William E. Poe

Relationship of whole body and egg essential amino acid patterns to amino acid requirement patterns in channel catfish, Ictalurus punctatus

Abstract 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.

Effects of feeding soybean meal with varying trypsin inhibitor activities on growth of fingerling channel catfish

Abstract Uncooked hexane extracted soybean meal was heated for various lengths of time to produce meals with varying trypsin inhibitor activities. Fingerling channel catfish (Ictalurus punctatus) were fed 25 and 35% crude protein practical type test diets containing soybean meal with graded levels of trypsin inhibitor activity for 10 weeks. Growth rates and protein efficiency ratio (PER) values were reduced in fish fed raw and inadequately heated soybean meal at both protein levels. These effects were more severe at the lower dietary protein level. Growth rates and PER values improved in each study as the trypsin inhibitor activity of the soybean meal decreased to tolerable levels. Fish fed the 35% crude protein diets appeared to tolerate soybean meal with much higher trypsin inhibitor activity than fish fed the 25% crude protein diets. Even though growth rates and PER values were not significantly different over a rather wide range of dietary trypsin inhibitor activities, the best growth rates were not observed at either protein level until about 83% of the trypsin inhibitor activity in the soybean meal had been destroyed.

Apparent digestible protein and energy coefficients of common feed ingredients for channel catfish

Abstract Apparent digestible protein and energy coefficients for corn, cottonseed meal, menhaden fish meal, meat and bone meal, peanut meal, rice bran, rice mill feed, soybean meal and wheat were determined in test diets processed in pelleted and extruded forms in adult channel catfish (Ictalurus punctatus). Test diets were fed ad libitum to fish and fecal samples were collected by the dissection technique. The digestibility value of each ingredient was determined by comparison of the digestibilities of a reference diet and a test diet containing a 70:30 mixture of the reference diet and the test ingredient. In general, the digestibility values determined by this method are higher than previously reported values based on single-source diets which were force-fed to channel catfish. Although some differences were observed in digestible energy values determined on test diets processed in the extruded and pelleted forms, values determined on pelleted test diets appear to be the most reliable in predicting the...

Effect of supplemental phytate and/or tricalcium phosphate on weight gain, feed efficiency and zinc content in vertebrae of channel catfish

Abstract 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.

Effects of dietary cottonseed meal and gossypol on growth of young channel catfish

Abstract Ten isonitrogenous and isocaloric diets containing different percentages by weight of cottonseed ineal or gossypol acetate were fed to age-0 channel catfish Ictalurus punctatus for 8 weeks. Growth was inhibited when fish were fed diets with more than 17.4% cottonseed meal or with 0.09% and greater free gossypol. Fish fed cottonseed meal at 17.4% or greater had higher wholebody concentrations of free gossypol than fish fed lower amounts. Free gossypol in muscle tissue was less than that recommended as safe for human consumption. Free gossypol was most concentrated in liver and kidney tissue. Channel catfish utilized lysine hydrochloride when a diet was supplemented with that amino acid.

Choline nutrition of fingerling channel catfish

Abstract 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.

Evaluation of L-ascorbyl-2-polyphosphate (AsPP) as a dietary ascorbic acid source for channel catfish

Abstract Channel catfish ( Ictalurus punctatus ) fingerlings were fed purified diets containing 0 or 100 mg/kg of ascorbic acid equivalent supplied either by ethylcellulose-coated ascorbic acid, ascorbate-2-sulfate, or L-ascorbyl-2-polyphosphate (AsPP). Fish fed the ascorbate-free diet exhibited external signs of scurvy at 11 weeks. Carcass ascorbate concentrations, histopathology of gill tissue, and radiographs evaluated at the end of the experimental period confirmed that fish fed the ascorbate-free diet were scorbutic. Signs of ascorbate deficiency were not observed in fish fed other diets. Weight gain and carcass ascorbate concentration were highest in fish fed AsPP. Improvement in weight gain and increased tissue concentration of ascorbate in fish fed AsPP is not readily explained, but may related to the resistance of AsPP to oxidation; thus providing a higher concentration of ascorbic acid at absorption sites. The data from the present study demonstrate the efficacy of AsPP in promoting growth and preventing scurvy in catfish.

Studies on the essential fatty acid requirement of channel catfish, Ictalurus punctatus

Abstract 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.

Nitrogen metabolism in channel catfish, Ictalurus punctatus—III. Relative pool sizes of free amino acids and related compounds in various tissues of the catfish

Abstract 1. 1. Free amino acids and related compounds were determined in serum, liver, muscle, gill, gut tract, kidney, heart, brain and spleen tissues of fasting cultured channel catfish. 2. 2. Taurine and ammonia were the major constituents of all tissues studied. 3. 3. In general, the liver and kidney contained the highest concentration, expressed as μmoles/g tissue, of most of the amino acids and related compounds. However, on a per cent distribution of the total pool sizes, the muscle tissue containes by far the largest percentage of almost all compounds studied. 4. 4. Of the protein amino acids, alanine, glycine and glutamic acid were found to be present in the highest concentrations. Contrary to pervious reports, glutamine was not found as the major constituent of the various tissues.

Postprandial changes in serum amino acids of channel catfish fed diets containing different levels of protein and energy

Abstract Five purified diets were utilized to investigate the effect of varying protein and energy intake on postprandial changes in systemic serum amino acid levels of channel catfish ( Ictalurus punctatus ). The diets contained 25, 30 or 35% crude protein at one of three different energy levels. Systemic serum free amino acids and glucose were determined at 0, 2, 4, 8, 12 and 24 h after feeding each diet. In general, for each diet tested, most of the systemic serum free amino acid levels increased within 2 h after feeding, remained elevated for up to 12 h, and returned to fasting levels within 24 h after feeding. Varying the protein to energy ratios in the diets did not profoundly affect postprandial systemic serum free amino acid patterns. There was a significant positive correlation between the levels of systemic serum free essential amino acids and dietary levels. No such correlation was observed for non-essential amino acids. Serine and alanine were the most abundant free amino acids in catfish serum. Glutamic acid, glycine and proline remained relatively low throughout all treatments. A reciprocal relationship was observed between levels of glucose and total free amino acids in the serum.