SELECTION FOR DISEASE RESISTANCE IN POULTRY - GENERAL OR SPECIFIC

Causes of mortality in layers and broilers are discussed. In experimen tal flocks at Spelderholt all dead and diseased birds are autopsied. A mong this ''normal'' mortality non-infectious causes were about twice as frequent as infectious causes. In selected broiler lines, mortality was two to three times higher in weight selected birds than in chicke ns selected for feed conversion. These differences were caused by both mortality related to infectious diseases and mortality related to hea rt and circulation problems.