Calving difficulty not only is the prime cause of baby calf mortality, it can also markedly reduce a cow's reproductive performance during the next breeding season, according to Glenn Selk, Oklahoma State University Cooperative Extension emeritus livestock specialist.
Selk cited a 1973 study by animal scientists J.S. Brinks, J. E. Olson and E.J. Carroll that documented cattle suffering from calving difficulty had pregnancy rates decreased by 14%, while those that did become pregnant calved 13 days later than projected as their next calving.
"Watchful producers willing and able to lend a hand often make all the difference," he said. "Results from a 1984 Montana study showed that heifers receiving assistance in early stage two of parturition returned to heat earlier in the post-calving period and had higher pregnancy rates than heifers receiving traditionally accepted obstetric assistance."
In this study, heifers were either assisted about one hour after the fetal membranes appeared or were assisted only if calving was not completed within two hours of the appearance of the water bag.
"Heifers that were allowed to endure a prolonged labor had a 17% lower rate of cycling at the start of the next breeding season," Selk said. "In addition, the rebreeding percentage was 20% lower than their counterparts that were given assistance in the first hour of labor."
First-calf heifers should deliver a calf in approximately one hour. The starting time is the first appearance of the water bag and ends with complete delivery of the calf. Mature cows that have calved previously should proceed much faster and deliver the calf in about a half hour.
"Prolonged delivery of a baby calf – a delivery in excess of 90 minutes to two hours – often results in weakened calves and reduced rebreeding performance in young cows," Selk said. "Always check and be certain that cervical dilation has been completed before starting to pull the calf."
A cow-calf producer who is uncertain about whether or not cervical dilation has taken place, or whether or not the calf is in a deliverable position, should contact his or her veterinarian immediately.
Source: Oklahoma State University