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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by THIBIER, M. Search for Related Content PubMed Articles by THIBIER, M.

PERIPHERAL PLASMA TESTOSTERONE CONCENTRATIONS IN BULLS AROUND PUBERTY

Union Nationale des Coopératives d'Elevage et d'Insémination Artificielle, and Institut National Agronomique de Paris-Grignon, 78850 Thiverval-Grignon, France

(Received 11th July 1974)

It is now well established that dairy bulls attain their mature rate of spermatogenesis by 1 year of age (Attal & Courot, 1963; Macmillan & Hafs, 1968) and that gonadotrophins and steroid hormones are involved in the process of initiation and maintenance of spermatogenesis (Steinberger & Steinberger, 1969). Already by this age, testosterone is the most important androgen secreted by the interstitial tissue (Lindner, 1969). Rawlings, Hafs & Swanson (1972) observed an increase in the plasma levels of testosterone in five bulls up to 11 months of age and then a drop the following month. Since the levels found were highly variable, it was apparent that data from quite a large number of animals would be required to establish whether there is a significant increase or decrease in the