Animal Science, Department of


Document Type


Date of this Version

January 1979


Published in J Dairy Sci 1979, 62:760-767. Copyright © 1979 The American Dairy Science Association. Used by permission.


Large fluctuations in an artificial insemination sire's evaluations concern both dairymen and artificial insemination studs. Characteristics of three bulls with high initial values which dropped on later evaluations were compared with those of 17 "normal" bulls. Characteristics included genetic yield, management, genetic trend, environmental trend, and size of herds where daughters freshened, genetic merit of mates, and average age at freshening of daughters in first lactation. Evidence suggests that fluctuations are from preferential treatment of daughters of some sires as well as randomness inherent in methods of sampling and evaluating sires.