Rebreeding Reminders
Expert offers tips for prepping young beef cows for rebreeding.
As spring moves into summer and breeding season replaces calving season, it's an important time to keep a close eye on the young females in your cow herd, points out Jason Ahola, an Extension beef specialist with the University of Idaho.
First- and second-calf females need to be managed closely in spring and summer, Ahola says, to avoid a large number of open females in the fall and to reduce dependence on high-cost bred replacements.
Jason Ahola
He adds that ensuring that these young females rebreed can help maximize the number of calves to be sold during 2010 and beyond — a time when calf prices are forecast to be rebounding.
Ahola offers this list of management reminders that may help producers improve the reproductive performance of their young beef cows:
1. Monitor body condition
According to USDA National Animal Health Monitoring Service (NAHMS) survey data, 42% of cows lost weight from just after calving (7 days after) until weaning time. This loss of body weight occurred primarily during the time of year when forages were most available and typically at their highest quality, which also occurred during the breeding season, Ahola points out.
"It is crucial for producers to monitor changes in both body weight and body condition score (BCS) in young females from calving through breeding to avoid weight loss during this time of elevated nutritional need," he says.
To avoid weight loss, he suggests supplemental energy and/or protein should be provided.
2. Develop and use a ration
Because of elevated nutrient requirements, Ahola says many young beef females would benefit from supplemental energy and/or protein from precalving through breeding since they become pregnant early in the breeding season.
He adds that, with current computer-based ration formulation programs, this strategy is relatively easy and very low-cost (several are free; check with your local university Extension).
"A properly formulated ration ensures that the nutritional needs of a female are met in order to optimize performance," Ahola says. "A ration also helps to reduce feed costs by reducing the amount of overfeeding, especially protein." Ideally, he adds, a forage analysis should be completed prior to ration development to ensure that the calculated ration is accurate.
Additionally, Ahola reminds producers that several trace minerals are important for reproduction as well. There is strong evidence that supplementation of copper, zinc and manganese can affect pregnancy rate early in the breeding season, compared to not supplementing these trace minerals, he says.
3. Use bull exposure
Ahola says the number of young females cycling at the start of the breeding season can also be improved via exposure to vasectomized bulls. "Exposing females to bulls beginning 30 to 45 days after calving can stimulate (or hasten) cyclicity in some females," he says.
Similarly, the use of commercially-available hormones — such as melengestrol acetate (MGA) or controlled internal drug release (CIDR) devices — to increase the percent of young females cycling prior to breeding have also been evaluated. However, Ahola says results have been inconsistent and the cost-benefit of using these products to stimulate cycling needs to be considered.
4. Consider weaning early
Lastly, weaning calves early from young females may have more of an effect on reproductive performance compared to all other strategies combined, due to its substantial effect on body condition, Ahola says.
However, Ahola says recent NAHMS data indicates that most beef producers decide their weaning time based on calf performance, and not on cow condition.
Ahola tells producers that improved reproduction can result if calves are weaned at the start of the breeding season (e.g., 90-100 days of age) or early in the breeding season (e.g., 110-120 days of age). In one experiment, a long-term improvement in reproductive performance in cows was observed when early weaning was done when the females were first-calf heifers, he reports.
He explains that removal of calves reduces the nutritional requirements of first-calf heifers by eliminating the energy demand from lactation. In addition, since suckling has an inherent negative effect on cyclicity after calving, females tend to begin cycling sooner if calves are weaned very early. Body weight and condition can also be added back to young cows during a time when forages are more readily available.
Ahola acknowledges that there are several increased costs associated with early weaning, including:
1. facilities to handle early-weaned calves;
2. labor to manage younger calves; and
3. a feeding program to maintain optimum calf performance and health from the time of early weaning until they are sold.
Thus, he says, this is a decision that will need to be evaluated by each individual beef operation.