LESSONS FROM 30 GENERATIONS BREEDING FOR DISEASE RESISTANCE IN EGG-TYPE CHICKENS

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.