Livestock: May 2003

The main focus in beef cattle herds this time of year is the breeding season, and rightfully so. Every common measure of cow/calf production or return starts with a successful breeding season. Regardless of how well you manage the herd during calving, suckling phase, weaning process, or beyond, conception rate is the primary factor in a successful cow/calf enterprise. You must do all you can to enhance conception.

Conception rate is critical to the success of a cow-calf enterprise.

So, what does it take for upper level conception rates? Of course, one factor is a sound, fertile, willing, healthy bull battery of adequate number to cover the herd. On the cow side, the primary factor affecting conception rate is nutrition. The cows must be in a body condition score (BCS) 5.0 to 5.5 at breeding, which means they were a BCS 5.5 to 6.0 at calving. They also must be on a positive plane of nutrition for the foreseeable future. When things are right, you can expect over 90 percent of the cows exposed to conceive in a limited breeding season.

It?s May 2003. The breeding season is upon us, and some bulls have already gone out with cows. What can be done at this late hour to enhance conception rates if cow condition is less than ideal? Here are three management practices that are commonly used.

1. Flushing thin cows.
   Research shows that cows in BCS 4 can be "flushed" with a high quality ration just before and during the early part of the breeding season. Ideally, flushing begins at least two weeks before breeding and continues at least a month into it. The ration must enable cows to maintain body weight or gain slightly during that time. This practice can help BCS 4 cows attain conception rates of those cows in BCS 5.
    
   
2. Short-term calf removal (48 hours).
   Physically separating young calves from their dams for a short period can stimulate estrous in borderline BCS 5 cows. During this period, calves are provided easy, free-choice access to palatable feed and fresh water. Research has shown that this practice can increase conception rates by as much as 8 percent and has no negative affect on calf weight at weaning (even if implemented mid-season.)
    
   
3. Early weaning calves (6 to 8 weeks of age).
   Note: Although this practice has been proven to be effective, it probably should be implemented only in extreme emergencies. Lactation can roughly double a cow?s protein and energy requirements. Stated another way, if her calf is weaned during peak milk production, her nutritional needs can be cut in half. If a herd is in a BCS 4 or less at the beginning and during the breeding season, conception rates will be unacceptable — 40 to 60 percent or even lower. Early weaning can drop the cow?s nutrient requirements to levels that will allow estrous activity again. Handling 6-8 week old calves might concern some producers. However, research conducted primarily at Oklahoma State University has resulted in detailed guidelines for managing the process.