Probable infectious stunting syndrome in replacement pullets

Infectious stunting is recorded in detail in three egg-type pullet flocks and one egg-type breeder flock. Three different strains of brown egg birds were involved. The clinical effects were less severe than those usually seen in broilers. Excessive mortality during the first three weeks was a feature of all four flocks. Fibrous atrophy of the pancreas was seen in one flock and could still be found in individual birds at 18 weeks old. Bone disorders were seen in two flocks. Severe anaemia was seen in some birds in one flock. Severe emaciation of the pectoral muscles was an unexplained and prominent feature of all the flocks. As the birds grew the visible and clinical evidence of stunting was much reduced and it appeared that compensatory growth took place so that by 18 weeks old the flocks appeared normal and the culling rate at caging was negligible.