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Repeatability of Type Ratings in Dairy Cattle*

Iowa State College, Ames, Iowa

ABSTRACT

The usefulness of type for predicting production in dairy cattle has been investigated often. Although the correlations found between type and production have usually been small, type has persisted as a criterion in the selection of breeding animals. It appears that differences in type will continue to affect the price which buyers will pay for animals, or at least the ease with which different animals can be sold. Hence it is desirable to know something about the permanence, accuracy and other characteristics of estimates or ratings of type. The present study was undertaken to ascertain the amount and kind of variation occurring in type ratings when such ratings were made by different judges at intervals throughout an animal's life. The specific questions investigated were (1) the comparative accuracy of ratings made at different ages, (2) the repeatability of ratings separated by varying intervals of time, (3) the degree of agreement between judges in ratings given the same cow, (4) the specific causes of large changes in ratings, and (5) the extent to which future ratings can be predicted from one or more past ratings.

^* Journal paper No. J-929 of the Iowa Agricultural Experiment Station, Ames, Iowa. Project No. 31.