Effect of estrogen on fertility of apparently normal cows

Abstract

In these days of rapidly increasing production in dairy herds, fertility may become a problem. The authors studied the effect of estrogen on 136 apparently normal crossbred dairy cows, which comprised part of the IPEACS herd at Km 47 Rio-São Paulo Road, Itaguaí, State of Rio de Janeiro. These cows had produced one or more calves and were range managed but with suplementary ration during milking. Sixty-seven cows received 2 mg of hormone (intravenously) at the time of insemination and the others served as controls. Statistical analysis showed that the use of estrogen did not effect the fertility of the treated cows in relation to the controls. It was concluded that the administration of estrogen to apparently normal cows did not confirm the idea, that the hormone used at the first estrus following an interval after calving, could decrease the number of infertile inseminations.