where yC is a vector of observations for crossbreds (mule
ducks); bC is a vector of fixed effects corresponding to
the combination of year, batch, and crammer effects
(12 levels); uAC (uBC) is the additive genetic effects of
the common dams (Muscovy sires) of mule ducks, as
expressed in the phenotypes of the mule ducks (population
C); eC is a vector of residual effects; X and Z
are incidence matrices relating records corresponding
effects. We stress that eC contains the remaining genetic
effects of crossbred animals