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 Ohlson, D. L. Articles by Jenkins, T. G. Search for Related Content PubMed PubMed Citation Articles by Ohlson, D. L. Articles by Jenkins, T. G.

Plasma Growth Hormone, Prolactin and Thyrotropin Secretory Patterns in Hereford and Simmental Calves¹

University of Idaho, Moscow 83843 and and US Department of Agriculture Roman L. Hruska US Meat Animal Research Center⁵, Clay Center, NE 68933

Abstract

An experiment was conducted to test the hypothesis that bull calves of a larger, faster growing breed of cattle exhibit greater secretory activity of anabolic pituitary hormones than bull calves of a smaller, slower growing breed. Calves of both breeds were raised under similar conditions and maintained on the same diet for approximately 4 weeks before the blood sampling period. Simmental bull calves had higher (P<.01) average daily gains and a heavier (P<.01) mean body weight than Hereford bull calves. Overall plasma growth hormone (GH) concentrations were higher (P<.01) in Simmental bull calves than in Hereford bull calves. Mean baseline GH was also higher (P<.05) in Simmentals. Overall and baseline concentrations of prolactin (PRL) were similar for both breeds. Mean amplitude of PRL secretory spikes was higher (P<.05) for Simmental than for Hereford bull calves. There was no breed effect on any variable of thyrotropin secretion. These data suggest that representatives of a larger, faster growing breed of cattle (Simmental) exhibit greater secretory activity of GH and PRL than do representatives of a smaller, slower growing breed (Hereford).

¹ Idaho Agr. Exp. Sta. Pub. No. 80410.

² Dept. of Anim. Sci.

³ These studies were supported in part by the USDA and the Idaho Agr. Exp. Sta.

⁴ The authors express their gratitude to Ms. Debbi Blann for her excellent technical assistance, Dr. A. E. Wilhelmi for supplying purified GH for radioiodination and reference standard, Dr. J. G. Pierce for supplying purified TSH; Dr. L. E. Reichert for supplying purified PRL, and the NIH, National Pituitary Agency, for supplying bovine PRL and TSH used as reference standards.

⁵ USDA-SEA-AR.