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Responses of Nile tilapia in terms of growth, histological anomalies, and biochemical changes to subchronic and toxic concentrations of fumonisin B 1 (FB 1 ) and moniliformin (MON) were evaluated under controlled environmental conditions. Nile tilapia fingerlings (2.7 g) were fed diets containing 0, 10, 40, 70, 150 mg/kg of either FB 1 or MON for 8 weeks. These mycotoxins were obtained from Fusarium moniliforme or Fusarium proliferatum culture materials, respectively. Among tilapia fed diets containing MON, fish fed either 70 or 150 mg MON/kg diet had significantly ( P 1 at levels of 40 mg/kg or higher had significantly lower mean weight gains than the control fish. Mortality was low; differences in percent survival among diets were not observed. Hematocrit was significantly reduced only in fish fed diets containing 150 mg of FB 1 or MON/kg diet. Serum pyruvate levels were significantly higher than control fish for all tilapia fed MON. The ratio between free sphinganine and free sphingosine (SA/SO) in liver increased significantly in fish fed the diet containing 150 mg FB 1 /kg. No histopathological lesions were observed in tilapia fed diets containing either MON or FB 1 . Responses of Nile tilapia in this study to dietary FB 1 and MON demonstrate that both mycotoxins are toxic to tilapia and could reduce the productivity of this fish.

Responses of Nile tilapia to varying concentrations of aflatoxin B 1 (AFB) were investigated under controlled laboratory conditions. Nile tilapia (2.7 g) were fed semipurified diets containing 0, 0.25, 2.5, 10, or 100 mg AFB/kg of diet for 8 weeks. Weight gain and hematocrit of fish fed with 0.25 mg AFB/kg were not significantly different from that of the control; however, diets containing higher levels of AFB had significantly ( P

Earthy-musty off-flavor in channel catfish can adversely affect the catfish industry if strongly off-flavored fish reach the market. Pre-harvest sensory evaluation of fish is commonly performed by processing plants for detecting unacceptable levels of off-flavor. In West Alabama, three to 12 fish are sampled over a period of up to 3 weeks before harvest. Despite this effort, off-flavored catfish regularly reach the market. A study was conducted in summer and fall on ten commercial catfish farms to determine the fraction of off-flavored fish in ponds. Flavor was assessed by sensory evaluation. A larger occurrence of off-flavor was found in summer than in fall. Fraction of off-flavored fish varied from 0 to 54% depending on the pond and the acceptance criterion used. Between-pond variance of the fraction of unacceptable fish was greater than within-pond variance. Therefore, Bayesian sampling should be used instead of conventional sampling based on the binomial function. Different sampling plans are proposed depending on levels chosen for producer and consumer risks. It was recommended to consider a sample size of at least 30 fishes.

Study objectives To determine whether the change in bladder pressure (Pblad) and central venous pressure (Pcvp) may reflect the changes in esophageal pressure (Pes) and gastric pressure (Pgas) when inspiratory pressure support (IPS) is altered. Design Prospective clinical study. Setting The ICUs of a teaching hospital. Patients Ten patients currently receiving IPS ventilation via a tracheostomy or an endotracheal tube who already had bladder and central venous catheters in situ . Measurements and results Airway pressure, Pes, Pgas, Pcvp, Pblad, and flow were measured at the original IPS setting. IPS then was reduced by 5-cm H 2 O increments until IPS was zero or was at the minimum pressure that could be tolerated by each patient. At each level of IPS, pressures and flow were measured at steady-state breathing. The maximum pressure difference for each pressure during inspiration was calculated. We found that the ΔPblad correlated closely with the ΔPgas ( r = 0.904) and that theΔ Pes correlated with the ΔPcvp ( r = 0.951). When the ΔPcvp − ΔPblad was compared with the transdiaphragmatic pressure for each patient as the IPS was altered, the correlation coefficients varied from 0.952 to 0.999. Conclusion Although absolute values for the ΔPcvp during mechanical ventilation do not always reflect the ΔPes, useful information can be obtained from this route. In individual patients, the two sites of measurement followed each other when IPS was changed, enabling a bedside assessment of the response to reducing respiratory support.

