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Permanence of Type Ratings in Young Holstein Heifers^1,2,

Department of Dairy Science, The Ohio State University, Columbus

ABSTRACT

To determine the repeatability of type ratings in young heifers, 544 animals in five herds were evaluated at 3, 6, and 12 mo. of age. Evaluations were made on a ten-division score-card basis, and each animal was scored independently by two evaluators working simultaneously. Repeatabilities of the various type components were estimated by intra-heifer, intra-herd correlations. The correlation values between 3- and 6-mo. scores ranged from 0.2 to 0.3 for the different score-card divisions. Values between 6 and 12 mo. showed a somewhat wider range, and those between 3 and 12 mo. were somewhat lower. Variations among herds and among score-card divisions within herds are a definite limitation upon the usefulness of this information in small groups of heifers. Definite, characteristic age changes were observed in all score-card divisions. The most consistent of these were a progressive improvement in shoulders and chest (more marked between 3 and 6 mo., but also significant between 6 and 12 mo.), a drop in scores for rump and thigh between 6 and 12 mo., and a marked improvement in feet and legs between 3 and 6 mo. With some exceptions, there was a rather strong tendency for heifers to be scored higher at 6 mo. of age than at other ages. This was particularly noticeable in total score.

¹ This study was made through the cooperation of the Dairy Husbandry Research Branch, in the cooperative project, "Improvement in Dairy Cattle Through Breeding."

² These data were taken from material submitted by the senior author in partial fulfillment of the requirements for the Doctor of Philosophy degree, The Ohio State University, Columbus, Ohio.

³ Agent of the Dairy Husbandry Research Branch, USDA. Present address: University of Minnesota, St. Paul, Minnesota.