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 Thompson, D. L. Articles by Nett, T. M. Search for Related Content PubMed PubMed Citation Articles by Thompson, D. L., Jr. Articles by Nett, T. M.

Sexual Behavior, Seminal pH and Accessory Sex Gland Weights in Geldings Administered Testosterone and(or) Estradiol-17β¹

Colorado State University, Fort Collins 80523

Abstract

Sixteen stallions were castrated and 30 days later assigned to one of four treatments: (1) testosterone propionate (175 µg/kg body weight), (2) 17β-estradiol-3-benzoate (44 µg/kg body weight), (3) a combination of both steroids or, (4) vehicle only. These dosages were administered every other day for 18 days. The dosages were then doubled and continued for 20 days. Concentrations of testosterone and estradiol in serum decreased rapidly after castration and stabilized within about 6 hours. Mean concentrations of testosterone and estradiol maintained by the steroids were 1.4 and 90 pg/ml, respectively, during treatment at the lower dosage, and 2.6 and 186 pg/ml during treatment at the higher dosage. Libido and the ability to ejaculate were gradually lost after castration. Testosterone restored both aspects of sexual behavior within 2 weeks. Estradiol effectively restored libido at the higher dosage, but was less effective in restoring the ability to ejaculate. The pH of gel-free semen increased after castration and was subsequently decreased by treatment with testosterone or the combination of both steroids. Estradiol had no effect on seminal pH. Weights of the seminal vesicles, ampullae and prostate were greater in geldings treated with testosterone or with both steroids than in estradiol-treated or control geldings. Since estradiol alone was able to restore libido in geldings, it is possible that the maintenance of libido in intact stallions involves either estradiol secreted directly by the testes or estradiol arising from aromatization in peripheral tissues. Treatment with estradiol at either concentration, did not appear to affect the size or function of sex glands in geldings.

¹ Anim. Reprod. Lab. From a thesis submitted to the Graduate Faculty of Colorado State Univ. by the senior author in partial fulfillment of requirements for the degree of Doctor of Philosophy.

² Present address: Dept. of Anim. Sci., Louisiana State Univ., Baton Rouge 70803.