While beef producers place major emphasis on calving ease and achieving healthy, live births, those traits often take a back seat to milk production and other, more highly valued traits in the dairy industry.
That’s unfortunate, argue researchers at Colorado State University (CSU) College of Veterinary Medicine and Biomedical Sciences. Especially because dystocia – difficult or delayed birth – is itself detrimental to the dam’s ability to produce milk and milk fat, especially in the first 30 days of lactation. Other negative impacts include increased calf illness and death loss; decreased fertility in the dam; and increases in infection, illness and future calving problems for the dam.
In a comprehensive document on calving and calf care on dairy farms, the CSU researchers cited data from U.S. dairy operations over one year indicating that 18% of heifer calves from dams across all parities required assistance, while 32% of first-calf heifers needed assistance. A more localized study on Colorado dairies showed overall dystocia rates of 30-40%, with rates of more than 50% for first-calf heifers. In contrast, a study of U.S. beef operations showed a dystocia rate of 3% for second-parity-and-higher beef cows, and 17% for beef heifers.
A number of factors can cause dystocia, including oversized calves, malpresentation of the fetus, fetal deformity, overconditioned dams; and poor uterine contraction due to milk fever (which usually is not a problem in heifers). Because heifers are still growing, their pelvic structure is smaller than that of a mature cow. The tissues of the birth canal (cervix, vagina and vulva) also never have been dilated. Excess fat deposition around the pelvis also can narrow the birth canal, which is why it is so important to manage body condition in heifers.
Often manually dilating the vagina and vulva will be enough to assist first-calf heifers. In this highly visual primer on calving assistance, Pennsylvania State University researchers note that heifers may naturally take slightly longer to calve. They recommend intervening after heifers have been in active labor with feet showing for 60-90 minutes, compared to 30-60 minutes for higher-parity cows.
The CSU researchers recommend preventing dystocia through more careful sire selection when mating heifers, as well as managing nutrition to prevent heifers from becoming too fat. Training personnel to assist difficult calvings also is important, as is careful observation so timely assistance can be provided.