A study was conducted to determine if channel catfish yield in ponds can be maintained with reduced feed allowance, while increasing protein concentration in the diet. Channel catfish (Ictalurus punctatus) fingerlings (16.7 g average wt.) were stocked in twenty 400-m2 earthen ponds at a density of 13,750 fish/ha. Diets were prepared to contain three percentages of protein (P) at constant and variable digestible energy (DE) concentrations. One group of diets contained 28%, 32% or 36% protein and a constant level of DE, 3.08 kcal/g of diet. Another group of diets contained the same series of protein percentages and variable levels of DE, 2.70, 3.08 and 3.41 kcal/g, so that DE/P ratio was constant at 9.6 kcal/g. The diet containing 28% protein and 3.08 kcal DE/g diet was the control which was fed at satiation rate. The daily allowance of all the other diets was based upon the amount of protein consumed by the control fish; all treatments received the same daily protein allowance. Therefore, fish fed with the 32% protein diet received 12.5% less feed than the control and those fed with 36% protein diet received 22.2% less than the control. The feeding trial lasted 19 weeks, from June 1 to October 5. When DE level of the diets was constant at 3.08 kcal/g, weight gain of fish was not different (P>0.05) from the 28% protein treatment (satiation fed) and the 32% protein treatment (87.5% of satiation), but weight gain was lower (P 0.05) from the 28% protein treatment (100% of satiation). Feed efficiency ratio (FER) improved (P 0.05) as protein level increased from 28% to 36%, with a 22.2% reduction in feed allowance. There was no difference (P>0.05) in total ammonia nitrogen (TAN), nitrite nitrogen, biochemical oxygen demand (BOD5), chlorophyll a or soluble phosphorus in pond water among treatments; however, TAN, nitrite nitrogen, and BOD5 changed (P

Two 10-week feeding experiments were conducted with channel catfish fingerlings in aquaria to compare the efficiency of utilization for growth of free versus protein bound lysine in practical diets. In experiment 1, a basal, 26% protein diet, deficient only in lysine, was formulated with a combination of peanut meal and corn gluten meal as the primary protein source. The diet was then supplemented with graded levels of lysine by either adding l —lysine · HCl or substituting soybean meal for the peanut meal—corn gluten meal combination to produce two series of diets with increasing concentrations of either free lysine or protein-bound lysine. In experiment 2, the basal diet contained sesame meal as the primary protein source and was supplemented with free or protein-bound lysine as in experiment 1. Slope ratio analysis of response data showed that the efficiency of utilization of protein-bound lysine in soybean meal relative to free lysine from lysine-HCl was 196 and 163% for experiments 1 and 2, respectively, based on weight gain. A subsequent feeding experiment was conducted in which the peanut meal-corn gluten meal basal diet was supplemented with lysine alone or with lysine plus histidine, isoleucine, threonine, and tryptophan to match the essential amino acid composition of the diet in which soybean meal provided the protein. Supplementation of the basal diet with the additional amino acids did not improve fish weight gain relative to that from supplementation with lysine alone. Overfortification of the basal diet with free lysine improved weight gain of fish to equal that obtained with the diet containing soybean meal. Loss of lysine due to leaching of diets in water was 12.7 and 2.0% of the original lysine concentration for free lysine and protein-bound lysine, respectively. When leaching losses are subtracted from the lysine concentrations in the test diets, the efficiency of utilization of protein-bound lysine is still higher than that of free lysine, 175 and 146%, based on weight gain, for experiments 1 and 2, respectively. These results indicate that protein-bound lysine is more efficiently utilized than free lysine in practical type diets for young channel catfish.

A pond feeding experiment was conducted in which Year 2 channel catfish (average initial weight, 61 ± 5 g) were stocked in 400 m2 earthen ponds (13950 fish ha−1) and fed an all-plant extrusion processed commercial type diet that contained 0.20, 0.27, 0.36, 0.44 and 0.60% available phosphorus from plant ingredients and monosodium phosphate. Availability of phosphorus in the basal diet and monosodium phosphate was determined by digestibility (net absorption) trials. All diets contained an inorganic calcium:available phosphorus ratio of 1:1. Each diet was fed to fish in four replicate ponds once daily to satiation throughout a 140 day growing season. Data for weight gain, feed conversion ratio, dressing percentage, serum phosphorus, serum alkaline phosphatase activity, bone ash, bone phosphorus, bone breaking strength, muscle composition and visceral fat were subjected to regression analysis to determine effects of the dietary levels of available phosphorus on these responses. There was no significant effect (P > 0.10) of increasing dietary available phosphorus on weight gain, feed conversion, and dressing percentage. Serum phosphorus, bone ash, bone phosphorus, fat, moisture and protein contents of muscle and visceral fat showed significant linear responses (P < 0.06) and serum alkaline phosphatase activity and bone breaking strength showed significant quadratic responses (P < 0.04) with increasing concentrations of dietary available phosphorus. Broken-line analysis showed that maximum serum alkaline phosphatase activity and bone breaking strength were obtained at dietary available phosphorus concentrations of 0.25 and 0.31%, respectively. Data from this study indicated that an all-plant, commercial type diet with no phosphorus supplement, containing 0.20% available phosphorus, was sufficient for maximum weight gain by channel catfish grown to marketable size in ponds. Based upon alkaline phosphatase activity and bone strength, 0.3% available phosphorus is recommended for production diets for catfish grown in ponds. Increasing the dietary available phosphorus to higher concentrations appears to reduce muscle and visceral fat in intensively-fed, pond-grown channel catfish.

