Factors affecting utilization of niacin and its precursors by chicks

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Animal Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Oduho, George William

Contributors dc:contributor

• Baker, David H.

• Biology, Animal Physiology
• Agriculture, Animal Culture and Nutrition
• Health Sciences, Nutrition

Statement dc:rights

• Copyright 1994 Oduho, George William

Language dc:language

eng

Identifier

AAI9416419
(UMI)AAI9416419

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19296