Niacin requirement and inability of tryptophan to act as a precursor of NAD+ in channel catfish, Ictalurus punctatus
1997; Elsevier BV; Volume: 152; Issue: 1-4 Linguagem: Inglês
10.1016/s0044-8486(96)01510-4
ISSN1873-5622
AutoresWing‐Keong Ng, Giovanni Serrini, Zhan Zhang, Robert P. Wilson,
Tópico(s)Aquaculture disease management and microbiota
ResumoTwo separate experiments were conducted, firstly to determine the niacin requirement of channel catfish, and secondly to evaluate the efficacy of dietary tryptophan as a niacin precursor. In Experiment 1, purified diets containing graded levels of supplemental nicotinic acid (0, 3, 6, 9, 12, 15, 18, 21 and 24 mg per kg diet) were fed to channel catfish fingerlings for 12 weeks. The dietary niacin requirement for rapidly growing channel catfish was estimated to be 7.4 mg per kg diet. Fish that were fed diets without added niacin demonstrated poor growth, low feed intake, anaemia, lethargy, and mortality when stressed. Liver NAD concentrations increased linearly (r = 0.98) with increasing niacin supplementation in the diet, and did not plateau. In Experiment 2, 10 diets with different supplemental niacin and tryptophan combinations were formulated (niacin:tryptophan), 0:0, 5:0, 10:0, 15:0, 0:250, 0:500, 0:750, 5:250, 10:500 and 15:750 mg per kg diet, and fed to channel catfish fingerlings for 9 weeks. The addition of excess tryptophan in niacin-deficient diets did not significantly (P < 0.05) improve growth rates, feed efficiencies, haematocrits or liver NAD concentrations in channel catfish. Tryptophan is an inefficient precursor of dietary niacin for channel catfish.
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