Excess dietary vitamin A in the growing chick: effect of fat source and vitamin D.

Studies were conducted to determine the nutritional interrelationship between different fat sources, vitamin D3 (vit D) and excess dietary vitamin A (vit A) in the growing chick. Birds tolerated as much as 30 times the recommended level of vit A without compromising performance or skeletal development as measured by bone ash. The response to excess dietary vit A was not influenced by the type of dietary lipid (corn oil, tallow, or poultry oil). No nutritional interaction between vit A (1,500, 15,000, or 45,000 IU/kg) and vit D (100 or 1000 ICU/kg) was detected as measured by growth, bone ash, growth hormone, incidence of tibial dyschondroplasia (TD), or rickets. Serum alkaline phosphatase activity, however, was significantly affected by vit A, vit D, and age of the chicks. The higher vit D level significantly enhanced growth, bone ash, and reduced incidence of rickets, although it had no effect on incidence of TD.