J. Anim Sci.
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J. Anim Sci. 1968. 27:1401-1403.
© 1968 American Society of Animal Science
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Effects of a Single Injection of Estrogen Early in the Estrous Cycle on Pituitary and Luteal Function in Ewes1

B. E. Howland2, R. L. Kirkpatrick3, C. O. Woody, A. L. Pope and L. E. Casida

University of Wisconsin, Madison

Abstract

Twenty-four mature ewes were studied to determine the effect of a single injection of estradiol–17β on pituitary and ovarian function. Twelve ewes received an intramuscular injection of 2 mg. of estradiol–17β the morning of day 5 and were killed the afternoon of day 7 (approximately 56 hr. later). Six untreated controls were killed on day 5 and six on day 7 of the estrous cycle. New ovulations were observed in eight of 12 treated ewes. Estrous behavior was induced in three of eight ewes which ovulated and one ewe that failed to ovulate. LH activity in pituitaries of estrogen treated ewes was significantly less than that observed for controls killed on the same day of the cycle, indicating an LH release which presumably led to the new ovulations. The total progesterone content of corpora lutea of estrogen treated ewes was significantly depressed by the treatment.

Footnotes

1 Paper No. 1181 from the Genetics Laboratory and No. 496 from the Department of Meat and Animal Science. Published with the approval of the Director of the Agricultural Experiment Station. This investigation was supported in part by a grant from the Ford Foundation and in part by Public Health Service Training Grant No. 1 T1 HD 104-01, from the National Institute of Child Health and Human Development.

2 Present address: Dept. of Oral Biology, Faculty of Dentistry, University of Manitoba, Winnipeg.

3 Present address: Dept. of Forestry and Wildlife, Virginia Polytechnic Institute, Blacksburg.






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Copyright © 1968 by the American Society of Animal Science.