Induction of oestrus with norgestomet in acyclic post-pubertal holstein heifers

Cetin Y., Uslu B. A. , Gungor O., Sendag S.

BULLETIN OF THE VETERINARY INSTITUTE IN PULAWY, cilt.51, sa.2, ss.247-251, 2007 (SCI İndekslerine Giren Dergi) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 51 Konu: 2
  • Basım Tarihi: 2007
  • Sayfa Sayıları: ss.247-251


The study was carried out during April and May 2006, on thirty-eight 15 - 23-month-old Holstein heifers with inactive ovaries, which were selected from a private dairy herd with 300 heifers. The heifers were randomly distributed into two groups: norgestomet group (n=29), and a control group (n=9). In the norgestomet group, silicone ear implants containing 6 mg of norgestomet were implanted, and a solution containing 3 mg of norgestomet and 5 mg of oestradiol valerate was injected intramuscularly. The silicone implants were removed 11 d later, and the heifers were continuously observed for signs of oestrus for three days. The heifers were inseminated 48 and 78 h after the removal of the implants, and after the first insemination they were treated with 50 tg of GnRH analogue. The rate of the induced oestrus was 86.2% (25/29) and 0% (0/9) in norgestomet and control groups, respectively. The pregnancy rate was 48.2% (14/29) and 0% (0/9) in norgestomet and control groups, respectively. Our results showed that fertile oestrus can be stimulated successfully in post-pubertal heifers with inactive ovaries by a norgestomet treatment, and successful pregnancy rate can be obtained by a fixed-time insemination during this oestrus.