Induction of vitamin A deficiency in turkeys.

The objective of this study was to determine the relationship between the hepatic vitamin A (VitA) level and the pathologic changes in the oropharynx and esophagus of VitA-deficient turkeys. Study turkeys were provided with a diet sufficient (11,000 IU/kg) or deficient (2750 IU/kg) in VitA from 4 to 17 wk of age. Body weight, bacterial culture, and tissues from internal organs were collected at weekly intervals. VitA deficiency causes epithelial tissue damage in poultry. This epithelial damage was seen grossly as white plaques in the oropharynx and esophagus and histologically as squamous metaplasia of mucosal glands and keratinization of epithelium. No significant difference in body weights was seen among the groups. Moreover, no pathogenic bacteria was isolated during sampling periods. Liver VitA levels declined significantly after consumption of low VitA diet for 3 wk and were depleted after 5 wk. Squamous metaplasia due to VitA deficiency developed in the esophagus after 3 wk and in the oropharynx after 4 wk of consuming a VitA-deficient diet.