Factors affecting utilization of niacin and its precursors by chicks
Oduho, George William
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Permalink
https://hdl.handle.net/2142/19296
Description
Title
Factors affecting utilization of niacin and its precursors by chicks
Author(s)
Oduho, George William
Issue Date
1994
Doctoral Committee Chair(s)
Baker, David H.
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Animal Physiology
Agriculture, Animal Culture and Nutrition
Health Sciences, Nutrition
Language
eng
Abstract
Experiments were conducted to study nicotinic acid, nicotinamide, NAD and tryptophan as sources of niacin for the chick. The chicks were fed ad libitum in all experiments. A niacin-deficient diet based upon corn and casein was used to establish growth-promoting efficacy of several sources of niacin activity. In the presence of excess dietary nicotinamide, chicks fed the corn-casein diet achieved maximal weight gain when 100 mg/kg L-tryptophan was supplemented. Weight gain in the linear response surface of the growth curve proved to be a far better measure of niacin bioactivity than tissue accumulation of NAD(P). Multiple linear regression and slope-ratio growth efficacy studies indicated that; nicotinamide in NAD was utilized with an efficiency of 95% relative to nicotinamide used as standard (100%). When nicotinic acid was used as a standard (100%) the relative bioactivity of nicotinamide was 124%; whereas excess dietary tryptophan was 1.94 $\pm$ 0.14% as efficient (wt:wt) as nicotinic acid (52:1) in furnishing bioavailable niacin activity. A niacin-deficient purified amino acid diet that contained adequate (40 mg/kg) or deficient (10 or 15 mg/kg) iron was used to assess the growth promoting efficacy of tryptophan as a niacin precursor. Chicks fed the iron deficient diets had lower ($P<0.05$) hemoglobin than those fed iron-adequate diets. The efficiency (wt:wt) of tryptophan conversion to niacin activity was a mean of 1.77% (56:1) for chicks fed the iron-deficient diet. This was significantly ($P<0.05$) lower than the 2.39% (42:1) efficiency calculated for chicks fed the iron-adequate diet. Thus, iron deficiency reduced tryptophan utilization (for NAD synthesis) but had no effect on nicotinic acid utilization. The results suggest that endemic pellagra in less developed countries results not only from inadequate niacin ingestion but also from subadequate iron ingestion.
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