Fertility following synchronization of oestrus in Romney, Corriedale and Merino ewes.

Abstract

Abstract Extract Synchronization of oestrus in sheep has been achieved by the use of progesterone and progesterone analogues administered either as an intramuscular injection, or by an impregnated sponge inserted into the the vagina (Robinson, 1958 Robinson, T. J. 1958. Studies in controlled artificial insemination of Merino sheep. Aust. J. agric. Res., 9: 693–703. [Google Scholar], 1961 Robinson, T. J. 1961. The time of ovulation and efficiency. of fertilization following progesterone and pregnant mare serum treatment in the cyclic ewe. J. agric. Sci., Camb, 57: 129–135. [Google Scholar], 1964 Robinson, T. J. 1964. Synchronisation of oestrus in sheep by intravaginal and subcutaneous application of progestin impregnated sponges. Proc. Aust. Soc. anim. Prod., 5: 47–52. [Google Scholar]; Denny and Hunter, 1958 Denny, J. F. and Hunter, G. L. 1958. Synchronisation of the oestrus cycle in sheep. S. Afr. J. agric. Sci, 1: 381–388. [Google Scholar]; Brunner et al., 1964 Brunner, M. A., Hansel, W. and Hogue, D. E. 1964. Use of 6-methyl-17-acetoxyprogesterone and pregnant mare serum to induce and synchronise oestrus in ewes. J. anim. Sci., 23: 32–36. [Google Scholar]; Clark et al., 1966 Clark, J. N., Roberts, E. M., Carter, A. H. and Kirton, A. H. 1966. Hormonal synchronisation of oestrus in Romney Marsh ewes during the breeding season. Proc. N.Z. Soc. anim. Prod., 26: 107–121. [Google Scholar]). Twenty milligrams of progesterone administered every second day appears as effective as 10 mg daily (Robinson, 1958 Robinson, T. J. 1958. Studies in controlled artificial insemination of Merino sheep. Aust. J. agric. Res., 9: 693–703. [Google Scholar]) and provides satisfactory synchronization and fertility to natural service (Lamond and Bindon, 1962 Lamond, D. R. and Bindon, B. M. 1962. Oestrus, ovulation and fertility following suppression of ovarian cycles in Merino ewes by progesterone. J. Reprod. Fertil., 4: 57–66. [Google Scholar]).