Pospartum Anestrus and Puberty
FORT COLLINS (Dec. 2, 2008) — Anestrus is the absence of estrus, or those coordinated physiological events necessary for conception and the establishment of pregnancy. According to Colorado State University Beef Specialist Jack Whittier, anestrus among yearling heifers and postpartum cows often contributes to reduced reproductive efficiency in beef breeding herds.
Anestrus is the primary factor reducing reproductive efficiency in beef cow-calf operations, said Jack Whittier, Extension beef specialist at Colorado State University. Whittier discussed factors contributing to infertility and puberty in beef cattle herds.
“However, anestrus is one contributor to herd infertility with potential for manipulation through management,” Whittier told attendees of the Robert E. Taylor Memorial Symposium: Applied Reproductive Strategies in Beef Cattle Dec. 2 in Fort Collins, Colo.
The goal when developing replacement heifers, Whittier said, should be to ensure that a majority of heifers attain puberty at least one estrous cycle length prior to breeding season. Research data indicates that maturation of the reproductive system in heifers is heavily dependent on nutrition, including nutrient intake between 4 and 6.5 months of age. There is mounting evidence that the dam’s nutritional status during gestation also has a fetal programming effect on her heifer calf’s fertility. Progesterone therapy and biostimulation by the male also show promise for hastening puberty in heifers.
Whittier called postpartum anestrus the single most important reason why mature cows fail to rebreed during defined breeding seasons. Postpartum anestrus in cows also is heavily influenced by nutritional status. To minimize the length of the anestrus period, cows should exhibit a body condition score (BCS) of 5 or greater.
While it is not fully understood, the presence of a suckling calf may also inhibit a cow’s return to normal cycling behavior, Whittier noted. Removal of the calf for 48 hours is a practice that has been relatively effective in prompting a return to estrus. The presence of a bull or androgen-treated cow and the associated pheromone effect can also aid in shortening the period of anestrus. This “biostimulation” has also been used successfully, when introduced at least 45 days postcalving, to reduce the length of the anestrus period.
“This raises the question of whether putting a bull with cows at the start of the breeding season can have the same effect,” Whittier added. “There is no definitive proof, but I believe it does.”
The Robert E. Taylor Memorial Symposium is conducted by Colorado State University every other year to provide current, research-based information for improving profitability in the beef cattle industry. The ARSBC program was developed by the Beef Cattle Reproduction Task Force to improve understanding and application of reproductive technologies, including AI, estrus synchronization and factors affecting male fertility. In 2008, CSU and the Task Force collaborated to provide the Dec. 2-3 symposium in Fort Collins. To listen to Whittier’s presentation, view the accompanying PowerPoint or view other presentations from the symposium, visit the newsroom at www.appliedreprostrategies.com.
— by Troy Smith
Editor’s Note: This article is available as a news release to redistribute per an agreement between the symposium hosts and Angus Productions Inc. Click here to submit a request for a high-resolution photo of the speaker. For additional information visit the newsroom of www.appliedreprostrategies.com.