An overview of how heat stress impacts dairy cattle fertility

Abstract

Heat stress disrupts dairy cattle fertility by disturbing reproductive tract activities, changing hormonal balance, lowering the quality of a cell in an ovary which may undergo meiotic division to form an ovum, and consequently reducing embryo formation and survival. This review aimed to combine the earlier studies on how heat stress affects dairy cattle fertility. Any dairy herd's performance is affected by its fertility, which is one of the key factors. It is a broad term influenced by many factors, including genetics, food, hormones, pathophysiology, management, and climatic circumstances. The main natural physical environmental factors affecting dairy systems are air temperature, relative humidity, solar radiation, atmospheric pressure, and wind speed. These environmental factors combine to induce heat stress in animals, defined as any combination of environmental variables that causes the temperature to rise above the animal’s thermoneutral zone temperature range. Reduced or exaggerated release of these reproductive hormones can seriously affect the fertility of dairy cattle. Heat stress impact on dairy cattle fertility can be mitigated using relevant scientific procedures, such as physical environmental modifications, food management, and the genetic development of heat-resistant dairy cattle.