Hostname: page-component-586b7cd67f-tf8b9 Total loading time: 0 Render date: 2024-11-27T21:30:16.987Z Has data issue: false hasContentIssue false
  • English
  • Français

Seasonal variation in oestrus and ovarian activity of Finnish Landrace, Tasmanian Merino and Scottish Blackface ewes

Published online by Cambridge University Press:  02 September 2010

A. G. Wheeler  and
R. B. Land
A. G. Wheeler
Affiliation:
ARC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
R. B. Land
Affiliation:
ARC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
Get access

Summary

The patterns of seasonal variation in reproductive activity were observed over a period of 15 mo for approximately 15 females of each of three breeds: Finnish Landrace (Finn), Tasmanian Merino (Merino) and Scottish Blackface (Blackface). The incidence of oestrus was measured by teasing with vasectomized rams, and the incidence and rate of ovulation were determined frequently by laparoscopy. Luteal function was assessed from peripheral venous blood progesterone concentration on days 7 and 11 of the oestrous cycle. Nutritional status was monitored by recording body weight and plasma-free fatty acid levels throughout the study.

The breeding seasons differed significantly: Finn, October to May; Merino, September to February; and Blackface, October to February. Variation in the incidence of ovulation was similar to that in the incidence of oestrus for each breed. The incidence of silent ovulation varied with the breed, being greatest in the Merino and least in the Finn. The ovulation rate varied among breeds (Finn, 2·99; Merino, 1·08 and Blackface, 1·30), and during the breeding season (e.g. Finn: November, 3·5; March, 2·6). Follicles were observed in each breed throughout the period of study.

The pattern of variation in progesterone concentration was similar for each breed despite their different breeding seasons. In addition to breed differences in ovulation rate and in onset and end of the breeding season, the sensitivity to oestrogen was apparently such that, with the Finn if oestrogen secretion was high enough to stimulate ovulation it would usually also stimulate oestrus, whereas with the Merino ovulation often occurred without oestrus; this suggests that in the Merino the centres controlling ovulation are more sensitive to oestrogen than those controlling behaviour.

Type
Research Article
Information
Animal Production , Volume 24 , Issue 3 , June 1977 , pp. 363 - 376
Copyright
Copyright © British Society of Animal Science 1977

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

Hanrahan, J. P. and Quirke, J. F. 1975. Repeatability of the duration of oestrus and breed differences in the relationship between duration of oestrus and ovulation rate of sheep. J. Reprod. Fert. 45: 29–36.CrossRefGoogle ScholarPubMed
Kammlade, W. G. Jr, Welch, J. A., Nalbandov, A. V. and Norton, H. W. 1952. Pituitary activity of sheep in relation to the breeding season. J. Anim. Set 11: 646–655.Google Scholar
Kelley, R. B. 1946. Studies on the breeding performance of ewes. Bull. Coun. sclent. ind. Res., Melb., No. 205.Google Scholar
Lamond, D. R., Gaddy, R. G. and Kennedy, S. W. 1972. Influence of season and nutrition on luteal plasma progesterone in Rambouillet ewes. J. Anim. Set. 34: 626–629.CrossRefGoogle ScholarPubMed
Land, R. B., Pelletier, J., Thimonier, J. and Mauleon, P. 1973. A quantitative study of genetic differences in the incidence of oestrus, ovulation and plasma luteinizing hormone concentration in the sheep. J. Endroc. 58: 305–317.CrossRefGoogle ScholarPubMed
Land, R. B., Russell, W. S. and Donald, H. P. 1974. The litter size and fertility of Finnish Landrace and Tasmanian Merino sheep and their reciprocal crosses. Anim. Prod. 18: 265–271.Google Scholar
Land, R. B., Wheeler, A. G. and Carr, W. R. 1976. Seasonal variation in the oestrogen induced LH discharge of ovariectomised Finnish Landrace and Scottish Blackface ewes. Annls Biol. anim. Biochim. Biophys. 16: 521–528.CrossRefGoogle Scholar
Lees, J. L. 1971. Some aspects of reproductive efficiency in sheep. Vet. Rec. 88: 86–95.CrossRefGoogle ScholarPubMed
Patterson, D. S. P. 1963. Some observations on the estimation of non-esterified fatty acid concentrations in cow and sheep plasma. Res. vet. Sci. 4: 230–237.CrossRefGoogle Scholar
Quirke, J. F. and Gosling, J. 1975. Progesterone concentration in the peripheral plasma of Galway and Finnish Landrace sheep during the oestrous cycle. Ir. J. agric. Res. 14: 49–53.Google Scholar
Riches, J. H. and Watson, R. H. 1954. The influence of the introduction of rams on the incidence of oestrus in Merino ewes. Aust. J. agric. Res. 5: 141–147.CrossRefGoogle Scholar
Scaramuzzi, R. J., Corker, C. S., Young, G. and Baird, D. T. 1976. Production of antiserum to steroid hormones in sheep. In SteroidImmunoassay (ed. Cameron, E. H. D., Hillier, S. G. and Griffiths, K.), pp. 111–122. Alpha Omega Publishing, Cardiff.Google Scholar
Thimonier, J. and Mauleon, P. 1969. [Seasonal variations in oestrous behaviour and pituitary activities in the ewe.] Annls Biol. anim. Biochim. Biophys. 9: 233–250.CrossRefGoogle Scholar
Wiener, G. 1967. A comparison of the body size, fleece weight and maternal performance of five breeds of sheep kept in one environment. Anim. Prod. 9: 177–195.Google Scholar