Effects of Exogenous Growth Hormone on Mammary Function in Lactating Goats

T. B. Mepham; S. E. Lawrence; A. R. Peters; I. C. Hart

doi:10.1055/s-2007-1014757

Hormone and Metabolic Research, Table of Contents

Horm Metab Res 1984; 16(5): 248-253
DOI: 10.1055/s-2007-1014757

Effects of Exogenous Growth Hormone on Mammary Function in Lactating Goats

T. B. Mepham¹ , S. E. Lawrence¹ , A. R. Peters¹ , I. C. Hart²

¹Department of Physiology and Environmental Science, University of Nottingham Faculty of Agricultural Science, Sutton Bonington, Loughborough, Leics, United Kingdom
²Department of Physiology, National Institute for Research in Dairying, Shinfield, Reading, Berks, United Kingdom

Abstract

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Summary

The galactopoietic effect of daily injections, for five day periods, of growth hormone was examined by measuring milk yield, mammary blood flow and arteriovenous differences of glucose and amino acids on 12 occasions in four goats.

In 10 periods there were marked increases (mean 18.1%) in mammary blood flow (8 statistically significant) and less-marked increases (mean 8.0%) in milk yield (6 statistically significant). On 8 of the occasions on which it was measured the maximum blood plasma growth hormone concentration was increased to more than 8 ng/ml.

There were no statistically significant changes in mammary arteriovenous concentration differences of glucose or amino acids in response to growth hormone injections.

It is suggested that, contrary to the usual situation in which the rate of mammary blood flow appears to be regulated by the metabolic activity of the gland, the galactopoietic response to growth hormone may be a consequence of elevated blood flow, which increases the supply to the gland of rate-limiting metabolic substrates.

Key-Words:

Lactation - Growth Hormone - Mammary Gland

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