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 Britt, J. H. Articles by Stevenson, J. S. Search for Related Content PubMed PubMed Citation Articles by Britt, J. H. Articles by Stevenson, J. S.

Estrus in Relation to Time of Administration of Prostaglandin F² to Heifers¹

Department of Dairy Science, Michigan State University, East Lansing 48824

ABSTRACT

Holstein heifers (95) were given two injections of prostaglandin F², the first on day 0 and the second either at 0600 h or 1800 h on day 12. Interval from the second treatment to first observation of estrus did not differ between heifers treated during the morning (69.8 ± 4.4 h) or evening (72.7 ± 5.2 h). However, estrus was detected sooner after treatment of heifers during July 1975 (49 ± 2 h) than after treatment during June 1976 (85 ± 8 h). Estrus began at 64 ± 5, 73 ± 7, and 76 ± 7 h after the second injection during August 1975, October 1976, and December 1975. Heifers treated during the morning in October were detected in estrus sooner (57±3 versus 95 ± 13 h) than those treated during the evening. An interaction of season by time may affect interval from prostaglandin F² treatment to onset of estrus.

¹ Michigan Agricultural Experiment Station Journal Article No. 8320.

² Department of Animal Science, North Carolina State University, Raleigh 27607.