Heat stress can be defined as an increase in core body temperature above its normal range, due to an increase in total heat load that exceeds the capacity for heat dissipation.
Temperature is not the only environmental factor affecting the severity of heat stress.
The THI measures the combined effects of environmental temperature and relative humidity (RH) to ascertain heat load.
↑ Rumen function
↑ Positive energy balance
↑ Antioxidant status
↑ Feed efficiency
↑ Milk yield
↑ Milk composition and quality