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The effect of the oral administration of melatonin at two times of the year on ovarian activity in ewes

Published online by Cambridge University Press:  21 November 2017

S. Wigzell
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
J. J. Robinson
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
R. P. Aitken
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
W. A. C. McKelvey
Affiliation:
Rowett Research Institute, Bucksburn, Aberdeen AB2 9SB
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Extract

It has previously been shown (Robinson et al., 1985) that the normal breeding season of Greyface and Scottish Blackface ewes can be advanced by the daily administration of the indoleamine melatonin; the administration of the melatonin beginning midway during the anoestrous period. If melatonin is administered towards the end of the normal breeding season, oestrous activity can be extended, but only for a period of about six weeks until the ewe becomes refractory to the melatonin treatment (Nett and Niswender, 1981). There is no information on the administration of melatonin at the beginning of the anoestrous period.

In the following experiments we report results for the influence on the subsequent breeding activity of Greyface ewes of the oral administration of melatonin at the beginning of their normal period of anoestrus. We also report the results of an investigation on the effects of melatonin in advancing the breeding season of Scottish Blackface ewes maintained on either a high or low plane of nutrition. The experiments were carried out under natural daylength conditions at 57°N.

Type
Manipulation of Reproduction
Copyright
Copyright © The British Society of Animal Production 1986

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References

1. Robinson J.J., , Aitken, R.P., , Atkinson, T., and Fraser, C., (1985) Anim. Prod. 40, 524 (Abst.)Google Scholar
2. Nett, T.M. and Niswender, CD. (1982) Theriogenology 17, 645653.Google Scholar