(Simm 1998). Although this means that the process
of selection can be speeded up and targeted, it carries the
disadvantage that in order to measure heritabilities and
correlations, poultry are often selected in controlled environments
that are different from the ones the offspring will
encounter. For example, the parent and grandparent broiler
breeders have until recently been selected in disease-free
environments different from the commercial farms (de Jong
& Guémené 2011)