First Classification Score and Length of Herd Life

The relationship of first score and length of life in the herd was measured in Holstein females two or three years of age at first classification. The regression of herd life (number of times classified) on the first over-all type score (nearly all values were between 65 and 90 points) was 1.7 months. Correlation between first classification score and herd life was approximately 0.2, indicating that less than 5% of the variation in herd life could be attributed to the relationship between first score and herd life. Differences among herds accounted for about 10% of the total variance in overall type score and in the individual type traits. Differences among sires accounted for from 5 to 8% of the variation in over-all score and in each of the categories (general appearance, dairy character, body capacity, mammary system, fore udder, rear udder, legs and feet, and rump) of the Holstein classification system. Similarly, differences among classifiers accounted for 2 to 6% of the total variance. Classifier variation was greatest in the areas of general appearance, body capacity, and legs and feet. An analysis of variance components on 7,927 artificially inseminated (AI) sired animals scored from 1958 through 1963 gave a heritability of 0.16 for over-all type score. Heritabilities of over-all score from each of the six years varied widely. I t is a common belief in the dairy industry that the length of a dairy cow's productive life is strongly influenced by her physical characteristics. I t is one of the major reasons dairy breed associations have conducted type classification programs for nmre than 30 years. Classification scores from animals in herds that frequently participated in the Holstein-Friesian classification program in New York were used Received for publication April 20, 1967. to study the relationship between first type score and length of herd life. An assessment of the amount of variation among scores for type in a large population of cattle was sought. Thexe are limitations of the data, in that an upper limit is placed upon the score of a first calf heifer and that only a small proportion of all dairy herds classify. Itowever, herds that do classify are the major source of sires for artificial breeding units and for individual breeding herds. The problem of evaluating sires for their ability to transmit desirable type traits continues to be difficult. Therefore, it seems important to determine from field data what influence the herd, the sire, and the classifier might have upon the variation found in the type scores of dairy animals. The components o£ variation due to sires can be used to estimate what progress can be made in selecting for improved type.