Channel catfish ( Ictalurus punctatus ) fingerlings (average initial weight, 1.70g) were fed casein-based purified diets supplemented with 0, 0.02, 0.06, 0.20 or 0.40 mg of selenium per kg from sodium selenite (Na 2 SeO 3 ), selenomethionine (Se-M) or selenoyeast (Se-Y) for 9 weeks. Data for weight gain and glutathione peroxidase activity were subjected to regression analysis to determine dietary requirements and relative bioavailability for the various selenium sources. Broken-line analysis showed that minimum supplemental dietary selenium requirements as Na 2 SeO 3 , Se-M and Se-Y for weight gain were 0.28, 0.09 and 0.11 mg kg −1 , and for liver glutathione peroxidase activity were 0.17, 0.12 and 0.12 mg kg −1 diet. Relative bioavailability values of Se-M and Se-Y compared to Na 2 SeO 3 were 336 and 269% for growth, and 147 and 149% for glutathione peroxidase activity, respectively. Selenium from Se-M and Se-Y showed significantly higher rates of accumulation in liver and muscle than selenium from Na 2 SeO 3 . This study indicates that selenium allowance in diets of channel catfish can be reduced when selenomethionine or selenoyeast replaces inorganic selenium.

Three trials were performed to identify feed enhancers for largemouth bass. Fish trained on dry pellets were stocked into 45 1 aquaria. Trial 1 evaluated the palatability of diets in which fish meal (FM) was replaced with 0, 20, 40, and 60% soybean meal (SM-00, SM-20, SM-40 and SM-60). Feed intake declined as dietary concentration of soybean meal increased ( P Euphasia pacifica ) extract. Chemical groups were tested alone or in all possible combinations. Nucleotides alone enhanced feed intake of fish by 46% compared with the control diet ( P P > 0.05). No additive effects among chemical groups were observed ( P > 0.05). In trial 3, inosine and IMP-5′ were tested alone at 1400, 2800, and 5600 mg kg −1 of feed or together, each at 2800 mg kg −1 of feed. A diet with 10% fish meal (FM-10) was also evaluated. Effective dietary concentration of IMP-5′ seems to be about 2800 mg kg −1 of feed which gave a feed intake 23% higher than the control diet ( P −1 of feed failed to further increase feed intake ( P > 0.05). Inosine was not an effective feed enhancer at the dietary levels tested ( P > 0.10). No significant additive effect of inosine in a diet flavored with IMP-5′ at 2800 mg kg −1 of feed was found ( P > 0.10). Feed intake was highest for fish fed FM-10 ( P

Year 2 channel catfish averaging 41 g were stocked in 0.04 ha earthen ponds at the rate of 13 750 fish ha−1. When daytime water temperature reached 25 °C, one group of fish (four ponds per group) was placed on restricted feeding for 3 weeks during which time the fish were fed once every 3 days, another group was on restricted feeding for 6 weeks, another group was on restricted feeding for 9 weeks, and another group (control) was on full feeding continuously for the 18 week feeding period. All fish were fed as much as they would consume when placed on full feeding. After 18 weeks, the fish on restricted feeding for 3 weeks weighed approximately the same as the control, in fact, they required only 3 weeks on full feeding to catch up with the control. Fish on restricted feeding for 6 and 9 weeks weighed less (P < 0.05) than the control at the end of the experiment; however, their gains were 90% and 86%, respectively, as much as the control. Feed conversion for the 18 week period was the same for all treatments. Dressing yield and body composition (total fat, protein, moisture) were the same for all treatments at the end of the trial. Immediately following the period of feed deprivation, body fat in all restricted fed fish was lower than in the control fish but within 3 weeks on full-feeding body fat in these fish increased to levels equal to those of the control fish. Muscle fiber diameter was not different among treatments at any period. These results indicate that Year 2 channel catfish in production ponds can partially or completely recover in weight gain and body composition from periods of limited feeding provided they are subsequently fed to satiety.

Year-1 (average 22 g) and year-2 (average 420 g) channel catfish, Ictalurus punctatus, were managed in ponds under three winter feeding regimens: continuous feeding from November 1 through April 23; partial feeding (no feed December, January and February); and no feeding. Weight change, body fat, dressing yield (measured in year-2 fish only), condition factor and muscle fiber size were not significantly different between partially-fed and full-fed fish but were significantly lower in the nonfed fish in both age groups. Nonfed year-1 fish were less resistant to Edwardsiella ictaluri challenge while nonfed year-2 fish were significantly more resistant to E. ictaluri challenge than the two fed treatments. The study indicates that under appropriate management conditions year-1 and year-2 channel catfish not fed during December, January and February may weigh the same in the spring as those fed continuously over winter. The data also indicate that winter or early spring feeding may reduce the resistance of year-2 fish to E. ictaluri challenge; however, more information is needed on this subject before reduced feeding is recommended to control E. ictaluri infection.

