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A comparison between the effect of various photoperiods on the reproductive performance of Scottish Half-bred ewes

Published online by Cambridge University Press:  27 March 2009

J. E. Newton  and
J. E. Betts
J. E. Newton
Affiliation:
The Grassland Research Institute, Hurley, Maidenhead, Berkshire
J. E. Betts
Affiliation:
The Grassland Research Institute, Hurley, Maidenhead, Berkshire
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Summary

Four experiments are described in which attempts were made to increase the number of live lambs born per ewe per unit time. In the first experiment 22 Scottish Half-bred ewes were subjected to an artificial photoperiod. This resulted in 95 % of the ewes being mated 128 days after their previous lambing. It was estimated that artificial photoperiod brought the breeding season forward by about 5 weeks. The use of 1500 i.u. Pregnant Mare Serum had no significant effect on mean litter size. In the second experiment three artificial photoperiods were compared with natural daylength. In Group 2 photoperiod was decreased rapidly on 2 April from 18 to 10 h, in Group 3 photoperiod was decreased gradually on 2 April from 24 h and in Group 4 photoperiod was decreased rapidly on 28 May from 18 to 10 h. Group 5 was the control. Median intervals from parturition to next conception for Groups 2–5 were 70, 138, 68 and 131–5 days respectively; median intervals from onset of decreasing daylength to conception were 129, 200, 83 and 118–5 days respectively. Treatments 2 and 4 significantly reduced the interval from parturition to next conception but treatment 3 was unsuccessful. The interval from onset of decreasing daylength to conception was significantly shorter for treatment 4 than for treatment 2.

In Exp. 3 an unsuccessful attempt was made to extend the natural breeding season by preventing photoperiod from increasing for 3 months after 22 December.

In Exp. 4 a similar photoperiodic pattern was used for Groups 9 and 10 (16 h photoperiod decreasing rapidly to 8 h on 18 February). The contrast was that in Group 9 most of the ‘light’ was natural, in Group 10 all the ‘light’ was artificial. This pattern was compared with the natural daylength pattern (Group 8), an equinoctial treatment (Group 11) and a short-day treatment, 8h light, 16 h dark (Group 12). The median intervals from parturition to next conception for Groups 8–12 were 194, 102, 99, 156, 155 days, respectively. There was no significant difference in this interval between Groups 9 or 10. Type of ‘light’ therefore had no influence on the median interval from parturition to next conception; but photoperiodic pattern did. A rapid increase to 16 h light followed by a rapid decrease to 8 h (Groups 9, 10) was more effective than either the equinoctial treatment (Group 11) or the short-day treatment (Group 12). The treatments imposed on Groups 11 and 12 were more effective in shortening the median interval from parturition to next conception than the natural daylength pattern (Group 8). Time of year of mating had no effect on lambing percentage.

It was concluded that the sensitivity of sheep to photo-stimulation varied directly, with time from the onset of the next natural breeding season and with the speed of photoperiodic decrease.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 78 , Issue 3 , June 1972 , pp. 425 - 433
Copyright
Copyright © Cambridge University Press 1972

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References

REFERENCES

Betts, J. E., Newton, J. E. & Denehy, H. L. (1969). Out-of-soason breeding in sheep. Vet. Bee. 84, 358–9.Google ScholarPubMed
Ducker, M. J., Thwaites, C. J. & Bowman, J. C. (1970). 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, 115–23.Google Scholar
Dutt, R. H. & Bush, L. F. (1955). The effect of low environmental temperature on the initiation of the breeding season in sheep. J. Anim. Sci. 14, 885–96.Google Scholar
Edgar, D. G. & Bilkey, D. A. (1963). Influence of rams on the onset of the breeding season in ewes. Proc. N.Z. Soc. Anim. Prod. 23, 79.Google Scholar
Fraser, A. F. & Laing, A. H. (1969). Oestrus induction in ewes with standard treatments of reduced natural light. Vet. Bee. 84, 427–30.Google Scholar
Gordon, I. (1963). The induction of pregnancy in the anoestrous ewe by hormonal therapy. II. Progesterone-pregnant mare's serum applications in anoostrous. J. agric. Sci., Camb. 60, 43–66.CrossRefGoogle Scholar
Gorski, R. A. (1968). The neural control of ovulation. In Biology of Gestation (ed. Assali, N. S.), London and New York: Academic Press.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
Kruskal, W. H. (1952). A non-parametric test for the several sample problem. Ann. math. Statist. 23, 525–40.CrossRefGoogle Scholar
Large, R. V. (1970). The biological efficiency of meat production in sheep. Anim. Prod. 12, 393–401.Google Scholar
Mauleon, P. & Rougeot, J. (1962). Regulation des saisons sexuelles chez des brebis de races differentes au moyen de divers rhythmes lumineux. Annls Biol. anim. Biochim. Biophys. 2, 209–22.CrossRefGoogle Scholar
Newton, J. E. & Betts, J. E. (1967). Breeding performance of Dorset Horn ewes augmented by hormonal treatments. Expl Agric. 3, 307–13.Google Scholar
Newton, J. E., Betts, J. E. & Large, R. V. (1970). Increasing litter size in three breeds of sheep by superovulation. J. agric. Sci., Camb. 75, 355–60.CrossRefGoogle Scholar
Porter, W. P. & Gates, D. M. (1969). Thermodynamic equilibria of animals with environment. Ecol. Monogr. 39, 245–70.CrossRefGoogle Scholar
Radford, H. M. (1961). Photoperiodism and sexual activity in Merino ewes. Aust. J. agric. Res. 12, 139–53.Google Scholar
Sadleir, R. M. F. S. (1969). The Ecology of Reproduction in Wild and Domestic Mammals. London: Methuen.Google Scholar
Thibault, C., Courot, M., Martinet, L., Mauleon, P., du Mesnil du Buisson, F., Ortavant, R., Pelletier, J. & Signoret, J. P. (1966). Regulation of breeding season and estrous cycles by light and external stimuli in some mammals. J. Anim. Sci. 25, 119–42.Google Scholar
Thwaites, C. J. (1965). Photoperiodio 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
Williams, H. Ll. (1965). Three lamb crops in two years. Dairy Fmr, Ipswich 12, 46–8.Google Scholar
Williams, H. Ll. (1969). An assessment of the role of photo-stimulation in the modification of the breeding season of sheep. Anim. Prod. 11, 283–4.Google Scholar
Wodzicka-Tomaszewska, M., Hutchinson, J. C. D. & Bennett, J. W. (1967). Control of the annual rhythm of breeding in ewes: effect of an equatorial daylength with reversed thermal seasons. J. agric. Sci., Camb. 68, 61–7.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.CrossRefGoogle Scholar