Puberty and Anestrus: Dealing with Non-cycling Females

Achieving a consistently successful A.I.-breeding program in a cow-calf operation requires attention to those heifers and cows not having normal estrous cycles (cycling) at the beginning of the breeding season. Because so many factors contribute to whether breeding females are cycling, including weather patterns, nutrition (availability of native forages or stored feeds), age or days since calving, body condition, suckling intensity, and breed composition, to name a few, each breeding season is a challenge. A second challenge is matching the many products and programs available to synchronize estrus, ovulation, or both, to the needs of the breeding females and the objectives of the operation. Some programs will succeed in most operations when a large proportion of the breeding females are cycling at the onset of the breeding season. Other programs, which are sometimes more costly or more difficult to administer, are more successful when applied to females that are not cycling. The management challenge is to determine which program will best meet the needs of the breeding herd in any given year. Fortunately, due to some excellent research in recent years, a few programs have been identified that provide acceptable pregnancy rates in those herds that have larger proportions of non-cycling females than desired.