Alleviating heat stress is critical to milk production.
Heat stress from high environmental temperatures
can be compounded by mistakes in managing and
feeding the cows.
Water is your first concern during periods of high
temperatures. Water physical properties—heat conductivity
and latent heat of vaporization—help transfer
heat from the body of the animal to the environment.
Dry matter intake of lactating cattle is affected when
ambient temperatures are outside of the cow’s “comfort
zone” (41 to 68 F). When ambient temperatures
increase beyond 68 F, the cow typically goes off feed.
Dry matter intake can decrease by 0.17 lb for each
degree above 68 F. During severe heat stress, total
intake and milk production may decrease by more
than 25%.
It is estimated that for every 1 lb decrease in dry matter
intake 2 lb of milk production are lost.
Some responses of cattle to heat stress, such as panting,
may actually increase heat production in their
bodies. Other changes, such as reduced dry matter
intake, selective consumption (higher energy dense
feeds), reduced activity, reduced metabolic rate, and
cooling strategies, will reduce heat production.
C O L L E G E O F A G R I C U L T U R E & B I O L O G I C A L S C I E N C E S / U S D A
ExEx 4024
Dairy