Relationships Between First Lactation, Later Performance, and Length of Herd Life in Holstein-Friesian Cattle

Abstract

This study included 16,583 mature equivalent DHIA records of 4,819 daughters of 29 A.I. Holstein sires from 1,528 herds. First records were stratified into 11 milk and 9 milk fat groups at 1,000- and 50-lb intervals, respectively, to ascertain the correlation of first-lactation production with subsequent performance and length of herd life. Heifers in higher groups produced significantly (P < .01). Paternal half-sib heritability estimates for lactations completed and age at last calving were 0.13 and 0.14, respectively. Neither value was statistically significant. © 1965, American Dairy Science Association. All rights reserved.