The dietary zinc requirements of year-1 channel catfish were determined with an egg-white-based purified diet and with a soybean-meal-based practical diet, each supplemented with serial concentrations of zinc methionine (ZnMet) or zinc sulfate heptahydrate (ZnS). In the egg white diet, supplemental dietary zinc requirements, determined by broken-line regression analysis, for ZnMet and ZnS for maximum weight gain were 5.58 and 18.94 mg/kg, respectively, and for maximum bone zinc deposition were 6.58 and 19.91 mg/kg, respectively. In the soybean meal diet, supplemental dietary zinc requirements for ZnMet and ZnS for maximum weight gain were 5.91 and 30.19 mg/kg, respectively, and for maximum bone zinc deposition were 12.82 and ≥ 80 mg/kg, respectively. The relative bioavailabilities of ZnMet, with ZnS as the standard, were 352% for weight gain and 305% for bone zinc deposition in the egg white diet, and 482% for weight gain and 586% for bone zinc deposition in the soybean meal diet. This experiment showed that ZnMet has approximately 3 times the potency of ZnS in a purified diet and 4–5 times the potency of ZnS in a practical diet containing phytic acid for meeting the dietary zinc requirements of channel catfish.

Year-1 (average initial weight 1.2 g) and year-2 channel catfish (average initial weight 31 g) were fed diets containing various amounts of Fusarium moniliforme corn culture to provide 0.3 (control), 20, 80, 320, or 720 mg of fumonisin B 1 (FB 1 )/kg of diet for 10 and 14 weeks, respectively. Year-1 fish fed 20 mg or more of FB 1 /kg of diet gained significantly less weight than the control and those fed 80 mg or more of FB 1 /kg of diet had significantly lower hematocrits and red and white blood cell counts than those fed lower doses. Mortality among year-1 fish fed 80 mg or less of FB 1 /kg of diet was not significantly different from controls but over 70% of fish fed 320 or 720 mg of FB 1 /kg of diet died during the experiment compared to 0% in controls. Year-2 fish fed 80 mg or more of FB 1 / kg of diet gained significantly less weight than fish fed lower amounts of fumonisin. Dietary concentrations of 320 mg of FB 1 /kg caused significantly lower hematocrit and red cell counts, and higher white cell counts. There were no significant differences in mortalities among year-2 fish fed 80 mg or less of FB 1 /kg of diet, but over 50% of the fish fed 320 mg or more of FB 1 /kg diet died from Cytophaga columnaris infection. Fish fed the two highest doses of FB 1 reduced their food consumption after 1 week and lost weight during the feeding trial. Small (2- to 4-mm diameter) white foci of subcapsular adipocyte hyperplasia were observed in the livers of year-1 and year-2 channel catfish fed 20 mg or more of FB 1 /kg of diet. Livers of year-1 and year-2 channel catfish fed 20 mg or more of FB 1 /kg of diet had swollen hepatocytes with lipid-containing vacuoles, lymphocyte infiltration, and scattered necrotic hepatocytes. These results indicate that diets containing Fusarium moniliforme culture material with FB 1 concentrations of 20 mg/kg or above are toxic to year-1 and year-2 channel catfish.

Fumonisin, a secondary metabolite of Fusarium moniliforme, is frequently found in foods and feeds of humans and animals. Fumonisins are specific inhibitors of sphinganine (sphingosine) N-acyltransferase, a key enzyme in the pathway for de novo sphingolipid biosynthesis and reacylation of sphingosine derived from dietary sources or complex sphingolipid turnover. The objective of this study was to evaluate the effect of F. moniliforme toxins on sphingolipids in year-2 channel catfish. In a 12-week feeding trial, four groups of catfish per treatment were fed pelleted balanced diets containing F. moniliforme cultured corn. The fumonisin B1 (FB1) concentrations in diets were 0.3 (control), 2.5, 5, 10, 20, 40, 80 and 240 mg/kg. The free sphinganine to free sphingosine ratio was significantly (P < 0.05) elevated (with exception of brain) at 10, 20, 40 and 80 mg FB1 per kg diet in kidney, serum, liver and muscle, respectively. The increase in free sphingolipid ratios observed were found to be due to increases in the levels of free sphinganine in tissues. These results demonstrate that a mode of action of F. moniliforme toxins in catfish is similar to other species (ponies, pigs, rats), and is suggestive of fumonisin toxicity. It also demonstrated the potential diagnostic value of ratios of free sphingolipids in catfish.

