To examine the usefulness of more frequent evaluation
in identifying new bulls of superior genetic merit, mean
and absolute differences in PTA between evaluations
were studied for the top 20 bulls for milk, fat, and protein
in May or August 1997 among bulls with initial evaluations
in the corresponding month. Mean and absolute
differences between PTA and parent average (PA), the
mean of parent PTA, also were examined, and correlations
of PA with initial and later evaluations were calculated.