Efficiency of half-dosis of Cloprostenol subvulvar mucous inducing estrus and pregnant rate in cows “repeat breeders” Nelore-Chianina

Abstract

This study has the objective of evaluating the efficiency of a dose of 1 mL (250 ?g of cloprostenol) in the vulvar submucous, in the group 2 (G2) of 25 cows, in relation to an intramuscular dose of 2 mL (500 ?g of cloprostenol) formed by the group 1 (G1) of 24 cows ½ Nelore-Chianina, totaling 49 female repeatbreeders. The cows were with at least 120 days period post partum remaining in the reproductive season between December 2003 and February 2004. The application of cloprostenol was repeated eleven days after in the cows did not show estrus until 5 days of the first dose. The total percentage of estrus were of 79.16% (G1) and 56% (G2). The media of the hours for estrus being present was of 81.35 hours (first dose) and 92.8 hours (second dose) and 71.5 hours (first dose) and 76.1 hours (second dose) for G1 and G2 respectively. In relation to the media hours for the presence of estrus, in the groups G1 and G2 for first dose, second dose, and for the total number of cows in estrus, there were no significant difference (p>0.05). The artificial inseminations were performed 12 hours after the appearance of estrus and the gestation diagnostic at 53 days after the last insemination by means of rectal palpation confirmed by transrectal ultrasonography where 20 cows were diagnosed as gestating. Ten in the G1 and ten in the G2 totaling 40.8% gestating. The strategic application of cloprostenol is suggested for the cows repeatbreeders at the end of the reproductive season.