 Heat stress dairy cows physiology productive reproduction