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Within-animal variances for flow rates of metabolites in an open-compartment model with continuous isotope infusion in sheep

Published online by Cambridge University Press:  27 March 2009

Helen K. Smith ,
J. A. Milne  and
R. W. Mayes
Helen K. Smith
Affiliation:
AFRC Unit of Statistics, The King's Buildings, Mayfield Road, Edinburgh
J. A. Milne
Affiliation:
Hill Farming Research Organisation, Bush Estate, Penicuik, Midlothian
R. W. Mayes
Affiliation:
Hill Farming Research Organisation, Bush Estate, Penicuik, Midlothian
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Summary

Flow rates of metabolites in an open-compartment model can be calculated from specific activity measurements taken at equilibrium during continuous infusion of an isotope. The within-animal variance gives an estimate of the precision of the flow rate.

The Jack-knife method of calculating within-animal variances is described. It was evaluated using simulated data, and shown to be superior to a simpler method, the Single Section method.

The increase in experimental accuracy caused by increasing the number of specific activity samples per animal depends on the ratio of between- to within-animal variance components (B/W). For three experiments with sheep, 23 of the 30 values B/W for the different flow rates ranged from 0·25 to 1·5. For this range between six and 12 samples per animal are needed.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 107 , Issue 3 , December 1986 , pp. 529 - 535
Copyright
Copyright © Cambridge University Press 1986

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References

REFERENCES

Bissell, A. F. & Ferguson, R. A. (1975). The jackknife – toy tool or two-edged weapon? The Statistician 24, 79–100.CrossRefGoogle Scholar
Macrae, J. C., Milne, J. A., Wilson, S. & Spence, A. M. (1979). Nitrogen digestion in sheep given poorquality indigenous hill herbage. British Journal of Nutrition 42, 525–534.CrossRefGoogle Scholar
Mann, J. & Gurpide, E. (1966). Generalised rates of transfer in open systems of pools in the steady state. Journal of Clinical Endocrinology and Metabolism 26, 1346–1354.CrossRefGoogle ScholarPubMed
Mayes, R. W. & Lamb, C. S. (1982). The effect of supplementary starch and urea on the digestion of a heather-based diet by sheep. In Forage Protein in Ruminant Animal Production. British Society of Animal Production Occasional Publication No. 6 pp. 149–150 (ed. Thompson, D. J., Beever, D. E. & Gunn, R. G.) Edinburgh.Google Scholar
Mead, R. & Curow, R. N. (1983). Statistical Methods in Agriculture and Experimental Biology, 1st edn.London: Chapman and Hall.CrossRefGoogle Scholar
Milne, J. A. & Mayes, R. W. (1984). The use of simple compartmental models in sheep metabolism studies. Proceedings of the Nutrition Society 43, 197–204.Google Scholar
Nolan, J. V., Norton, B. W. & Leng, R. A. (1976). Further studies of the dynamics of nitrogen metabolism in sheep. British Journal of Nutrition 35, 127–146.CrossRefGoogle ScholarPubMed
Wilson, S., Macrae, J. C. & Buttery, P. J. (1983). Glucose production and utilisation in non-pregnant, pregnant and lactating ewes. British Journal of Nutrition 50, 303–316.CrossRefGoogle ScholarPubMed