Global Climate Change Effect on the Reproductive Efficiency of Dairy Cattle

Abstract

Global warming has a detrimental impact on the welfare and productivity of dairy cows. In many regions around the globe, farm animals experience significant material and financial losses as a result of climate change, particularly during the summer months. Dairy cattle experience heat stress (HS) when external temperatures exceed the thermo-neutral zone (comfort zone), which is defined by the range between the lower critical temperature and the higher critical temperature. The lower critical temperature is the ambient temperature at which an animal begins to produce excess metabolic heat to regulate its body temperature. The higher critical temperature refers to the temperature at which an animal raises its body temperature to make up for inadequate evaporative heat loss. Animals that are exposed to temperatures higher than their thermo-neutral zone will experience HS as a result of a confluence of environmental factors. HS represents a significant financial challenge in many dairy-producing regions around the world, as it negatively affects various reproductive traits and diminishes the milk production of dairy cows. The decline in age at puberty, estrus induction, conception rate, oocyte fertility, follicular development, embryonic development, abortions
and fetal loss, pregnancy, and also male reproductive performance observed in dairy cows during the hot summer months is primarily attributed to global warming.