| The dietary requirements of riboflavin, niacin and choline for juvenile (fingerlings) channel catfish were reevaluated. The availability of choline in seven common feedstuffs for channel catfish was determined. An enzymatic assay for choline in fish tissue and feed ingredients was developed.;Based on weight gain and nutrient utilization, 6 mg riboflavin/kg diet appeared to be the optimum dietary level for channel catfish. This level was confirmed when the hepatic D-amino acid oxidase (DAAO) activity was used to estimate the riboflavin requirement by broken-line analysis. The dietary niacin requirement for channel catfish fingerlings was estimated to be 7.4 mg niacin per kg diet based on weight gain and was further confirmed by feed and protein efficiency ratio determinations. Weight gain, feed efficiency, liver choline and liver lipid of channel catfish were significantly (P ;A coupled assay was developed linking acetylcholine esterase to choline kinase and pyruvate kinase. The production of adenosine 5;The bioavailability values for choline in cooked corn meal, corn meal, wheat middling meal, soybean meal, cotton seed meal, fish meal and blood and meat meal are 75, 76, 75, 76, 75, 85 and 89%, respectively. The choline available to channel catfish from the typical commercial feeds containing these feed ingredients is more than sufficient to meet the choline needs of this species indicating that dietary supplementation of practical diets is no longer warranted. |
