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The aim of the present study was to evaluate the effect of various administration routes of PGF2α analogue, D-cloprostenol, at the time of artificial insemination (AI) on conception rate in a large dairy herd. A total number of 659 lactating dairy cows (101 heifers and 558 cows) were enrolled in the study. Following heat detection, the cows were artificially inseminated according to the AM-PM rule. The animals were divided into a control (29 heifers and178 cows) and three experimental groups; IM (53 heifers and 110 cows), IV (155 cows) and IU (19 heifers and115 cows) groups that received intramuscular 150 µg, intravenous 150 µg and intrauterine 5 µg of D-cloprostenol, respectively, at the time of AI. The control group did not receive any treatment at the time of AI. To measure serum progesterone concentration, blood samples were obtained from 15 cows in each group at the time of insemination and on days 4 and 15 post-insemination. Pregnancy was diagnosed by rectal ultrasound examination between days 35-40 post-insemination. The effects of treatments, parity, milk production, and days in milk (DIM) on conception rate of adult cows were evaluated using the multivariate logistic regression model. Intramuscular administration of D-cloprostenol at the time of AI significantly increased conception rate in dairy cows compared to the control group (60.1% vs. 40.6%; p = .005). However, intravenous and intrauterine administration of D-cloprostenol did not alter the conception rate (32.3%; p = .29 and 50%; p = .11, respectively). D-cloprostenol treatment at AI could not significantly increase the conception rate of heifers followingboth (IM & IU) administration routes. In conclusion, this study showed that intramuscular administration of D-cloprostenol at the time of insemination might improve the conception rate in adult cows, while its intravenous and intrauterine administration did not induce any positive effects on reproductive efficiency of dairy cows.HIGHLIGHTS Intramuscular administration of D-cloprostenol at the time of insemination might improve the conception rate in adult cows. Intravenous administration of D-cloprostenol did not induce any positive effects on reproductive efficiency of dairy cows. Intrauterine administration of D-cloprostenol did not induce any positive effects on conception rate of dairy cows. |
