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 Gonzalez-Padilla, E. Articles by Wiltbank, J. N. Search for Related Content PubMed PubMed Citation Articles by Gonzalez-Padilla, E. Articles by Wiltbank, J. N.

Puberty in Beef Heifers. III. Induction of Fertile Estrus^{1, 2,}

Colorado State University,^,5 Fort Collins 80521

Abstract

By utilizing estrogen and progesterone, it appeared possible to mimic the changes occurring in blood hormone levels near puberty. This suggested the possibility of induction of puberty in beef heifers. Four trials were conducted to test this hypothesis and a fifth to explore the effect of treatment with steroids in induction of estrus in suckling anestrous cows.

Trial 1. At the Eastern Colorado Range Station, 45 Hereford, Angus-Hereford and Charolais-Hereford heifers were divided within breed into a control group (C), Group I which received on day 1 a single IM injection of 5 mg of estradiol valerate (EV) plus 3 mg of 17-acetoxy 11 beta-methyl 19 nor-preg-4ene 3, 20 dione (norgestomet), and a 6 mg ear implant of norgestomet which was removed 9 days later, and group P which received 5 mg of estradiol valerate, IM on day 6, daily IM injections of 20 mg of progesterone from day 6 to day 10 and 2 mg of estradiol-17ß on day 12. By 4 days after implant removal, estrus was detected in 0,94 and 93% for groups C, I and P, respectively.

¹ Published with the approval of the Director of the Colorado State University Experiment Station as Scientific Series Paper No. 1964.

² All hormones and partial support for these experiments were kindly provided to us by G. D. Searle, Co. of Chicago, Illinois.

³ Present Address: INIP, Km 15 1/2 de la Carr., Mexico Toluca, Palo Alto, Mexico 10 D. F.

⁴ Present Address: Texas A & M University, Agricultural Research Station, St. Rt. 2 Box 43C, Beeville, Texas 78102.

⁵ Department of Physiology and Biophysics and Department of Animal Sciences. detected in 0, 94 and 93% for groups C, I and P, respectively.