Is hot weather taking a toll on your reproduction program?
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Don't let hot weather hurt reproduction

July 07, 2013
POSTED BY: Richard Wallace | DVM, MS | Managing Veterinarian | Dairy Technical Services | Zoetis

Is the hot weather taking a toll on your reproduction program? Steve Smalley VMD, MBA, recommends evaluating these key measures:

  • Pregnancy rate — Although most herds will decline during the summer months, a realistic goal is a 21-day pregnancy rate within two to three percentage points of the herd’s yearly average.
  • Calving distribution — When reproduction begins to slip, calving due dates can become more bunched, stressing transition and calving facilities. Be sure to properly prepare for a calving surge.
  • Body temperature monitoring — Conducting a heat audit using vaginal thermometers can provide insight into heat stress. Internal temperatures over 103ºF will result in more early cases of embryonic death.

Heat-stressed cows are prone to a reduced expression of estrus and are at a greater risk of infertility. Excessive temperatures also can cause early embryonic death. As heat rises, feed intake declines, providing fewer nutrients to support reproduction.

“As evening temperatures start to drop, it’s important for producers to assess the reproductive status of their herd and begin to aggressively work to breed cows back,” Smalley says. “Cow cooling should be our first priority when combating heat stress. Start with exit lane cooling and then focus on making cows comfortable in the parlor.”

Producers also should not overlook the importance of water intake, he says.

“I recommend placing water troughs in the exit lane from the parlor,” Smalley says. “Cows will consume more than 30 percent of their daily water intake within a half hour after milking. It’s important to provide easy water access at that time.”


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