Egg-type chickens have been bred for hen-housed production since many
decades,which includes appropriate attention to survival and health. N
egative correlations between health and egg production are unlikely. B
reeding for resistance concentrates on those disease agents or stresso
rs which cannot be controlled by hygiene, vaccination, nutrition and g
ood husbandry. Pedigreed crossline sisters of the pure-line pedigree p
opulations are evaluated in sub-optimal environments in different loca
tions. An important Feature of modern egg-type breeding is the utiliza
tion of specific combining ability in multiple strain crosses. The cur
rent organisational structures do not support the search for superior
combining ability in cattle breeding, but this could be the most impor
tant lesson from poultry breeding.