Hostname: page-component-78c5997874-4rdpn Total loading time: 0 Render date: 2024-11-04T19:12:18.697Z Has data issue: false hasContentIssue false
  • English
  • Français

Effects of treatment with melatonin on the response of seasonally anovular ewes to the introduction of rams

Published online by Cambridge University Press:  02 September 2010

M. Rekik ,
M. J. Bryant  and
F. J. Cunningham
M. Rekik
Affiliation:
Department of Agriculture
M. J. Bryant
Affiliation:
Department of Agriculture
F. J. Cunningham
Affiliation:
Department of Biochemistry and Physiology, University of Reading, Reading RG6 2AT
Get access

Abstract

Sixty-four mature ewes (equal numbers of Bluefaced Leicester ♂ × Swaledale ♀ and Suffolk ♂ × (Bluefaced Leicester ♂ × Swaledale ♀) which had lambed in March were separated from their lambs on 1 fune. They were randomly allocated from breed and live-weight blocks to one of four treatments arranged in a 2 × 2 factorial design. All received vaginal implants, with or without melatonin, on 1 June. The implants were removed, all ewes given 20 mg progesterone in oil intramuscularly and equal numbers isolated or introduced to rams on 12 July. Ovarian activity was monitored by progesterone concentrations in blood taken three times weekly from the jugular vein. Four ewes receiving melatonin and four control ewes were bled for 24 h on 6 July to determine plasma melatonin concentrations.

Melatonin treatment increased plasma melatonin concentrations during the day. All ewes were anovular prior to 12 July. There were no differences between the two ewe types in their response to treatment. The number of ewes ovulating before 27 August was: control 1; melatonin 6; ram 16; melatonin + ram 16. The mean date of emulation for both the ram and melatonin + ram groups was 21 July. The number of ewes showing oestrous behaviour was 16 and 15 for the ram and melatonin + ram treatments respectively. The proportion of ewes responding to ram introduction was judged as unusually high, possibly as a result of the favourable male:female ratio. Pregnancy rate was in excess of 80% for both treatments, with resulting litter sizes of 14 for the ram and 1·8 for the melatonin + ram treatments respectively (P > 0·05).

Keywords

ewesmelatoninovulationrams
Type
Research Article
Information
Animal Production , Volume 53 , Issue 2 , October 1991 , pp. 203 - 207
Copyright
Copyright © British Society of Animal Science 1991

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Arendt, J., Symons, A. M. and Laud, C. A. 1981. Pineal function in the sheep: evidence for a possible mechanism mediating seasonal reproductive activity. Experientia 37: 584–586.CrossRefGoogle ScholarPubMed
Arendt, J., Symons, A. M., Laud, C. A. and Pryde, S. J. 1983. Melatonin can induce early onset of the breeding season in ewes. Journal of Endocrinology 97: 395–400.CrossRefGoogle ScholarPubMed
Bittman, E. L. and Karsch, F. J. 1984. Nightly duration of pineal melatonin secretion determines the reproductive response to inhibitory daylength in the ewe. Biology of Reproduction 30: 585–593.CrossRefGoogle Scholar
Brown, G. M., Grotta, L. J., Pulido, O., Burns, T. J., Nilis, N. L. and Snieckus, V. 1983. Application of immunologic techniques to the study of pineal indolalkylamines. Pineal Research Reviews 1: 1–246.Google Scholar
Haresign, W., Peters, A. R. and Staples, L. D. 1990. The effect of melatonin implants on breeding activity and litter size in commercial sheep flocks in the UK. Animal Production 50: 111–121.Google Scholar
Holdsworth, R. J. 1980. Measurement of progesterone in bovine plasma and preserved whole blood samples by a direct radioimmunoassay. British Veterinary journal 136: 135–140.CrossRefGoogle ScholarPubMed
Kennaway, D. J., Dunstan, E. A. and Staples, L. D. 1987. Photoperiodic control of the onset of breeding activity and fecundity in ewes. Journal of Reproduction and Fertility, suppl. no. 34, pp. 187–199.Google Scholar
Kennaway, D. J., Gilmore, T. A. and Seamark, R. F. 1982. Effect of melatonin feeding on serum prolactin and gonadotrophin levels and the onset of seasonal oestrous cyclicity in sheep. Endocrinology 110: 1766–1772.CrossRefGoogle Scholar
Lincoln, G. A. and Ebling, F. J. P. 1985. Effect of constantrelease implants of melatonin on seasonal cycles in reproduction, prolactin secretion and moulting in rams. Journal of Reproduction and Fertility 73: 241–253.CrossRefGoogle ScholarPubMed
Martin, G. B., Oldham, C. M., Cognie, Y. and Pearce, D. T. 1986. The physiological response of anovulatory ewes to the introduction of rams – a review. Livestock Production Science 15: 219–247.CrossRefGoogle Scholar
Nowak, R. and Rodway, R. G. 1985. Effect of intravaginal implants of melatonin on the onset of ovarian activity in adult and prepubertal ewes. Journal of Reproduction and Fertility 74: 287–293.CrossRefGoogle ScholarPubMed
Pearce, D. T., Martin, G. B. and Oldham, C. M. 1985. Corpora lutea with a short life-span induced by rams in seasonally anovulatory ewes are prevented by progesterone delaying the preovulatory surge of LH. Journal of Reproduction and Fertility 75: 79–84.CrossRefGoogle Scholar
Poulton, A. L., Brown, D. C., Thomas, E. M., Kelly, M. I., Symons, A. M. and Arendt, J. 1988. Use of an intraruminal soluble glass bolus containing melatonin for early lamb production. Veterinary Record 122: 226–228.CrossRefGoogle ScholarPubMed
Rajkumar, R. R., Argo, C. M., McNeil, M. E., Graham, N. B. and Rodway, R. G. 1988. Advancement of the breeding season in ewes given slow-release hydrogel melatonin implants. Society for the Study of Fertility, annual conference, Edinburgh, Abstr. 82.Google Scholar
Rekik, M, Bryant, M. J. and Cunningham, F. J. 1988a. The effect of pre-treatment with progesteron upon the response of seasonally anovular ewes to the introduction of rams. Animal Production 46: 511 (Abstr.).Google Scholar
Rekik, M., Bryant, M. J. and Cunningham, F. J. 1988b. A comparison of the effects of ram introduction and treatment with melatonin upon the breeding activity of seasonally anovular ewes. Animal Production 46: 510–511 (Abstr.).Google Scholar
Robinson, J. J., Aitken, R., Atkinson, T. and Fraser, C. 1985. The effects of oral administration of melatonin and/or exposure to a vasectomized ram on ovarian activity in ewes. Animal Production 40: 524 (Abstr.).Google Scholar
Sauer, M. J., Foulkes, J. A., Worsfold, A. and Morris, B. A. 1986. Use of progesterone ll-glucuronide-alkaline phosphatase conjugate in a sensitive microtitre-plate enzyme immunoassay of progesterone in milk and its application to pregnancy testing in dairy cattle. Journal of Reproduction and Fertility 76: 375–391.CrossRefGoogle Scholar
Signoret, J. P., Fulkerson, W. J. and Lindsay, D. R. 1982. Effectiveness of testosterone-treated wethers and ewes as teasers. Applied Animal Ethology 9: 37–45.CrossRefGoogle Scholar
Wigzell, S., Robinson, J. J., Aitken, R. P. and McKelvey, W. A. C. 1986. The effect of the oral administration of melatonin at two times of the year on ovarian activity in ewes. Animal Production 42: 448–449 (Abstr.).Google Scholar