Global Climate Change Effects on Milk Yield and Composition of Dairy Cattle

Abstract

Solar radiation, air movement, relative humidity, and temperature are environmental variables that affect
the well-being of dairy cows. However, the two primary factors influencing animal production are relative
air humidity and temperature. When the temperature increases outside, cows must sweat and pant more to
maintain their coolness, as their main non-evaporative cooling mechanisms (convection, conduction, and
radiation) become less effective. During humid and warm conditions, heat stress can occur when the body’s
ability to dissipate heat into the environment is insufficient compared to the amount of heat produced by
metabolism. Dairy cows under heat stress can experience a range of costly and dangerous side effects.
Elevated ambient temperatures and increased temperature-humidity index above acute thresholds are
associated with reduced feed intake, as well as milk production and milk efficiency