July and August are considered “the dog days of summer,” and for most cattle folks, a very busy time of the year.

It’s a time when heat and humidity most affect those in the cattle feeding industry, especially in the Midwest and Central regions of the Great Plains. Still, the magnitude of problems vary from year to year, often isolated to specific pockets of the feeding belt.

Presenting at the recent American Society of Animal Science’s annual meeting, University of Missouri scientists estimated heat stress costs the beef industry $369 million annually, while the dairy industry numbers are approaching a billion dollars.

Here are some things you likely did not know about heat stress, and we'll even start them in the form of questions.

Question one – Does it impact quality grade? Because elevated heat reduces feed intake, it would be easy to speculate quality grade would be reduced. As we have looked at windows where temperatures exceeded 100 degrees (F.) for weeks on end, we expected a drop in quality grade. However, a casual observation of weekly grade data showed no effect.

So we asked Dr. Chris Reinhardt, Kansas State University feedlot specialist, to analyze the carcass data in our feedlot database to see if there were any heat/grade relationships. Again, he was not able to show a heat stress impact on grade.

Question two – So if we could provide shade, would you see any benefits? Jerry Bohn, manager of Pratt (Kan.) Feeders, decided to find out. Working with Kansas State University, the team designed a study to split cattle pens so part of the cattle had access to 50×48-foot steel frames with canvas covers. As shown in the table below, shade had little benefit on feedlot performance, but the slight improvement in carcass quality resulted in a slight economic advantage.

Better marbling could be a result of comfortable cattle eating more, Reinhardt speculates. Gain and feed efficiency did not improve, but dry matter intake improved by about 0.55 lb. per day. “That may explain at least a portion of the grade improvement with shade,” he says.

“Extra energy every day above maintenance equals more energy available for retained energy in the form of fat deposition…marbling?”

Bohn’s concluding statement, however, may be the key takeaway: “Sometimes I think we’ll be forced to do things in the future that might not have good economic reasons, but you’ve got to do it the right way.”

Pratt Feeders Shade Study
Feed and Carcass Performance Summary, Cattle Harvested July 2013