Keeping cows in their thermoneutral zone – 41 and 68 degrees –
can minimize the impact of seasonal changes on milk production,
reproduction, feed efficiency and income-over-feed cost, said
John Smith, a dairy science Extension specialist in the
Department of Animal Sciences and Industry at Kansas State
University. Speaking at the Cornell Fall Dairy Conference last
year, Smith pointed out the negative and well-documented impacts
of heat stress to a dairy’s bottom line. “When daily milk
production is reduced 2 to 12 pounds per day per cow, the gross
income loss related to heat stress ranges from $32.40 to $324
per cow,” Smith said. Heat stress not only lowers milk
production during summer months but also reduces the potential
for future milk production. “For every pound of peak milk
production that is lost, an additional 250 pounds of production
will be lost over the entire lactation,” Smith said. What’s
going on with cows during heat stress? When housed in an
environment beyond their thermoneutral zone, they a