Cetin, YunusUslu, Baris A.Gungor, OrsanSendag, Sait2025-05-102025-05-1020070042-48702-s2.0-34547997097https://hdl.handle.net/20.500.14720/17674Cetin, Yunus/0000-0002-5402-9429; Uslu, Baris Atalay/0000-0003-1866-932XThe 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.eninfo:eu-repo/semantics/closedAccessHeiferOestrus SynchronisationInactive OvaryNorgestometArticle512N/AN/A247251WOS:000247794900012