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Journal of Dairy Science Vol. 30 No. 5 273-278
© 1947 by American Dairy Science Association ®
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Within-Cow Regression of Milk-Energy Yield on Age and Liveweight1

W. L. Gaines

Illinois Agricultural Experiment Station, Urbana

H. P. Davis and R. F. Morgan

Nebraska Agricultural Experiment Station, Lincoln

ABSTRACT

INTRODUCTION

Certain DHIA records of cows in Illinois farm herds (3, 4) showed that milk-energy yield is practically unaffected by age of cow, independent of liveweight. On the other hand, milk-energy yield is greatly affected by live-weight, independent of age. These results relate to Holstein and Jersey cows, separately by breed. In each breed some of the cows were registered animals and some were not.

A similar result was found (1) from certain more accurate records (e.g., milk weighed at each milking instead of one day per month) in the Nebraska Station herd at Lincoln. The Nebraska data are for registered cows of the Ayrshire, Guernsey, Holstein, and Jersey breeds, all treated as one group. The lumping of the data for the four breeds quite possibly could disturb the general validity of the result, because the Holsteins were markedly larger than the other breeds and at the same time had a decidedly higher milk-energy yield per unit liveweight than the other breeds.

FOOTNOTES

1 Published with approval of the Director as Paper no. 409, Journal Series, Nebraska Agricultural Experiment Station, and with approval of the Director of the Illinois Station. The original observations were made at the Nebraska Station, and the computations were made at the Illinois Station, utilizing IBM punched-card machines.






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Copyright © 1947 by the American Dairy Science Association ®.