Veterinary Archives, Vol. 94 No. 5, 2024.
Original scientific paper
https://doi.org/10.24099/vet.arhiv.1564
Reproductive performance improvement following the implementation of a modified Double-Ovsynch protocol compared to G6G in lactating Holstein cows
Hesam Kohsari
; Department of Veterinary, Agriculture Faculty, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
*
Khatereh Berenjian
; Shaghayegh Gharb Pakhsh Veterinary Pharmaceutical Company, Department of distribution, Kermanshah, Iran
Sohrab Heydarian
; Department of Veterinary, Agriculture Faculty, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
* Corresponding author.
Abstract
This study evaluated a new presynchronization method, the combination of Presynch and Ovsynch, prior to the implementation of the Ovsynch-fixed timed artificial insemination (OVS+FTAI) protocol, as modified by Double-Ovsynch (MDO) compared to the G6G protocol. Lactating Holstein cows in G6G (n=250) and MDO (n=270) treatment groups received the following treatments, respectively: PGF2α-2d-GnRH(pre-GnRH1)-6d-OVS+FTAI (GnRH(GnRH1)-7d-PGF2α(PG)-2d-GnRH(GnRH2)-18h-FTAI) and PGF2α-7d-GnRH-7d-PGF2α-3d-GnRH(pre-GnRH1)-7d-OVS+FTAI. On average, the days in milk (DIM) of cows at the time of GnRH1 injection was 75±0.08 (mean±SEM). Pregnancy was diagnosed 32-38 days after timed AI by ultrasonographic examination. Modified Double-Ovsynch increased the pregnancies per AI (P/AI) compared to the G6G protocol (P=0.01). For all cows (n=520), the pregnancy rate was higher in cows that had preovulatory follicles ≥16 mm in diameter at the time of GnRH2 injection, compared to the cows that had preovulatory follicles <16 mm in diameter at the same time (P=0.03). Modified Double-Ovsynch increased the mean (±SEM) serum concentration of progesterone (P4, ng/ml) at PG compared to the G6G protocol (P<0.01). Therefore, MDO increased the pregnancy rate of cows at the first postpartum insemination compared to the G6G protocol, due to the induction of ovulation in noncyclic cows, improvement of synchronization in ovarian events, improvement of the quality of the ovulatory follicles and oocytes, and provision of an appropriate intrauterine environment for embryonic development and survival.
Keywords
G6G; modified Double-Ovsynch; pregnancy; Holstein cows
Hrčak ID:
320606
URI
Publication date:
1.9.2024.
Visits: 0 *