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Comparison of systems for estimating protein allowances for dairy cows

Published online by Cambridge University Press:  21 November 2017

C.J. Waters ,
R.J. Dewhurst  and
A.J.F. Webster
C.J. Waters
Affiliation:
Department of Animal Husbandry University of Bristol Langford House, Langford, Bristol BS18 7DU
R.J. Dewhurst
Affiliation:
Department of Animal Husbandry University of Bristol Langford House, Langford, Bristol BS18 7DU
A.J.F. Webster
Affiliation:
Department of Animal Husbandry University of Bristol Langford House, Langford, Bristol BS18 7DU
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Extract

The proposed Agricultural Research Council (ARC 1984) protein evaluation system for ruminants provides lower nitrogen allowances than any other. (National Research Council 1985; Alderman 1987). A U.K. Interdepartmental Working Party (IDWP) was set up to consider the ARC (1980) proposals and recommend a practical protein evaluation system for ruminants for use by the advisory services. Its provisional proposals have been reported by Webster (1987). This trial was set up to provide a practical evaluation of the two systems in a commercial dairy herd.

Animals. Thirty-three Friesian cows (mean livewewight 590kg, mean previous milk yield 6120 kg), in early lactation were blocked according to (a) previous treatment, (b) number of previous lactations and (c) previous milk yield. The cows were randomly allocated within blocks to one of three dietary treatments.

Treatments. Dietary nitrogen allowances were calculated, according to (1) ARC(1984) and (2) IDWP (Webster, 1987) except that the ARC (1984) concept of essential amino acid nitrogen was included in the IDWP calculations. The difference in nitrogen allowances between the two systems was so great as to warrant a third intermediate treatment (INT), calculated to provide allowances mid-way between the other two.

Type
Ruminant Nutrition and Production
Information
Proceedings of the British Society of Animal Production (1972) , Volume 1987 , March 1987 , pp. 56
Copyright
Copyright © The British Society of Animal Production 1987

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References

Alderman, G. (1987) Comparison of rations calculated in the different systems. Current Topics in Veterinary Medicine and Animal Science. Martinus Nijhoff (in press).Google Scholar
ARC (1980) The nutrient requirements of ruminant livestock. CAB, Slough.Google Scholar
ARC (1984) The nutrient requirements of ruminant livestock. Supplement No.l. CAB, Slough.Google Scholar
Carruthers, V.R. & Bryant, A.M. (1983) Evaluation of the use of chromic oxide to estimate the feed intake of dairy cows. New Zealand Journal of Agricultural Research. 26: 183–186.Google Scholar
NRC (1985) Ruminant nitrogen usage. National Academy Press, Washington, D.C.Google Scholar
Webster, A.J.F. (1987) Metabolizable protein - The U.K. approach. Current Topics in Veterinary Medicine and Animal Science. Martinus Nijhoff (in press).Google Scholar