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Journal of Dairy Science Vol. 71 No. 3 870-878
© 1988 by American Dairy Science Association ®
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A Field Study of Grouping Cows by Nutrient Requirements for Feeding

B. L. Schucker1, M. L. McGilliard, R. E. James and C. C. Stallings

Department of Dairy Science, College of Agricultural and Life Sciences, Virginia Agricultural Experiment Station, Virginia Polytechnic Institute and State University, Blacksburg 24061

ABSTRACT

A field study was designed to evaluate the practicality of a system of grouping cows based on nutrient requirments for concentrations of CP and TDN. This cluster system was computerized and implemented in 10 commercial dairy herds feeding total mixed rations. Grouping recommendations based on DHIA records were provided for 12 mo. The final modified computer program was applied in retrospect to the 12 mo of production records of the herds. The cluster procedure, when compared with a milk only grouping with all other constraints identical, placed in the high groups cows 7 mo younger and 16 kg lighter, requiring .9% more TDN and .6 kg less DM. The cluster system placed in the low groups cows 9 mo older and 22 kg heavier, requiring 1.2% less TDN concentration and .8 kg more DM. Intragroup correlations for the cluster and milk systems were .59 and .41 for TDN, .65 and .57 for CP, and .19 and .48 for intake of DM, indicating that cows in clustered groups were more homogeneous in nutrient requirements than cows grouped by milk. Analysis of predicted feed cost per cow per day indicated similar feed costs for each grouping system.

FOOTNOTES

1 Present Address: Harford County Extension, Bel Air, MD 21014. This study was funded by the Virginia Agricultural Foundation.






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Copyright © 1988 by the American Dairy Science Association ®.