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Protein synthesis and degradation in the mammary gland of lactating goats

Published online by Cambridge University Press:  01 June 2009

V. Hutton Oddy ,
Derek B. Lindsay  and
Ivan R. Fleet
V. Hutton Oddy
Affiliation:
AFRO Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT, UK
Derek B. Lindsay
Affiliation:
AFRO Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT, UK
Ivan R. Fleet
Affiliation:
AFRO Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT, UK
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Summary

Lactating goats were given a close arterial infusion of [1-14C]leucine and [4,5-3H]4-methyl-2-oxopentanoic acid into one half of the mammary gland at 2–3 weeks and 34–39 weeks after kidding. Rates of protein synthesis, degradation and net output were determined from measurements of arteriovenous difference and blood flow using a model of leucine metabolism previously developed for muscle (Oddy & Lindsay, 1986). Protein leucine output in milk (Y μmol/min) correlated well with the difference between synthesis and degradation (X μmol/min) derived from the model:

There was substantial synthesis and degradation of protein within the mammary gland. Although only an approximate value could be obtained for the partitioning of protein synthesis and degradation between tissue and milk proteins, there was evidence of appreciable turnover of both. There was no significant difference between mammary leucine and protein metabolism in early and late lactation other than that imparted by a greater mass of mammary tissue in early lactation, although there was a tendency for greater oxidation of leucine in late lactation.

Type
Original articles
Information
Journal of Dairy Research , Volume 55 , Issue 2 , May 1988 , pp. 143 - 154
Copyright
Copyright © Proprietors of Journal of Dairy Research 1988

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References

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