Wednesday, March 31, 2010

Dairy Cattle Management in a Hot Environment

I have my temperature widget on my desktop and noticed that it's getting hotter and hotter every day. Temperature would range from 30 to 35 degrees centigrade on a daily basis and this affects dairy cattle management or backyard cattle raising.   

Hot environments affect the performance of dairy cattle both directly and indirectly. To attain the fullest genetic performance, environmental conditions and diets should be modified. Thermal factors consist of air temperature, humidity, air movement, and radiation rate. In lactating Holstein cows, the comfortable temperature is within the range 4-24oC (Hahn 1981). The effects of heat stress on the cows begin to be observed above 24oC, and milk yield decreases markedly above 27oC (Johnson 1965).

A decline in milk yield, fertility, and growth rate in hot environments is closely related to an increase in body temperature (BT). BT results from the balance between heat production (HP) and heat loss (HL). Since humidity affects the HL from an animal under high temperature conditions, dairy cattle performance falls markedly in hot, humid summers. Moreover, HP is associated with feed intake level, which in turn affects the production level. In high-producing cows, the HP is higher, and the effect of a hot environment is more pronounced. More.
Image source here.