Niacin - Ruminants - Compendium - DSM
tryptophan will be used for protein synthesis rather than niacin production
An important source of niacin for ruminants is ruminal synthesis
(the conversion of tryptophan to niacin is more efficient [Knox, 1951; Rose and Braidman, 1971; Wertz et al., 1958]). Oral contraceptives that contained high doses of estrogen have also been found to increase conversion efficiency (Rose and Braidman, 1971; Wertz et al., 1958). The priority for body tryptophan utilization is protein synthesis before NAD or NADP synthesis.
The best biochemical measure for estimating the average requirement was judged to be niacin metabolite excretion data, namely the metabolites N1-methyl-nicotinamide and its 2-pyridone derivative. These measures have been reported the most extensively. The niacin intakes that result in these measures being above the levels considered barely adequate represent some degree of body pool reserve. Niacin metabolites are not excreted until adequate tryptophan is available to meet needs for the synthesis of protein, nicotinamide adenine dinucleotide, and nicotinamide adenine dinucleotide phosphate (Fu et al., 1989; Vivian et al., 1958). Metabolite excretion measures are more sensitive to niacin depletion than are other biochemical measures, such as blood levels of pyridine nucleotides or tryptophan. Whereas pellagra is prevented with NEs of about 11 mg/day (at 2,500 kcal/day), restoration of niacin metabolite excretion beyond minimal occurs at intakes of NEs of about 12 to 16 mg/ day. Excretion of N1-methyl-nicotinamide rather than the 2-pyridone derivative is preferred as the target measure for estimating the niacin requirement because this metabolite better differentiates marginal from adequate niacin intakes (Jacob et al., 1989), interpretive guidelines exist for this metabolite (ICNND, 1963), and more data are available for this than for other metabolites.
Niacin | Linus Pauling Institute | Oregon State University
The requirement for preformed niacin as a proportion of the total niacin requirement tends to be lower with higher tryptophan intakes (a greater proportion of tryptophan is available for conversion to NAD once protein synthesis needs are met) and pregnancy
Niacin for dairy cattle: a review - Cambridge Core
Niacin for dairy cattle: a review ..
microbial niacin synthesis in the rumen is an ..
Niacin - Wikipedia
Niacin - Companion animals - Compendium - DSM
Cellular depletion of NAD has been found to decrease levels of the tumor suppressor protein ..
Each peppermint flavoured dose of NiacinMax provides 15mg of niacin
novo niacin synthesis and ..
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