Hot weather continues; keep an eye on milk production and composition

Temperatures in much of the U.S. are expected to be in the upper 90s or lower 100s for the foreseeable future, creating extra challenges for dairy farmers.

“Obviously, when it gets as hot as we’ve been having, it will have some effect on cows and milk production,” says Mike Bragg, agent with the Dallam-Hartley County Extension Office in Dalhart, Texas.

“It will affect milk production a little bit, but as long as (the cows) are well-managed, they will get through it OK,” Bragg says. Most of the dairy cows in the northern Texas panhandle are under roof with adequate water and supplemental cooling, he points out. “It’s just a little warmer than they would like it to be.”

Kevin Lager, Texas AgriLife Extension dairy specialist, says the heat has had an impact on somatic cell count and milk fat — “more so on milk fat than SCC,” he says, “as the dry weather has actually helped with milk quality in some cases by reducing the exposure to some of the environmental strains of mastitis-causing agents. Milk fat percentages have been reduced by almost three-tenths in some cases; for example, a decrease from 3.5 to 3.2 percent.”

Indeed, heat stress can have a significant impact on milk composition, points out Maurice Eastridge, professor and extension dairy specialist at The Ohio State University. He cites the following:

• Milk fat percentage often decreases during heat stress. Cows may be sorting through the feed, reducing fiber intake. Or, cows may be losing saliva via panting, which could mean less buffer entering the rumen.
• Milk protein percentage also may decrease during heat stress. With the reduction in dry matter intake, there is reduced amino acid intake and consumption of fermentable organic matter, which can reduce microbial protein synthesis.
• The somatic cell count often increases during the summer, which results in reduced milk yield and can lead to a reduced price for the milk. In addition to the pathogen load increasing, the cow’s ability to fight the infection may be compromised during heat stress.
•  Milk urea nitrogen often changes during the summer. Typical concentrations should be 10 to 15 mg/dl; however, changes even within this range can signal problems.

Changes in milk composition should be monitored as frequently as the data are available, Eastridge says. Changes in milk fat may be occurring within groups but not the bulk tank (or the overall head average from DHI), so changes should be monitored within groups and for the herd.

 

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If given a chance, would a cow choose to live in the Texas panhandle? Southwest dairies should migrate to NY and New England ... cool temps, plenty of rainfall, high taxes, cold winters and happy holsteins. All you need to do is bulldoze the hills and woods and re-clear all of the land that was abandoned since the 1950's. We're the future of agriculture ... in our dreams. It may just happen someday ... deserts and water shortage are not good for plant growth, eh?