Abstract

MOZAFFARI, Sirous  and  GOLI, Mojtaba. Effect of the administration route of gonadotropin releasing hormone on the reproductive performance of multiparous Holstein cows. Veterinaria México OA [online]. 2022, vol.9, e986.  Epub May 29, 2023. ISSN 2448-6760.  https://doi.org/10.22201/fmvz.24486760e.2022.986.

We investigated the effect of epidural versus intramuscular administration of alarelin acetate (GnRHa; 25 ug) at artificial insemination (AI; day 0) and/or 7 days after AI on the pregnancy rate (PR) of Holstein cows that exhibited estrus spontaneously after their voluntary wait period. Cows (n = 117) were randomly allocated to treatment and control groups. In groups IM0, IM7, and IM07 (n = 12 per group), cows received GnRHa intramuscularly (IM) at 0 or 7 days, or both, respectively. In groups EP0 (n = 19), EP7 (n = 13) and EP07 (n = 11), cows received GnRHa at the sacrococcygeal epidural site (EP) at 0 or 7 days, or both, respectively. Animals in the control group (CON) received 5 mL of normal saline at 0 and 7 days. Pregnancy diagnosis was performed by rectal palpation of the uterine horns 60 days post AI. Results showed a significant difference in PR/first AI between IM0 and EP7 groups (16.67% vs. 61.54%; P < 0.05). Moreover, the results showed no significant differences in overall PR after two rounds of inseminations among all groups 60 days after the second AI. In conclusion, epidural injection of GnRHa 7 days after AI versus its intramuscular injection at AI improved PR/first AI significantly in Holstein lactating cows.

Keywords : artificial insemination; epidural administration; GnRH; Holstein cows; pregnancy rate; spontaneous estrus.

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