Pregnancy Loss:
A Virginia Perspective
There are plenty of reasons why bred cows or heifers might suffer pregnancy loss or fail to deliver a viable calf. Causes of pregnancy loss among Virginia beef herds were discussed by Virginia Tech Extension Veterinarian John Currin during the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium Oct. 15-16 in Staunton, Va.
Currin said reasons for abortions, stillborn and weak-born calves are often relatively easy to diagnose. More frustrating are cases involving failed pregnancies for which determination of cause is uncertain. For many such cases, Currin suspects multiple factors are involved.
Experimenting with tub-grinding hay, John Currin says he wasted more in diesel than he saved in hay. A higher fiber content of the mixed ration resulted in a lower dry-matter intake than expected and, therefore, a lower energy intake. The Virginia Tech Extension veterinarian cautioned producers to test the quality of such rations, paying attention of NDF rather than crude protein or energy.
According to Currin, fall calving is popular in Virginia and more producers are calving earlier than before, in July and August. Also increasing is the practice of fencing cattle away from ponds and waterways. This is laudable for protection of water quality, but it often results in cattle being fenced away from shaded areas near the water. So calving in the summer and less opportunity for cattle to find heat abatement may be contributing to pregnancy losses.
“The best theory is that it is a multiplex problem involving heat, endophyte-infected fescue and immune system function,” said Currin. “I think it is most likely a combination of those factors. It probably won’t happen every year, but it is likely to happen again.”
Hot weather and associated fescue toxicity problems are facts of life in Virginia. There is little, if any, relief from heat stress when cattle do not have access to shade. Additionally, cattle grazing “hot” fescue pastures can experience nutritional stress due to reduced forage intake and reduced forage quality. The cumulative challenge can be great for cows in late-gestation and during the calving season, particularly if immune function has not been optimized through an appropriate vaccination program.
For herds in which problems exist, but definite answers have been elusive, Currin offered the following recommendations:
- Make sure cattle have access to shade, as well as ample fresh water.
- Seek forage alternatives for cows grazing toxic fescue during late gestation.
- Consider adjustment of calving season, perhaps avoiding July and August.
“I think we all need to consider why we are doing things the way we are, and also consider the potential negative consequences,” Currin stated.
Currin spoke during Wednesday's ARSBC session focused on dealing with pregnancy and birth losses. For more information, visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation and to view his PowerPoint slides and proceedings paper.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force.
