Missouri Dairy Business Update

Volume 17, Number 6
June 2017

Heat Stress has Lasting Impacts, Years Down the Road

Humidity has started to creep up on us as summer heat begins to set in. A group of dairy producers gathed under a newly constructed dry cow facility at Martin’s dairy in Humansville, MO for Missouri Dairy Industry Alliance (MDIA) field day in early June to discuss reasons to manage Missouri’s heat stress and solutions they can implement right away.

Experienced dairy producers would tell us that when the cows aren’t comfortable and cool, a decline in milk in the tank starts to creep in. Unfortunately, it is not rare for the vulnerable herds to experience 10-20% decline in milk production during the hottest of times.

That’s not the whole story.

Research recently released from the University of Florida helped paint a picture of the long-term impact of heat stress. They focused on the dry cow. A question many never thought to ask, “What happens to the calf inside the heat stressed dry cow?” 

Looking at five years’ worth of data, cows during their 46 day dry period who were provided access to shade (heat stressed) were compared to cows provided shade, sprinklers and fans (cooled). The average summertime temperature, 75°F.
They found this vulnerable developing heifer calf inside the heat stressed dam was:

In addition to loosing the milk production immediately from the heat stressed dam, the dairy is hit with a double wammy - her heifer produces less too, two years later!

Perhaps the most concerning part of this data, is the researchers expect a phenomenon called fetal programming is to blame for the decline in performance between the heat stressed calf and the cooled. This means, the DNA of the calf born from a dam who was heat stressed is permanently changed to be metabolically different from her cooled peers. 

It’s time to take control of your herd’s heat stress. There are very few scenarios where the return doesn’t pay back the investment rapidly, when using a model that only looks at the milk loss on the year of heat stress. Adding in the impact on the unborn fetus, heat stress is beginning to compete as one of the most costly issues in the dairy industry.

The University of Missouri Extension is your one-stop source for practical education on almost anything. To learn more about dairy cattle heat stress effects and abatement, visit:http://dairy.missouri.edu/stress/ or contact your local University of Missouri-Extension dairy specialist Reagan Bluel at 417-847-3161, BluelRJ@missouri.edu or Ted Probert at 417-547-7545, ProbertT@missouri.edu