HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Randel, R. D. Articles by Bellows, R. A. Search for Related Content PubMed PubMed Citation Articles by Randel, R. D. Articles by Bellows, R. A.

Effects of Various Mating Stimuli on the LH Surge and Ovulation Time following Synchronization of Estrus in the Bovine¹

U.S. Department of Agriculture and Montana Agricultural Experiment Station, Miles City 59301

Abstract

ESTRUS was synchronized in 39 cows by feeding 180 mg medroxyprogesterone acetate (MAP)/head/day for 11 days and injecting 5 mg estradiol benzoate on day 2 of MAP feeding. At the postsynchronization estrus, the cows were assigned to five groups differing in intensity of experimentally administered mating stimulation. Cows in Groups I, II, III and IV were maintained in a lot with estrogenized cows and observed constantly to detect first standing estrus. Group V cows were maintained with an epididymectomized bull and observed constantly for first standing estrus; they were allowed a single service by the bull. At detection of standing estrus, cows were removed from the lots and were given the appropriate mating stimuli. Cows in Group I received no further stimulus, cows in. Group II received artificial insemination with no clitoral stimulation, cows in Group III received artificial insemination with 10 sec. of manual stimulation of the clitoris; cows in Group IV were immediately bred three times in succession by a bull and cows in Group V received no further stimulation. Blood samples were collected hourly for 24 hr. from the onset of estrus and at 2-hr. intervals thereafter until ovulation was detected by rectal palpation. Serum LH was determined using double antibody radio-immunoassay. The LH surge was 4.5 hr. earlier in relation to the beginning of estrus (P<.10) in Group II than in Group I and ovulation time was 4.3 hr. earlier in relation to the beginning of estrus (P<.005) in Groups III, IV and V (greater stimulation) compared to Groups I and II (lesser stimulation). In this study, cervical stimulation tended to hasten the LH surge and clitoral stimulation hastened ovulation.

¹ This study was a contribution to Western Regional Research Project W-112, Reproductive Performance in Beef Cattle. Publication has been approved by the Director of the Montana Agricultural Experiment Station, Journal Series No. 384.

² U.S. Range Livestock Experiment Station, A.R.S., Miles City, Montana.

³ Montana Agricultural Experiment Station, Miles City, Montana.

⁴ We are indebted to Dr. L. E. Reichert, Jr., Emory University, Atlanta, Georgia, for providing purified bovine LH and to Dr. G. D. Niswender, Colorado State University, Fort Collins, Colorado, for providing anti-bovine LH anti-sera.