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Changes in type Classification Ratings of Immature Holstein Females. II. The Subratings¹

New Jersey Agricultural Experiment Station, Sussex

ABSTRACT

Subratings of Holstein females of the New Jersey Agricultural Experiment Station from 6 mo. of age to the end of the first lactation, made by official inspectors semiannually from 1945 to 1956, were analyzed. Ratings of 94 animals were grouped according to age, 6 to 18 mo. (yearlings), 18 mo. to freshening (2-yr-olds), first lactation (first-calf heifers), and 6 mo. to freshening (nonadults), with each animal being represented by two or more ratings in each period. Means of ratings of first-calf heifers were usually lower than ratings prior to freshening, although a systematic age influence often was not present. Differences in sire-group means were seldom significant; age-sire interactions were significant in some comparisons for some characteristics and in other comparisons for others. Ratings prior to 18 mo. are of little value in predicting ratings of first-calf heifers. Repeatability of average ratings between 2-yr.-olds and first-calf heifers ranged from 0.08 (dairy character) to 0.63 (rump). While more success may be obtained by using these later ratings, the relationships are still too low to justify selection for type in any but the most extreme cases.

¹ Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers University, the State University of New Jersey, Department of Dairy Industry, New Brunswick. This study was part of a joint project between the Holstein-Friesian Association of America and the New Jersey Agricultural Experiment Station.