Channel catfish were fed a semipurified basal diet containing 0, 0.4, or 4.0 mg folic acid/kg with 0, 20, or 200 mg vitamin C/kg in a factorial design in aquaria (29±2°C) for 25 weeks, and growth, survival, and hematological measurements were determined. The remaining fish were overwintered (25 weeks) in circular raceways at ambient outdoor temperature, fed the same experimental diets and challenged with Edwardsiella ictaluri when the water had reached 26°C. Dietary supplementation of folic acid had no effect on any measurement except hematocrit without dietary vitamin C. When the marginal level of vitamin C (20 mg/kg) was fed, hematological measurements increased maximally with the low or high supplement of folic acid (0.4 or 4.0 mg/kg), but weight gain and RBC mean corpuscular volume (MCV) did not respond to folic acid supplementation. When the high level of vitamin C (200 mg/kg) was fed, weight gain improved and MCV decreased maximally with the highest supplement of folic acid. Fish challenged with E. ictaluri showed maximum survival and antibody production when 0.4 or 4.0 mg folic acid/kg was fed with the high level of vitamin C, but only the highest supplement of folic acid improved survival when the diet contained the marginal level of vitamin C. Simultaneous supplementation of both vitamins at the highest levels resulted in the lowest incidence of morphologically abnormal blood cells. These results indicate that the dietary concentration of vitamin C influences the response of channel catfish to different dietary levels of folic acid.

Nile tilapia and channel catfish were grown from fingerling to harvest size with the same commercial diet. The catfish were harvested from a 0.04-h earthen pond at an average size of 610 g and the tilapia were taken from 1-m 3 circular raceways at an average size of 585 g. Both groups of fish were fed to satiation for a 180-day summer feeding period. Twenty fish were randomly collected from each group for determination of processing yield and 10 fish were collected from each group for determination of selected nutrient composition. Processing yield (total fish weight minus weight of head, skin and viscera) was lower for tilapia (51.0% as compared to 60.6% for channel catfish). Fillet yield was also lower for tilapia (25.4% as compared to 30.9%). Fat content of fillet was lower for tilapia (5.7 g/100 g as compared to 7.4 g/100 g). Protein content of fillet was higher for tilapia (20.3 g/100 g compared to 17.3 g/100 g). Caloric value of fillet was lower for tilapia (139 kcal/100 g compared to 144 kcal/100 g). Fatty acid composition of fillet lipids was similar for the two species; monounsaturates comprised an average of 54.6 g/100 g of total fatty acids and n −3 highly unsaturated fatty acids comprised an average of 2.2 g/100 g of total fatty acids. Cholesterol contents of fillet were 31.3 mg/100 g for tilapia and 37.1 mg/100 g for catfish. Amino acid content was similar for the two species. Mineral composition of fillet was similar except that tilapia had higher concentrations of sodium and magnesium and catfish had higher concentrations of potassium and phosphorus.

Two experiments were conducted to evaluate the effect of feeding various lipid sources at high and low water temperatures on responses of channel catfish to challenge (25°C) with Edwardsiella ictaluri. Semipurified diets were fed which contained 7% beef tallow, corn oil, linseed oil, menhaden oil or a 1:1:1 mixture of beef tallow, corn oil and menhaden oil. In Experiment 1, fish (14.3±0.3 g average initial weight) fed the menhaden oil and linseed oil diets for 13 weeks at 28°C had lower survival than fish fed the other diets (P

Future demands on commercial transport aviation require the use of the latest technologies in order to meet performance and economic criteria. These technologies must provide the aircraft with enhanced utility and reduced operating costs in order to provide a competitive edge for the commercial airline companies. This paper presents the chronological development of a carbon fiber reinforced polymeric material technology to be used in primary structures of commercial aircraft. Both the process of the material development and the comparison of significant material property improvements are discussed. Overall, the benefits in integrating the development of the material process, structural design and manufacturing evaluations are demonstrated.

