FLUCTUATIONS IN SIRE EVALUATIONS

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. © 1979, American Dairy Science Association. All rights reserved.