The goalofanyanimalbreederistoevaluatesirein
younger agetoreducethecostofrearing.Dairycattle
evaluation usingtest-daymilkyields(TDMY)hassignifi-
cant advantagesoverthe305-daymilkyield(Mostert
et al.,2006). TheuseofTDMYallowsamoreaccurate
understanding ofcontemporarygroupsandassociated
environmental effects.Further,characteristicsassociated
with TDMYincludetheuseofadditionalinformationona