Juvenile abalone, Haliotis discus hannai Inc, of initial weight 0.55 +/- 0.02 g, were fed with experimental diets with graded levels of thiamin-HCl (0, 9.8, 18.9, 37.2, 75.9, 150.4 and 309.5 mg/kg diet) for 16 weeks. Thiamin-HCl and other water-soluble vitamins were microencapsulated with sodium alginate by an emulsion coacervation process prior to supplementation. To estimate the thiamin requirement of abalone and to evaluate the thiamin status in this animal, weight gain (WG), daily increment in shell length (DISL), tissue thiamin, thiamin pyrophosphate (TPP), thiamin monophosphate (TMP), transketolase (TKA) and thiamin pyrophosphate effect (TPP-effect) both in viscera and muscle were measured. Except for TMP, all parameters mentioned above responded significantly to the change of dietary thiamin levels in a broken line model. However, growth (WG and DISL), TPP concentrations and TPP-effect both in viscera and muscle were found to be the most sensitive indicators. Based on broken line analyses, the thiamin requirement to satisfy maximum growth was estimated to be 51 mg/kg diet, and the dietary thiamin levels to maximize visceral TPP content and TPP-effect of H, discus hannai were estimated to be 61 and 58 mg/kg diet, respectively. (C) 2002 Elsevier Science B.V All rights reserved.
