Influence of estrogen in fertility of “problem" cows (repeat-breeding)

Abstract

The problem of repeat breeding was detected in 14% of a crossbred cattle herd of 333 cows in the State of Rio de Janeiro. The cows were on pasture and received a supplemental ration of concentrate during milking. Artificial insemination was used. An experiment with estrogenic hormone (2 mg) intravenously injected after insemination showed that 31 of 46 cows (67.4%) got pregnant with 68 total inseminations against 204 previous negative ones. The authors concluded that estrogenic hormone may increase fertility in repeat-breeders with a history of three or more inseminations without conception.