PRELIMINARY RESULTS REGARDING ESTRUS SYNCHRONIZATION IN POSTPARTUM DAIRY COWS WITH GnRH ANALOGUE, PRID – INTRAVAGINAL DEVICE AND PGF2 α, FOLLOWED BY ARTIFICIAL INSEMINATION AT ESTRUS DETECTION

Elena Ruginosu, Şt. Creangă, L. Dascălu, Mădălina-Alexandra Davidescu, Ioana-Cristina Crivei, Cătălina Sănduleanu, S.-I. Borş

Abstract
    This research was carried out within a dairy farm from North Eastern of Romania, on an experimental group (group E, n = 43) and control group (group C, n = 50 cows) from Romanian Black Spotted Breed (Friesian origin).
    The aim of study was to establish the efficiency of hormonal treatments applied to dairy cattle (group E) for estrus synchronization, consisting in: GnRH analogue (2.5ml Receptal) on day 0 (day of beginning treatment) and the insertion of an intravaginal device with progesterone (PRID Delta) for 7 days, prostaglandin F2α (2 ml Estrumate) on day 6 and artificial insemination at estrus detected. The treatments applied to the experimental group were performed between November 2017 and July 2018, the mean calving to treatment interval for experimental group being 49 days.
    The obtained results were represented by 90.7% inseminated cows from group E (n = 39); the treatment to first service interval (mean ± standard deviation) was 22.77 ± 3.95 days; treatment to conception interval (mean ± standard deviation) was 44 ± 7.99 days. We found in group E compared with group C the mean calving to first service interval with 18.53 days lower (79.6 ± 4.2 days vs. 98.13 ± 7.12 days); mean value of calving to conception interval with 43.03 day lower (98.9 ± 8.2 days vs. 141.16 ± 9.72 days) and the conception rate at first service with 8.8% higher (30.8% vs. 22.0%).
    In conclusion, the hormonal treatment protocol in dairy cattle estrus synchronization consisting a GnRH analogue (Receptal 2.5ml) in day 0, intravaginal progesterone device (PRID) for 7 days and PGF2α on day 6, can improve calving to first service interval, calving to conception interval and conception rate at first service being recommend it like a good alternative for improving reproduction.

Key words: dairy cattle, estrus synchronization, GnRH, PRID, Prostaglandin F2α