Effects of nutritional environment and ram effect on breeding season in range sheep

TitleEffects of nutritional environment and ram effect on breeding season in range sheep
Publication TypeJournal Article
Year of Publication1986
AuthorsHulet, Clarence V., Shupe, W. Larry, Ross T.T., Richards W.A.
JournalTheriogenology
Volume25
Pagination317-323
Date PublishedFebruary 1, 1986
Keywordsbreeding season, nutrition, ovulation, ram effect, range sheep
AbstractEffects of season, nutritional environment, and presence of rams on incidence and rate of ovulation in fine-wool sheep in southern New Mexico were investigated over 14 months (February 1983–March 1984). Number of corpora lutea (CL) were observed each month by laparoscopy in random samples from six ewes in each subgroup. Seasonality of ovulation in fine-wool sheep managed on range was much more marked than in animals managed on alfalfa hay in drylot. Incidence of ovulation approached zero in range-managed ewes during May, June, and July (8%, 0%, 4%) but was higher (P0.10) between nutrition groups within the 14 months. Body weight was related to CL number during periods of seasonal transition only. Continuous or intermittent presence of a ram had no real effect on either incidence or rate of ovulation during the transitional months. Nutritional environment can affect seasonality of breeding in fine-wool range sheep. This effect may not be consistently modified by presence of rams.
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