PSXIII-1 Relationship between estrus expression detected by four methods and initial GnRH treatment with pregnancy per artificial insemination in suckler cows.

摘要

Twenty-nine cows with suckling calves were used to compare the effectiveness of four estrus detection methods, and to determine the relationship between estrus detection and initial GnRH treatment with pregnancy per artificial insemination. On day 115 postpartum, a 12-d Ov-Synch plus PRID ALPHA (device 1.55 g progesterone) protocol was used to synchronize cows for artificial insemination on day 14. Estrus detection methods were: i) visual observation (scoring signs of primary and secondary estrus behavior); ii) ESTROTECT mount-activated scratch-off device; iii) ALPRO activity meter; iv) plasma progesterone (Progesterone analysis indicated that all cows were in ovarian follicular phase on the insemination day, except for two cows that had lost the PRID and were not synchronized. Progesterone was taken as gold standard for synchronization. Estrus visual detection by scoring was the most effective method, with none false positive, whereas ESTROTECT and ALPRO showed 41 and 38% of false positives, respectively (P® were highly correlated. However, ALPRO method did not obtain a good correlation with the other methods, possibly influenced by cow management in the routine farm labor. A negative effect of excessive body condition on pregnancy rate was observed. In summary, estrus visual observation, omission of initial GnRH and non-excessive reserves were associated to greater pregnancy rates in suckler cows.