Channel catfish (average initial weight, 156 g) were fed to satiety with a high performance diet (36% crude protein, 3.2 kcal digestible energy/g) containing 0, 20, or 100 ppm of ractopamine in flowing-water raceways for 4 weeks. The fish fed 20 ppm of ractopamine gained 17% more weight (P

Three groups of Artemia , of brine shrimp, nauplii were tested for their effect on growth and survival of hybrid striped bass larvae during a 23-day feeding period (day 5 through day 28 post-hatch). The groups of brine shrimp were a Chinese strain (CH) that had been shown to be sufficient in n -3 highly unsaturated fatty acids (HUFAs) and produced good growth in striped bass larvae, a strain from the Great Salt Lake, UT (GSL) that had been shown to be insufficient in n -3 HUFAs and produced poor growth in striped bass larvae, and the GSL strain enriched with menhaden oil (GSLE) to increase the content of n -3 HUFAs (20:5 and 22:6). The enrichment process involved holding the nauplii for 3 to 9 h in a suspension of menhaden oil in water using gum xanthum as an emulsifier. The growth and survival of larvae fed the GSLE nauplii were equal to those of larvae fed the CH nauplii and significantly greater than those of larvae fed the GSL nauplii. The polar lipids in the larvae fed GSL brine shrimp contained only trace amounts of n -3 HUFAs while the larvae fed the GSLE and the CH brine shrimp contained significant amounts of n -3 HUFAs. The larvae fed GSLE nauplii had higher amounts of n -3 HUFAs in the polar lipids than the larvae fed CH nauplii. These results indicate that brine shrimp which may have desirable hatchability, size or economic traits but are deficient in essential fatty acids can be improved nutritionally by a simple enrichment process using menhaden oil.

Channel catfish (Ictalurus punctatus) fingerlings (1.5 g average initial weight) were fed semipurified diets supplemented with 0, 15, 30, 60 or 120 mg/kg (0, 0.08, 0.16, 0.32, and 0.64 mmol/kg) of ascorbic acid molar equivalent supplied by either Na-L-ascorbyl-2-monophosphate (AAP-Na) or Mg-L-ascorbyl-2-monophosphate (AAP-Mg). After 12 weeks, weight gain was significantly equal for all fish fed AAP-Na or AAP-Mg, although growth rate was less for fish fed the ascorbic acid-free diet (basal). There were no gross signs of vitamin C deficiency in any of the fish fed AAP-Na or AAP-Mg, while spinal deformities were found in 26% of the fish fed the basal diet. Bone collagen content was equal for all treatments with AAP-Na or AAP-Mg; however, there was reduced bone collagen content, a sensitive indicator of vitamin C deficiency, in fish fed the basal diet. Percentage recovery of ascorbic acid from commercially extruded catfish feeds supplemented with AAP-Na and AAP-Mg was 99 (±11.1) and 98 (±12.1), respectively. This study indicates that AAP-Na has equimolar activity to AAP-Mg as an ascorbic acid source for growth and collagen synthesis in channel catfish and that both compounds are highly stable against processing loss. Previous studies had shown that AAP-Mg has equal vitamin potency for channel catfish as L-ascorbic acid.

Two pond-feeding experiments were conducted with channel catfish ( Ictalurus punctatus ), one for second-year fish and the other for third-year fish, in which the fish in 400-m 2 earthen ponds were fed five practical-type diets that contained 24, 28, 32, 36 or 40% crude protein. The diets were similar to those used commercially, with major ingredients being soybean meal, grain products, fish meal, and vitamin and mineral supplements. Protein concentration of the diets was increased by substituting a fixed ratio of soybean meal to fish meal (5 : 1) for corn. Energy concentration of the diets was not regulated. All diets were adequate in essential amino acids on a percentage-of-protein basis. In experiment 1, the fish were fed from an average size of 20 g to 488 g (151 days) at a stocking density of 13 590 fish per ha and in experiment 2 the fish were fed from an average size of 594 g to 1632 g (141 days) at a stocking density of 4942 fish per ha. Each diet was fed in four replicate ponds, once daily to satiation through the growing seasons. Increasing dietary protein concentration had no significant effect on weight gain of second-year fish and a negative linear effect on weight gain of third-year fish. Increasing dietary protein had no significant effect on feed consumption of second-year fish and a negative linear effect on feed consumption of third-year fish. Weight gain was positively correlated with feed consumption in both groups and feed conversion was not significantly affected by the dietary protein concentration. Efficiency of protein utilization decreased linearly as dietary protein increased. Dressing percentage increased as dietary protein increased from 24 to 36% and decreased as dietary protein increased from 36 to 40% in second-year fish, but dressing percentage was not affected by dietary protein concentration in thirdyear fish. In both groups muscle fat decreased linearly, while protein and moisture increased, as dietary protein increased. Second-year fish had lower feed conversion, lower dressing percentage and less muscle fat than third-year fish. The results indicate that second- and third-year channel catfish in highly intensive cultures will gain maximally on feeds containing no more than approximately 24% crude protein with satiate feeding, although muscle fat content will be higher and dressing percentage (of second-year fish only) will be lower with the low-protein diet. Second-year fish have advantages over third-year fish in higher feed efficiency and less muscle fat, but have the disadvantage of lower dressing yield.

