Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-11-23T06:53:58.499Z Has data issue: false hasContentIssue false
  • English
  • Français

Annual reproductive rhythm and ovulation rate in four fat-tailed sheep breeds

Published online by Cambridge University Press:  02 September 2010

N. Sefidbakht ,
M. S. Mostafavi  and
A. Farid
N. Sefidbakht
Affiliation:
Department of Animal Science, College of Agriculture, Pahlavi University, Shiraz, Iran
M. S. Mostafavi
Affiliation:
Department of Animal Science, College of Agriculture, Pahlavi University, Shiraz, Iran
A. Farid
Affiliation:
Department of Animal Science, College of Agriculture, Pahlavi University, Shiraz, Iran
Get access

Abstract

Karakul, Mehraban, Naeini and Bakhtiari sheep were checked twice a day for oestrus using aproned rams and were laparotomized within 5 to 16 h of the end of every second oestrous period. Oestrus was observed for 12 monthly periods commencing on 21 April.

The Mehraban breed with 1 -6 oestrous periods per month was less seasonal in its breeding activity (P<0·01) than the other breeds. Four-year-old ewes were more sexually active (P<0·01) than 3-year-old ewes (1·48 v. 1·28 oestrous periods per month). Seasonal variation in the sexual activity of the ewes was observed (P<001); the peak of activity in July to January was followed by a steady decline in February and March to a low in April and May, and then a steep recovery phase in June. There was only limited sexual activity for at least 4 months (March to June).

The overall mean cycle length was 17·8 days (14 to 23 days), and the means for the four breeds were 17·6, 17·8, 17·8 and 17·9. The oestrous cycle was longer (P<0·05) during the period from December t o February than during that from June to August.

The overall mean duration of the oestrous period was 36·9 h and the means for the four breeds were 35·2, 38·0, 37·4 and 37·1 h, respectively (P<0·05). The duration showed some monthly variation (P<0·01) but did not follow a special seasonal pattern. The ovulation rates for the four breeds were 1·07, 1·13,0·94 and 0·95 respectively, (P<0·01). There was a non-significant decline in the mean ovulation rate from March to June. Right ovaries were more active than left ovaries as judged by the observation of a higher average number of corpora lutea per ewe per laparotomy (0·58 v. 0·43, P<001).

Type
Research Article
Information
Animal Production , Volume 26 , Issue 2 , April 1978 , pp. 177 - 184
Copyright
Copyright © British Society of Animal Science 1978

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

Amir, D. and Volcani, R. 1965. The sexual season of the Awassi fat-tailed ewe. J. agric. Sci., Camb. 64: 83–85.CrossRefGoogle Scholar
Bradford, G. E., Quirke, J. F. and Hart, R. 1971. Natural an d induced ovulation rate of Finnish Landrace and other breeds of sheep. Anim. Prod. 13: 627–635.Google Scholar
Casida, L. E., Woody, C. O. and Pope, A. L. 1966. Inequality in function of the right and left ovaries and uterine horns of the ewe. J. Anim. Sci. 25: 1169–1171.CrossRefGoogle ScholarPubMed
Dermody, W.C., Foote, W. C. and Hulet, C. V. 1966. Effects of season of year and progesterone synchronization on ovulation rate. J. Anim. Sci. 25: 585 (Abstr.).Google Scholar
Donald, H. P. and Read, J. L. 1967. The performance of Finnish Landrace sheep in Britain. Anim. Prod. 9: 471–476.Google Scholar
Dun, R. B., Waheed, Ahmed and Morrant, A. J. 1960. Annual reproductive rhythm in Merino sheep related to the choice of a mating time at Trangie, central western New South Wales. Aust. J. agric. Res. 11: 805–826.CrossRefGoogle Scholar
Emady, M., Noakes, D. E. and Arthur, G. H. 1975. Analysis of reproductive function of the ewe based on post mortem examination. Vet. Rec. 96: 261–266.CrossRefGoogle ScholarPubMed
Farid, A. and Makarechian, M. 1976. Some sources of variation in the body weights of Karakul, Mehraban, Naeini and Bakhtiari breeds of sheep. Iran J. agric. Res. 4: 7–16.Google Scholar
Hafez, E. S. E. 1952. Studies on the breeding season and reproduction of ewes. J. agric. Sci., Camb. 42: 189–265.CrossRefGoogle Scholar
Harvey, W. R. 1960. Least squares analysis of data with unequal numbers. United States Department of Agriculture, ARS–20–18.Google Scholar
Harvey, W. R. 1970. Estimation of variance and covariance components in the mixed model. Biometrics 26: 485–504.CrossRefGoogle Scholar
Hulet, C. V. and Foote, W. C. 1968. A rapid technique for observing the reproductive tract of living ewes. J. Anim. Sci. 27: 142–145.CrossRefGoogle ScholarPubMed
Joubert, D. M. 1962. Sex behaviour of purebred and crossbred Merino and Blackhead Persian ewes. J. Reprod. Fert. 3: 41–49.CrossRefGoogle ScholarPubMed
Kammlade, W. G., Welch, J. A., Nalbandov, A. V. and Norton, H. W. 1952. Pituitary activity of sheep in relation to the breeding season. J. Anim. Sci. 11: 646–655.CrossRefGoogle Scholar
Lamond, D. R. 1964. Seasonal changes in the occurrence of oestrus following progesterone suppression of ovarian function in the Merino ewe. J. Reprod. Fert. 8: 101–114.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. Endocr. 58: 305–317.CrossRefGoogle ScholarPubMed
McKenzie, F. F. and Terrill, C. E. 1937. Ovulation and related phenomena in the ewe. Res. Bull. Mo agric. Exp. Stn, No. 264.Google Scholar
Noorshadi, S., Bennett, J. A. and Bunch, T. D. 1975. Estrus and ovulation in fat tailed sheep. J. Anim. Sci. 41: 282 (Abstr.).Google Scholar
Radford, H. M. and Watson, R. H. 1957. Influence of rams on ovarian activity and oestrus in Merino ewes in the spring and early summer. Aust. J. agric. Res. 8: 460–470.CrossRefGoogle Scholar
Shelton, M. and Morrow, J. T. 1965. Effect of season on reproduction of Rambouillet ewes. J. Anim. Sci. 24: 795–799.CrossRefGoogle Scholar
Taleghani, H., Bunch, T. D., Bennett, J. A. and Foote, W. C. 1974. Estrous cycles in four fat-tailed breeds of sheep. J. Anim. Sci. 39: 165 (Abstr.).Google Scholar