Hostname: page-component-cd9895bd7-dk4vv Total loading time: 0 Render date: 2024-12-27T18:57:05.185Z Has data issue: false hasContentIssue false
  • English
  • Français

Ovulation rate of Lincoln ewes at Bahia Blanca, Argentina

Published online by Cambridge University Press:  02 September 2010

R. M. Rodriguez Iglesias ,
C. Giglioli ,
N. Latimori  and
H. Irazoqui
C. Giglioli
Affiliation:
Departamento de Agronomía, Universidad Nacional del Sur, Bahìa Blanca (8000), Argentina
N. Latimori
Affiliation:
Departamento de Agronomía, Universidad Nacional del Sur, Bahìa Blanca (8000), Argentina
H. Irazoqui
Affiliation:
Departamento de Agronomía, Universidad Nacional del Sur, Bahìa Blanca (8000), Argentina
Get access

Abstract

An experiment was carried out at Bahia Blanca (38°44' S, 62°10' W) to estimate the seasonal variation in ovulation rate and its components shown by Lincoln ewes of constant live weight.

Twenty-three 5-year-old ewes were subjected to nine 17-day observation periods which were evenly spaced within 405 days.

Percentage of ewes showing oestrus and ovulation, incidence of multiple ovulations and ovulation rate were estimated for each period by using vasectomized rams and performing iaparoscopies.

Traits showed a similar seasonality which was presumably induced by the natural light regime to which the ewes became exposed before and during each observation period.

A significant and periodic relationship was found between each trait and the number of days elapsed from the longest day.

The predicted maximum values for each parameter were reached about 40 days before the shortest day. Prior to and after this date both the percentage of ewes showing oestrus and ovulation and the incidence of multiple ovulations declined so that the expected ovulation rate values became zero for a period of about 3 months before the longest day.

Type
Research Article
Information
Animal Production , Volume 45 , Issue 3 , December 1987 , pp. 459 - 464
Copyright
Copyright © British Society of Animal Science 1987

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

Cogniè, Y. and Maulèon, P. 1983. Treatment of anoestrous ewes. In Sheep production (ed Haresign, W.), pp. 383–384. Butterworths, London.Google Scholar
Ducker, M. J. and Boyd, J. S. 1974. The effect of daylength and nutrition on the oestrous and ovulatory activity of Greyface ewes. Animal Production 18: 159–167.Google Scholar
Haresign, W., McLeod, B. J. and Webster, G. M. 1983. The potential for inducing out-of-season breeding in the ewe. In Sheep Production (ed. Haresign, W.). pp. 368–370. Butterworths, London.Google Scholar
Irazooui, H. and Menvielle, E. E. 1982. Ovulation rate of Corriedale ewes at Bahìa Blanca, Argentina. Animal Production 35: 313–320.Google Scholar
Little, T. M. and Jackson Hills, F. 1978. Agricultural Experimentation. Design and Analysis. John Wiley, New York.Google Scholar
Martin, G. B., Oldham, C. M. and Lindsay, D. R. 1980. Increased plasma LH levels in seasonally anovular Merino ewes following the introduction of rams. Animal Reproduction Science 3: 125–132.CrossRefGoogle Scholar
Scaramuzzi, R. J. and Martensz, N. D. 1975. Effects of active immunization against androstenedione on luteinizing hormone levels in the ewe. In Immunization with Hormones in Reproductive Research (ed. Nieschlag, E.), pp. 141. North Holland Publishing, Amsterdam.Google Scholar
Thimonier, J. and Maulèon, P. 1969. [Seasonal variations in oestrous behaviour and ovarian and pituitary activities in the ewe.] Annales de Biologie Animate, Biochimie et Biophysique 9: 233–250.CrossRefGoogle Scholar
Thimonier, J., Maulèon, P.Cogniè, Y. and Ortavant, R. 1968. [Induction of oestrus and pregnancy in the ewe during post partum anoestrus by means of pessaries impregnated with fluorogestone acetate.] Annales de Zootechnie 17: 257–273.CrossRefGoogle Scholar
United States Department of Agriculture. 1975. Soil taxonomy: a basic system of soil classification for making and interpreting soil surveys. Handbook, U.S. Department of Agriculture, No. 436.Google Scholar
Wheeler, A. G. and Land, R. B. 1977. Seasonal variation in oestrus and ovarian activity of Finnish Landrace, Tasmanian Merino and Scottish Blackface ewes. Animal Production 24: 363–376.Google Scholar