Plant Extracts to Alleviating Heat Stress in Dairy Cows

SIMPLE SUMMARY: Climate change and environmental heat stress are important challenges for the future of the dairy industry, as these environmental factors can reduce the productive and reproductive performance of dairy cows. Therefore, relieving the heat stress of dairy cows is an important priority for the dairy industry. Plant extracts have advantages in safety, efficiency, low toxic side effects (if correctly selected) and residue, thus, can significantly aid in alleviating heat stress in dairy cows. This paper reviews the effects of some plant extracts on alleviating heat stress in dairy cows and their possible regulatory mechanisms. The aim is to develop applicable strategies using plant extracts to alleviate heat stress in dairy cows. ABSTRACT: Heat stress (HS) in cows is a critical issue in the dairy industry. Dairy cows accumulate heat from body metabolism, along with that imposed by air temperature, humidity, air flow and solar radiation. HS in animals can occur during hot and humid summers when the ambient temperature is extremely high. Dairy cows have relatively high feed intakes and metabolic heat production and are thus susceptible to HS, leading to reductions in feed intake, lower milk yield, affected milk quality, reduced animal health and even shortening the productive lifespan of cows. Therefore, alleviating HS is a top priority for the dairy industry. Suitable plant extracts have advantages in safety, efficiency and few toxic side effects or residues for applications to alleviate HS in dairy cows. This paper reviews the effects of some plant extract products on alleviating HS in dairy cows and briefly discusses their possible mechanisms of action.