Some heat-stressed cows are delivering premature calves and doing it ahead of normal fall-calving season.
The heat and severe drought this year could make fall-calving season as labor intensive as winter calving, say University of Missouri Extension specialists.
"Cows under stress need to be watched closely," says David Patterson, MU beef reproduction specialist.
Therefore, beef producers should start watching their cows before the predicted calving date.
Eldon Cole, extension livestock specialist at Mount Vernon, Missouri, agrees. He says he's seeing some calves arrive a month earlier they were planned.
Patterson says cows under stress reduce blood flow to the uterus, triggering premature calving.
"When nights do not cool down, the cow's body does not reach a thermo-neutral state. The heat stress builds," he says.
Justin Sexten, MU beef nutritionist, explained cows in their seventh or eighth month of pregnancy already face stress carrying the calf. Temperatures that top 100 degrees F add to that stress.
Further, cows on poor pasture may not be getting adequate nutrition.
"Over-mature pastures will provide too much fiber and not enough energy. Fiber digesting in the rumen creates more heat," Sexten says.
A cow's rumen needs protein to keep microbes working, digesting fiber.
Clean water becomes ever more important for cows in heat and cows that calve early and need to produce milk. Shade also helps them.
In contrast, Sexten says cows approaching calving dates should be on a rising plain of nutrition.
On drought-dried pastures, cows may not get enough energy in their diet to produce milk at calving. On the cow herd at the MU Beef Farm, Columbia, Mo., Sexton started supplemental feeding a pound of distillers' by-product grains to add protein and energy to the pasture ration.
Premature calves are small and weak, Cole says. To add to the problem, the cows did not have milk. The calves need colostrum, the first milk that contains the antibodies for health protection, and they need hydration.
"Cows don't always pick an ideal spot to drop their calf," Cole says. "They may not be under a shade tree."
Temperatures over 100 degrees F and relative humidity down at 20% dehydrate calves.
"When calving in winter, farmers pick up calves and put them under the heater in their pickup truck," Cole says. "They may need to put them under the air conditioner now."
Cole says he was alarmed when the first early-calving reports came in, as death losses were high. However, he says other producers are having calves born closer to predicted dates, within two weeks early, he adds.
Good weather and moderate temperatures the last couple years in August have tempted beef producers to push breeding and calving dates earlier, Cole says.
Many cow herds that once calved September 1 are now due in August.
Ultimately, these "summer calves" may need as much management attention as winter calves.
Patterson adds that cows bred to calving-ease bulls often calve early anyway, so they should receive an extra dose of vigilance.
This year and in the future, Sexten recommends delaying breeding fall-calving herds until December 1. "Many people have backed up to breeding at Thanksgiving," he says. "Calving earlier is riskier."