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Evaluation of Protein Feeds for Dairy Cows

Published online by Cambridge University Press:  22 November 2017

A.J.F. Webster ,
M.A. Kitcherside ,
J.R. Keirby  and
P.A. Hall
A.J.F. Webster
Affiliation:
University of Bristol, Langford House, Langford, Bristol BS18 7DU
M.A. Kitcherside
Affiliation:
University of Bristol, Langford House, Langford, Bristol BS18 7DU
J.R. Keirby
Affiliation:
University of Bristol, Langford House, Langford, Bristol BS18 7DU
P.A. Hall
Affiliation:
University of Bristol, Langford House, Langford, Bristol BS18 7DU
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Extract

A method is described for the description of feeds and feed mixtures in terms of their ability to provide truly digestible amino nitrogen (N) for cattle. Total basal endogenous N (TEN) loss is assumed to be 0.35g N/kg bodyweight0.75 (Report of A.R.C, Protein Working Group).

Feedstuffs are analysed for total N (TN), non-protein N and detergent-insoluble N (neutral detergent, NDIN and acid detergent, ADIN, van Soest, 1982). The disappearance of N is measured from samples incubated in nylon bags in the rumen of dairy cows for 0, 4, 8, 18, 24 and (for forages) 48 hr. Residual N in nylon bags after 18 hr incubation is subjected to 48 hr pepsin digestion to give pepsin-insoluble undegraded dietary N (PSUDN). Digestibility trials are run using three sheep for each test feed and faecal N analysed according to a modification of the method of Mason (1969) into detergent-insoluble faecal N, soluble faecal N and bacterial and endogenous debris N. Urinary N has also been measured since 1983.

Type
Protein Allowances for Ruminants
Information
Proceedings of the British Society of Animal Production (1972) , Volume 1984 , March 1984 , pp. 105
Copyright
Copyright © The British Society of Animal Production 1984

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References

Mason, V.C. (1969) J. agric. Sci. 73, 99.Google Scholar
Ørskov, E.R. & McDonald, I. (1979) J. agric. Sci. 92, 499.Google Scholar
van Soest, P. (1982) “The nutritional ecology of the ruminant.” Cornwallis Books, Oregon.Google Scholar