Channel catfish, Ictalurus punctatus, were fed 17α-methyltestosterone (MT) or 11-ketotestosterone (KT) at dietary levels of 5 and 32 mg kg−1, and β-estradiol (E2) or 3,5,3′-triiodothyronine (T3) at dietary levels of 5 and 50 mg kg−1 under laboratory conditions. Among all treatments, only the lowest dose of KT produced a significant increase in weight gain over the control. This treatment also caused a reduction in body fat and an increase in body protein. The higher levels of KT and all levels of the other compounds had a neutral to negative effect on weight, protein and fat gains. Fish fed the androgens had broad heads, exophthalmia and dark skin. These fish had enlarged, precociously mature testes while ovaries were not affected. The fish fed E2 or T3 had dark skin, and those fed T3 had broad heads, exophthalmia, and thickening at the base of the fins. The fish fed E2 had degenerated oocytes but testes were not affected. Liver and kidneys of fish from all treatments were examined histologically. In the fish fed E2, the nuclei of many of the hepatocytes were near the sinusoids rather than centrally located as in the control. Vacuolation of epithelial cells of renal tubules in the trunk kidney was found in all treated fish but not in the control.

1. 1. Percentage of triacylglycerols (TG), free fatty acids (FFA) and phospholipids (PL) in the total lipids, the fatty acid composition of each of these lipid classes, and the percentage of cholesterol were determined by gas chromatography in three geographical sources (San Francisco Bay, SFB; Chinese, CH; Colombian, COL) of brine shrim ( Artemia sp.) nauplii. 2. 2. There were no significant differences among sources of brine shrimp in total lipids, TG or FFA with means for all sources of 17.8, 65.8 and 10.9%, respectively. Percentage of phospholipid was significantly higher in SFB and CH sources of brine shrimp, 25.1 and 26.5%, respectively, than in COL 18.3%. 3. 3. Marked differences in percentages of 18:3 ( n -3) (linolenic acid) and 20:5 ( n -3) (eicosapentaenoic acid or EPA) were found among brine shrimp sources, and concentration of these two fatty acids were usually inversely related within sources. The CH source contained higher concentrations of EPA ( > 9.0%) than the COL and SFB sources ( n -3) (docosahexaenoic acid or DHA) was found in any brine shrimp source. 4. 4. Fatty acid compositions of the TG and PL were similar and did not differ among sources of brine shrimp, while the FFA had a lower percentage of polyunsaturated fatty acids, but was similar among sources of brine shrimp. 5. 5. Differences in n -3 fatty acid composition indicated a difference in nutritional quality among sources of brine shrimp for feeding larval fish.

Nine-week laboratory feeding experiments were conducted to evaluate partial substitution of animal protein sources into a 32% protein soybean-meal-corn basal diet for channel catfish (Ictalurus punctatus) fingerlings. In the first experiment, substitution of 5, 10, 20, and 40% menhaden fish meal into the basal diet resulted in increases in weight, protein, and fat gains as fish mean was increased to 20% (P < 0.05), and an increase in fat gain as fish meal was increased to 40% (P < 0.05). In the second experiment, the basal diet was supplemented with 5 and 10% fish meal or isonitrogenous amounts of protein from meat and bone meal (5.6 and 11.3%), blood meal (3.4 and 6.8%), and a 60:40 combination of meat and bone and blood meals (5 and 10%). Weight, protein, and fat gains were improved (P < 0.10) when the lower level of each animal protein, except blood meal, was substituted into the basal diet. Increasing the dietary level of each animal protein, except blood meal, improved gains over those from diets containing the lower level of the animal protein (P < 0.10). Fish meal improved gains more than isonitrogenous levels of the other animal proteins at both dietary levels (P < 0.10). Estimated amino-acid contents of the diets indicate that the increase in growth produced by including fish meal may be explained on the basis of increasing dietary levels of the most limiting amino acids; however, the increase in growth effected by including the other animal protein sources in the diet cannot be explained on that basis. Food consumption during the first 3 days of experiment indicated that inclusion of fish meal, meat and bone meal, or the meat and bone-meal-blood-meal combination improved diet palatability.

