Effects of niacin deficiency on pyridine nucleotide levels and enzyme activities in various organs of young growing quail.

Three experiments were carried out to determine the effects of feeding a niacin-free diet (NFD) to immature quail. The first two experiments demonstrated that the results were influenced by the age of the birds. Birds placed on test at 4 weeks of age (57 g) had reduced growth rates but did not readily develop niacin deficiency symptoms. In contrast, newly hatched chicks (7.2 g) were highly sensitive as all birds died within 9 days of being fed the NFD. In the third experiment the NFD was fed to birds that were intermediate in weight (19 g) to those in the first two experiments. Niacin deficiency led to a marked depression in growth, closure of eyes, reduced activity and a marked atrophy of the pectoral muscle. There was a dramatic reduction in the level of NAD and NADPH in the pectoral muscle but not in other tissues. The niacin status of quail did not affect the activity levels of metabolically related or unrelated enzymes in liver or pectoral muscle. It may be concluded that niacin deficiency reduces pyridine nucleotide levels in muscle tissue but not other tissues and that it does not affect the activity level of certain enzymes in muscle or liver tissue.