Hostname: page-component-848d4c4894-wg55d Total loading time: 0 Render date: 2024-05-16T22:23:56.731Z Has data issue: false hasContentIssue false
  • English
  • Français

Photoperiodism in the ewe. 3. The effects of various patterns of increasing daylength on the onset of anoestrus in Clun Forest ewes

Published online by Cambridge University Press:  02 September 2010

M. J. Ducker  and
J. C. Bowman
M. J. Ducker
Affiliation:
Department of Agriculture, The University of Reading, Berkshire
J. C. Bowman
Affiliation:
Department of Agriculture, The University of Reading, Berkshire
Get access

Summary

In light-proofed buildings experiments were conducted with six groups each of ten Clun Forest ewes to determine whether the onset of anoestrus was affected by the absolute size of increase in the case of an abrupt increase in daylength, and by the rate of increase in the case of a given total increase in daylength. The mean number of days from the onset of the light treatments to the cessation of oestrus (the reaction interval) for ewes receiving gradual increases in daylength of 3·5, 7·2 or 10·9 min per day from 23 December were 79·8, 84·1 and 75·7 days respectively. The reaction interval for ewes receiving abrupt increases in daylength of 3·75, 7·75 or 11·75 hr on 23 December were 86·3, 76·5 and 61·5 days respectively. A control group of ten ewes at pasture on natural daylength had a reaction interval of 93·6 days.

The results show that increasing daylength largely controls the mean date of onset of aneostrus in Clun Forest ewes. The greater the increase in daylength the sooner the onset of anoestrus occurs.

The observations on vaginal smears indicate that photoperiodic changes, whilst affecting the oestrous status of the ewe, may have no effect on ovulation.

Type
Research Article
Information
Animal Production , Volume 12 , Issue 3 , August 1970 , pp. 465 - 471
Copyright
Copyright © British Society of Animal Science 1970

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

REFERENCES

Allen, D. M. 1959. Some factors affecting fertility in female sheep. Ph.D. Thesis, Univ. Nottingham.Google Scholar
Ducker, M. J., Thwaites, C. J. and Bowman, J. C. 1970a. Photoperiodism in the ewe. 1. The effect of long supplemented daylengths on the breeding activity of pregnant and non-pregnant Teeswater-Clun ewes. Anim. Prod. 12: 107–113.Google Scholar
Ducker, M. J., Thwaites, C. J. and Bowman, J. C. 1970b. Photoperiodism in the ewe. 2. The effects of various patterns of decreasing daylength on the onset of oestrus in Clun Forest ewes. Anim. Prod. 12: 115–123.Google Scholar
Hafez, E. S. E. 1952. Studies on the breeding season and reproduction of the ewe. J. agric. Sci., Camb. 42: 189–265.CrossRefGoogle Scholar
Lees, J. L. 1967. Effect of time of shearing on the onset of breeding activity in the ewe. Nature, Lond. 214: 743.Google Scholar
Mauleon, P. and Rougeot, J. 1962. Regulation des saisons sexuelles chez des brebis de races differentes au moyen de divers rythmes lumineux. Annls Biol. anim. Biochim. Biophys. 2: 209–222.CrossRefGoogle Scholar
Radford, H. H. 1959. Variations in the incidence of twin ovulation in Merino ewes on a constant plane of nutrition. Aust. J. agric. Res. 10: 377–386.Google Scholar
Radford, H. H., Watson, R. H. and Wood, G. F. 1960. A crayon and associated harness for the detection of mating under field conditions. Aust. vet. J. 36: 57–66.Google Scholar
Thwaites, C. J. 1965. Photoperiodic control of breeding activity in the Southdown ewe with particular reference to the effects of an equatorial light regime. J. agric. Sci., Camb. 65: 57–64.Google Scholar
Wiggan, L. S. 1967. Studies on fertility in sheep with special reference to artificial insemination and control of ovarian cycles. Ph.D. Thesis, Univ. London.Google Scholar
Wodzicka-Tomaszewska, M., Hutchtnson, J. C. D. and Bennett, N. W. 1967. Control of the annual rhythm of breeding ewes: The effect of an equatorial daylength with reversed thermal seasons. J. agric. Sci., Camb. 68: 61–67.Google Scholar
Yeates, N. T. M. 1949. The breeding season of the sheep with particular reference to its modification by artificial means using light. J. agric. Sci., Camb. 39: 1–43.Google Scholar