Changing the route of GnRH administration according to the initial cyclic phase of the Ovsynch protocol may optimize reproductive outcomes in dairy cows.

BACKGROUND: This study aimed to investigate the effects and interactions of gonadotropin-releasing hormone (GnRH) analogues (lecirelin and buserelin), administration routes (intramuscular and epidural), and initial estrus cycle phases (follicular and luteal) on fertility outcomes in cyclic dairy cows subjected to the Ovsynch protocol. RESULTS: concentrations on D13 (P < 0.001). CONCLUSION: Consequently, although changing the GnRH analogue and administration route did not significantly affect overall fertility outcomes, the findings suggest a possible phase-dependent relationship between administration route and pregnancy outcome. However, this trend requires confirmation in further studies.