Topic: heat stress

MicroRNAs May Play a Key Role in Heat Stress Responses in Mammary Glands of Lactating Cows

MicroRNAs May Play a Key Role in Heat Stress Responses in Mammary Glands of Lactating Cows

A concern facing dairy farmers as the long, hot days of summer approach is the threat of heat stress in their cows. Experienced at temperatures above 80°F, heat stress affects growth and development as well as milk composition and volume. Heat stress is a major cause of low fertility in dairy cattle. It also increases susceptibility to metabolic disorders, mammary gland pathogens and mastitis. Compared with other livestock, cattle are unable to dissipate their heat load efficiently. Additional heat generated by the fermentation of food in the rumen compounds this problem. Cows’ sweating response is not highly effective, and the animals rely on respiration to cool themselves. Because of their inefficient response, cattle accumulate a heat load during the day that must be dissipated in cooler nighttime temperatures. In extreme weather conditions with overnight temperatures above 70°F, however, this doesn’t happen. Cattle experiencing increasing heat stress will stop feeding and become restless. They will then begin drooling and breathing more rapidly and with increased effort. They will also begin to group together, further exacerbating the problem. If not controlled, severe cases of heat stress will result in death. Economically, decreased milk yield and reproductive losses through hot summer months seriously affect the dairy industry. Increased occurrences of extreme weather conditions caused by ongoing global warming will only worsen these losses. Read More...

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