The economic importance of egg drop syndrome 1976 [a new disease] in layer breeders in Singapore

agentes nocivos agricultura agriculture animal animal domestique animal production animales animals asia asie aves de corral aves domesticas birds chickens disease prevention diseases domestic animals domesticated birds egg production facteur nuisible galliformes immunisation immunization injurious factors laying performance oiseau oiseau domestique performance de ponte pollo poulet poultry production production animale production d'oeufs rendimiento en la postura singapore singapour singapur vertebrados vertebrates vertebre volaille