Effects of maturity of the potential ovulatory follicle on induction of oestrus and ovulation in cattle with oestradiol benzoate

• Published in: Animal reproduction science 2001-05, Vol.66 (3), p.161-174
• Main Authors: Burke, C.R, Mussard, M.L, Grum, D.E, Day, M.L
• Format: Article
• Language: English
• Subjects: Administration, Intravaginal; Animals; Cattle; Cattle - physiology; Dinoprost - pharmacology; Estradiol - analogs & derivatives; Estradiol - pharmacology; Estrus - drug effects; Female; Follicle; Oestradiol benzoate; Oestrous synchronisation; Ovarian Follicle - anatomy & histology; Ovarian Follicle - physiology; Ovulation; Ovulation Induction; Progesterone - administration & dosage; Progesterone - blood
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/S0378-4320(01)00101-4

The effect of maturity of the dominant follicle (DF) on the capacity of oestradiol benzoate (ODB) to induce oestrus and ovulation was examined in cattle. In experiment 1, 31 prepubertal heifers each received an intravaginal progesterone insert (IPI) and 1 mg ODB i.m./500 kg BW (ODB1). Daily ovarian ultrasonography detected emergence of a new follicular wave 3.1±0.1 days after ODB1. The IPI was removed when newly emerged DF were “young” (1.3±0.1 days after emergence; YDF; n=15) or “mature” (4.2±0.1 days; MDF; n=16), and 24 h later, heifers received 0.75 mg ODB/500 kg BW (ODB2; n=16) or no further treatment (NoODB2; n=15). Most of the heifers receiving ODB2 were observed in oestrus (15/16) and ovulated (12/16), as compared to 0/15 and 1/15 in the NoODB2 group, respectively ( P