Induced ovulation of the first postpartum dominant follicle in beef suckler cows using a GnRH analogue

There is a low incidence of ovulation of the first dominant follicle that develops in the early postpartum period of beef suckler cows, which prolongs the interval from calving to first ovulation. The objective of this study was to determine whether a single injection of a GnRH analogue would ovulate the first postpartum dominant follicle. Limousin×Friesian beef suckler cows were assigned at parturition, over two years (16 cows in year 1; 19 cows in year 2), to one of three treatments: (1) untreated (control; n=12), (2) GnRH analogue (20 μg buserelin i.m.) administered in the growing-plateau phase of the first postpartum dominant follicle (GnRH-G; n=12) and (3) GnRH analogue administered in the declining phase of the first postpartum dominant follicle (GnRH-D; n=11)