Effects of Rams and Luteal or Follicular Phase Ewes on Preovulatory LH Surge Characteristics in Ewes

Authors : Sedat YILDIZ, Metehan UZUN, Mehmet KAYA

Pages : 669-673

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :This study aimed to investigate whether the preovulatory LH surge mechanism is involved in sheep-to-sheep interaction for oestrous synchronisation. For that purpose, anoestrous ewes were inserted with intravaginal progestagen sponges for 13 days to induce ovulation. Upon sponge withdrawal, they were introduced either to 4 rams insert ignore into journalissuearticles values(n = 6, ram group);, or to 4 ewes which were in follicular period insert ignore into journalissuearticles values(n = 6, follicular group);, or 4 ewes which were in the luteal period insert ignore into journalissuearticles values(n = 6, luteal group); or else they were kept alone insert ignore into journalissuearticles values(n = 6, control group);. The ewes were weighed and their body conditions were scored prior to the experiment. There were no significant differences in the body weights and body condition scores of the 4 groups. Blood samples were collected at 2 h intervals from sponge withdrawal insert ignore into journalissuearticles values(0 h); until the 96th h, and twice daily thereafter for 10 days. LH analyses were carried out on blood samples. According to data from the analyses, no LH surge was observed in the follicular and luteal groups within the 96 h following sponge withdrawal. The periods for observation of an LH surge were 162.7 ± 46.2, 224.0 ± 21.5, 58.7 ± 4.6 and 69.7 ± 6.7 h for the luteal, follicular, ram and control groups, respectively insert ignore into journalissuearticles values(P < 0.001);. Although no significant difference was observed between the ram and control groups, the LH surge in these groups occurred significantly earlier than those of the luteal insert ignore into journalissuearticles values(P < 0.05 and P = 0.075, respectively); and follicular insert ignore into journalissuearticles values(P < 0.001 for both groups); groups. In conclusion, it appears that female sheep delay the LH surges compared to the ram-introduced or control groups and that female-to-female interaction seems to suppress preovulatory LH surge generation centres.
Keywords : LH surge, pheromones, preovulatory, sheep to sheep interaction