Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-24T14:08:17.306Z Has data issue: false hasContentIssue false
  • English
  • Français

Prediction of the voluntary intake of grass silages by beef cattle 3. Precision of alternative prediction models

Published online by Cambridge University Press:  02 September 2010

A. J. Rook ,
M. S. Dhanoa  and
M. Gill
A. J. Rook
Affiliation:
AFRC Institute for Grassland and Animal Production, Hurley, Maidenhead SL6 5LR
M. S. Dhanoa
Affiliation:
AFRC Institute for Grassland and Animal Production, Hurley, Maidenhead SL6 5LR
M. Gill
Affiliation:
AFRC Institute for Grassland and Animal Production, Hurley, Maidenhead SL6 5LR
Get access

Abstract

The precision of a number of new models for predicting silage intake by beef cattle was investigated with independent data using the mean-square prediction error and compared with two previously published models (Agricultural Research Council, 1980; Lewis, 1981). The new models generally performed well relative to the previous models.

The new models included a number constructed using the technique of ridge regression which were shown to be consistently better predictors than the models obtained from the same estimation data by stepwise least-squares regression. Better prediction was also obtained by reducing the number of variables in the least-squares models below that required to maximize R2 in the estimation data. The poor performance of the least-squares models with the best R2 may be attributed to collinearity between the independent variates in the estimation data.

Most of the models considered overpredicted relative to observed intakes. This may have been the result of differences in breed type and management of the animals between the test data and the estimation data used to construct the models, that is the use of the models with the test data involved a degree of extrapolation.

It is concluded that ridge regression and deletion of variables offer a positive step forward in intake prediction compared with models based on maximizing R2 in the estimation data. However, further work is needed to clarify the effect of factors such as breed and rearing system on intake and to clarify the usefulness of various fibre measures in intake prediction. A number of new models are proposed which utilize a range of input variables thus allowing flexibility in their use in practical situations.

Keywords

beef cattleintakemathematical modelssilage
Type
Research Article
Information
Animal Production , Volume 50 , Issue 3 , June 1990 , pp. 455 - 466
Copyright
Copyright © British Society of Animal Science 1990

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Agricultural Research Council. 1980. The Nutrient Requirements of Ruminant Livestock. Commonwealth Agricultural Bureaux, Slough.Google Scholar
Barber, W. P., Adamson, A. H. and Altman, J. F. B. 1984. New methods of forage evaluation. In Recent Advances in Animal Nutrition — 1984 (ed. Haresign, W. and Cole, D. J. A.), pp. 161–176. Butterworths, London.CrossRefGoogle Scholar
Bibby, J. and Toutenburg, H. 1977. Prediction and Improved Estimation in Linear Models. Chapter 1.5.4. Wiley, London.Google Scholar
Demarquilly, C. 1973. Chemical composition, fermentation characteristics, digestibility and voluntary intake of forage silages: changes compared to initial green forage. Annales de Zootechnie 22: 199–218.Google Scholar
Dewar, W. A. and McDonald, P. 1961. Determination of dry matter in silage by distillation with toluene. Journal of the Science of Food and Agriculture 12: 790–795.CrossRefGoogle Scholar
Haigh, P. M. and Hopkins, J. R. 1977. Relationship betwen oven and toluene dry matter in grass silage. Journal of the Science of Food and Agriculture 28: 477–480.CrossRefGoogle Scholar
Hoerl, A. E. and Kennard, R. W. 1970. Ridge regression: biased estimation for nonorthogonal problems. Technometrics 12: 55–67.CrossRefGoogle Scholar
Leaver, J. D. and Yarrow, N. H. 1980. A note on the effect of social rank on the feeding behaviour of young cattle on self-feed maize silage. Animal Production 30: 303–306.Google Scholar
Le Du, Y. L. P., Baker, R. D. and Barker, J. M. 1976. Milk-fed calves. 2. The effect of length of milk feeding period and milk intake upon herbage intake and performance of grazing calves. Journal of Agricultural Science, Cambridge 87: 197–204.CrossRefGoogle Scholar
Lewis, M. 1981. Equations for predicting silage intake by beef and dairy cattle. Proceedings of the Sixth Silage Conference, Edinburgh, pp. 35–36.Google Scholar
Mertens, D. R. 1985. Effect of fiber on feed quality for dairy cows. Proceedings of the 46th Minnesota Nutrition Conference, pp. 209–224.Google Scholar
Ministry of Agriculture Fisheries and Food. 1986. Feed Composition: UK Tables of Feed Composition and Nutritive Value for Ruminants. Chalcombe Publications, Marlow.Google Scholar
National Research Council. 1987. Predicting Feed Intake of Food-producing Animals. National Academy Press, Washington, DC.Google Scholar
Neal, H. D. St C., Gill, M., France, J., Spedding, A. and Marsden, S. 1988. An evaluation of prediction equations incorporated in a computer program to ration beef cattle. Animal Production 46: 169–179.Google Scholar
Petchey, A. M. and Broadbent, P. J. 1980. The performance of fattening cattle offered barley and grass silage in various proportions either as discrete feeds or as a complete diet. Animal Production 31: 251–257.Google Scholar
Phipps, R. H., Bines, J. A. and Cooper, A. 1983. A preliminary study to compare individual feeding through Calan electronic feeding gates to group feeding. Animal Production 36: 544 (Abstr.).Google Scholar
Rook, A. J., Dhanoa, M. S. and Gill, M. 1990. Prediction of the voluntary intake of grass silages by beef cattle. 2. Principal component and ridge regression ANALYSES. Animal Production 50: 439–454.Google Scholar
Rook, A. J. and Gill, M. 1990. Prediction of the voluntary intake of grass silages by beef cattle. 1. Linear regression analyses. Animal Production 50: 425–438.Google Scholar
Taylor, St C. S., Moore, A. J. and Thiessen, R. B. 1986. Voluntary food intake in relation to body weight among British breeds of cattle. Animal Production 42: 11–18.Google Scholar
Thiel, H. 1966. Applied Economic Forecasting. Chapter 2. North Holland Publishing Company, Amsterdam.Google Scholar
Thomas, C. 1987. Factors affecting substitution rates in dairy cows on silage based rations. In Recent Advances in Animal Nutrition — 1987 (ed. Haresign, W. and Cole, D. J. A.), pp. 205–218. Butterworths, London.CrossRefGoogle Scholar