"Producers may need to adjust their herd management so as to help cows that require birthing assistance."

Wettemann added some calves in the OSU studies were born two weeks early in August, and showed good survival rates provided the newborn calves had access to sufficient shade.

"It's important that newborns be able to cool down and not be stressed," he said.

The OSU animal science studies strengthen consideration for cattle producers to use a fall-calving system with first-calf cows, instead of a spring-calving system.

"Lighter birth weights for fall-calving first-calf cows should decrease difficulties associated with small cows giving birth to large calves," Wettemann said.

In most mammals, the fetus determines when the birth will occur. There is essentially a "time clock" in the calf that determines when the process is going to be initiated.

Recent scientific studies demonstrate that high temperatures can speed up the "time clock" during the last two weeks of gestation, because of hormonal changes in the cow and fetus.

"This is not automatically a bad thing as it can provide certain animal health benefits, but it does require earlier observation of cows during late gestation," Wettemann said.

"When used in conjunction with selection of bulls whose genetics promote lower birth weights, producers potentially can see increased calf survival, and getting a live calf on the ground is the whole point."

Cattle and calves are the No. 1 agricultural commodity produced in Oklahoma, accounting for 46 percent of total agricultural cash receipts and adding approximately $2 billion annually to the state economy, according to National Agricultural Statistics Service (NASS) data.

NASS data indicates Oklahoma is the nation's fifth-largest producer of cattle and calves, with the third-largest number of cattle operations in a state. 

—From Oklahoma State University news release