The significance of age of the chick in establishing the ICP index.
D000367:Age Factors; D000818:Animals; D002642:Chick Embryo / Q000276:immunology*; D002645:Chickens / Q000276:immunology*; D005321:Extraembryonic Membranes / Q000276:immunology; D009521:Newcastle Disease / Q000276:immunology / Q000662:veterinary*; D009522:Newcastle disease virus / Q000472:pathogenicity*; D011201:Poultry Diseases / Q000276:immunology*