A 12-week feeding experiment was conducted with fingerling channel catfish ( Ictalurus punctatus ) to determine the effect of supplemental phytate and/or tricalcium phosphate on weight gain, feed efficiency and zinc content in vertebrae. Catfish fed a diet containing 2.2% phytic acid had significantly reduced weight gain and feed efficiency (653 vs 853 and 0.90 vs 1.02, respectively) compared to fish fed a diet containing 1.1% phytic acid. Zinc content in vertebrae was significantly reduced from 132.7 to 59.1 μg/g as the level of supplemental phytic acid was increased from 0 to 2.2% in fish fed diets containing 50 mg zinc/kg diet. Vertebral zinc content was not reduced when phytic acid was supplemented to diets containing 150 mg zinc/kg diet. There was no effect of supplemental tricalcium phosphate on weight gain or zinc content in vertebrae.

Two experiments were conducted to characterize essential fatty acid deficiency in fingerling channel catfish and determine the qualitative requirement of channel catfish for essential fatty acids. Supplementation of 1% ethyl linoleate, 1% ethyl linolenate or 1% ethyl linoleate plus 1% ethyl linolenate to tristearin or ethyl oleate based diets (5% total lipid) did not improve the growth rate of catfish to the level obtained by feeding a 2.5% corn oil plus 2.5% cod liver oil diet during a 12-week study. Fish fed the lipid-free diet or the tristearin or ethyl oleate diets had a higher level of eicosatrienoic acid in their liver polar lipids. The growth rate of catfish was effectively improved by supplementation of 1% n −3 highly unsaturated fatty acids to a tristearin based diet (5% total lipid). These data do not indicate whether linoleic and/or linolenic acid are essential for the catfish; the n −3 highly unsaturated fatty acids appear to be responsible for the enhanced growth.

Channel catfish can apparently utilize dietary methionine to spare, at least in part, their need for dietary choline. In order to determine a choline requirement for channel catfish, it was necessary to use a diet limiting in methionine to induce an increase in liver lipid content indicative of a choline deficiency. A dietary methionine reduction was accomplished by using soybean protein as the protein source in the test diet. An optimal level of 400 mg choline/kg of diet based on liver lipid content was determined for catfish under the dietary conditions used. This value would appear to represent a maximum requirement level because it was determined at the lowest level of dietary methionine that could be used while still meeting the total sulfur amino acid requirement of the catfish. The observations made in this study are consistent with those reported for other animals indicating that fish can synthesize choline from appropriate dietary precursors. Thus, it would appear that many of the differences in requirement values of choline for various fishes reported by previous workers may be explained by species differences in enzyme activities associated with choline synthesis and degradation, as well as, various dietary factors known to directly affect the rate of choline synthesis.

1.1. The amino acid composition of channel catfish eggs and whole body tissue of three different sizes of channel catfish were determined.2.2. Regression analysis indicated a significant correlation between the essential amino acid requirements and the content of the same amino acids in whole body tissue of channel catfish.3.3. A lower correlation was found when the requirement values were regressed against the egg values.4.4. This relationship should serve as a valuable index to evaluate amino acid requirement data as determined by growth studies and to formulate test diets for those species where requirement data are not available.

Abstract: Amino acid analyses of whole‐body, excluding feathers, carcasses of captive eastern wild turkey poults (Meleagris gallopavo silvestris) age 1 to 4 weeks, revealed no major differences in levels of 11 essential amino acids. The most abundant essential amino acids, in descending order, occurred in 3 groups. The first group included leucine, lysine and arginine; the second group valine, threonine, phenylalanine, isoleucine and tyrosine; and the third group was composed of histidine, methionine and tryptophan. Amino acid analyses of insects from 7 orders (Coleoptera, Homoptera, Hemiptera, Lepidoptera, Orthoptera, Hymenoptera and Diptera), and spiders (Arachnida) showed that protein was 76% in spiders and 57% in insects. Amino acid levels and patterns of the Arthropods were similar, and were very similar to the levels and patterns (fingerprints) in wild turkey poult carcasses. Sedge (Carex spp.) and panic grass (Panicum spp.) seeds contained 11.1 and 13.6% protein, while dewberry (Rubus sp.) fruits contained only 6.1% protein. Amino acid levels and patterns varied among the plant items, but there were similarities to turkey poult amino acid patterns. Calculations based on minimum amino acid requirements indicated that a 7‐day‐old poult weighing 70 g, live weight, would have to eat about 12 g, live weight, of insects or 9 g of spiders to meet the minimum amino acid requirements for that 1 day.

A series of studies was conducted to investigate the effects of feeding diets imbalanced with respect to branched-chain amino acids on channel catfish. Basal diets contained casein and gelatin supplemented with crystalline L-amino acids to correspond to the amino acid pattern found in 24% whole egg protein except for the branched-chain amino acids. Basal diets were formulated to be deficient in either leucine, isoleucine, or valine. Excess levels of either leucine, isoleucine, or valine were added to the appropriate basal diet. Growth and feed efficiency data demonstrate that excess leucine depressed growth of fish fed diets deficient in isoleucine or valine, but not in diets adequate in branched-chain amino acids. The deleterious effects of excess leucine could be reversed by supplementation with the deficient amino acid, but not by the other branched-chain amino acid. Growth was also depressed in fish fed excess isoleucine but not valine in leucine-deficient diets. Serum levels of isoleucine and valine suggest that leucine may control the tissue uptake of these amino acids in the channel catfish.

Dead plant material was collected from a tidal marsh, ground to a uniform size (250 pn) and decomposed in vitro at 30°C in darkness for 36 days.Crude protein, total amino acids, and essential amino acids increased from 19.0 to 31.0 mg/g, 11.1 to 17.6 mg/g and 5.8 to 8.1 mg/g respectively from day 0 to day 36.The amino acid and crude protein values observed in the detritus are generally low but the increment during decomposition is considered significant in terms of the marine consumers that depend on highly decomposed detritus for food.

ABSTRACT,Selenium and vitamin E interrelationships in the nutrition of channel catfish (Ictalurus punctatus) were,investigated,in a 26-wk experiment.,A purified basal diet alone or supplemented with 0.2 mg/kg selenium, 50 mg/kg vitamin E or both,was,fed to fingerling channel,catfish in aquaria. Combined,deficiencies of selenium and vitamin E caused suppressed growth, anemia, severe myopathy, exuda tive diathesis and death. Singular deficiencies of either selenium,or vitamin,E did not produce,any of these deficiency signs. Catfish fed selenium-deficient diets with,or without,supplemental,vitamin,E had,reduced,glutathione,peroxidase,activity and elevated,glutathione,transferase,activity in liver. Vitamin,E deficiency,in catfish caused elevated ascorbic acid-stimulated lipid peroxidation of hepatic microsomes, which,was,unaffected,by selenium,supplementation.,The results indicate that there is a significant interaction,between,selenium,and,vitamin,E in the nutrition of the channel catfish. J. Nutr. 116: 1061-1067, 1986. INDEXING KEY WORDS