Nauplii from five sources of brine shrimp (Artemia sp.) were evaluated for total lipid and fatty acid compositions and subsequently fed to larvae of striped bass, Morone saxatilis. Chinese (CH) and a San Francisco Bay (SFBa) sources were relatively high in 20:5 (n−3), eicosapentaenoic acid (EPA), containing 10.4 and 9.3% (of the lipid), and relatively low in 18:3 (n−3), linolenic acid, containing 3.6 and 3.8%, respectively. Sources from Great Salt Lake (GSL), Colombia (COL), and a second San Francisco Bay source (SFBb) were lower in EPA, containing 1.2, 3.0, and 1.2% and higher in linolenic acid, containing 28.2, 24.2, and 25.2%, than the CH and SFBa sources. Docosahexaenoic acid (DHA), 22:6 (n−3), was not found in any of the brine shrimp. Percentages of total lipids, triacylglycerols, and free fatty acids, were not significantly different among the source.s The larvae were fed nauplii from the five sources of brine shrimp as the first and only food for 12 days (experiment 1) or 17 days (experiment 2). Growth and survival were significantly higher for the larvae fed brine shrimp containing the higher levels of EPA. The slower growth and lower survival of larvae fed brine shrimp high in linolenic acid and low in EPA suggested that striped bass are not capable of elongating and desaturating linolenic acid to longer chain n−3 highly unsaturated fatty acids. These results indicate that striped bass larvae have a dietary requirement for EPA which is in excess of 3% of the dietary lipid or 0.5% of the dry diet, and that variation in EPA content is a major reason for the variation in nutritional quality among brine shrimp sources.

A 3 X 2 factorial feeding study was conducted with channel catfish (Ictalurus punctatus) to evaluate effects of biotin, no biotin, or a biotin antagonist (avidin) in lipid and lipid-free diets. At 10 weeks, fish fed diets containing lipid were significantly larger than fish fed lipid-free diets. At 20 weeks, fish fed diets containing avidin had grown significantly less than those fed the other diets. At 22 weeks, fish fed the lipid diet supplemented with biotin had grown significantly more than those fed the lipid diet without biotin. Fish fed the lipid diet with avidin were found to be anemic and exhibited a marked depigmentation of the skin. Fish fed biotin in lipid and lipid-free diets had higher liver pyruvate carboxylase activity than fish fed diets without supplemental biotin. These results indicate that channel catfish require an exogenous source of biotin for maximum rates of growth and lipid utilization.

A sample from every group of off-flavored channel catfish ( Ictalurus punctatus ) delivered from culture ponds to a commercial processing plant over a 60-day period during the spring-summer growing season was collected for flavor analysis by trained sensory evaluators. Earthy-musty (muddy) type flavors have previously been recognized as the major cause of off-flavors in pond-cultured fish, but in this study other flavors predominated in 75% of the samples. A flavor defined as “sewage” was the dominant flavor in 25% of the samples, “stale” was dominant in 21%, “rancid” was dominant in 8%, and “metallic”, “moldy”, “petroleum”, and “weedy” were dominant in others. Recognizable flavors in addition to the dominant flavor were found in most samples. The earthy-musty flavor was the most distinct and easily recognized and received the lowest (most intense) sensory score. Sewage, stale, and rancid flavors were the most subtle and harder to identify, and received higher (less intense) sensory scores. These off-flavor descriptions should be useful in refining sensory evaluation procedures and developing objective methods for measuring off-flavor in cultured fish.

Channel catfish fingerlings were stocked in 400-m2 earthen ponds at densities of 75 fish per 100 m2 and fed to satiety with diets containing 26, 31, 35 and 39% protein, or 91, 107, 120 and 127 mg of protein/kcal of digestible energy (DE), for 123 days. The diets were similar to those fed commercially, composed of soybean meal, corn, a small amount of fish meal and vitamin and mineral supplements. The protein-to-energy ratio ( P E ) was increased by substituting a fixed ratio of soybean meal and fish meal (5:1) for corn. All diets were adequate in essential amino acids on a percentage-of-protein basis. There was a general increase in live weight, dressed weight, and protein gains as dietary protein increased. Weight gain increased markedly, from 288 g/fish to 407 g/fish, when dietary protein increased from 26 to 31% (P The optimum P E ratio in a soybean meal-fish meal-corn catfish diet for rapid growth, efficient feed conversion and high ratio of protein-to-fat gain appears to be approximately 120 g of protein/kcal of DE. These results show trends in fish responses to variable dietary P E ratios which indicate that the amount of protein in commercial catfish feeds should be chosen on the basis of feed ingredient costs and fish prices.

Several ingredient combinations were processed into flaked diets and evaluated for desirable physical properties. Subsequently, drum-dried flake formulations were prepared and fed to three species of aquarium fish and evaluated for nutritional quality, palatability and color enhancement in the fish. Optimum processing parameters for drum drying flaked diets were determined. Results indicated that flaked diets for aquarium fish, which are palatable, nutritious, water stable, buoyant, crumble resistant and pigment enhancing, can be prepared from relatively inexpensive, simple ingredient combinations by carefully controlling processing parameters with a drum dryer. Functional ingredients are shrimp waste meal, for hydrocolloidal properties; fish meal, for nutritional value and palatability; soybean meal as the primary protein source; grain by-product to supply starch and fiber; fish oil for palatability and water stability; and a concentrated pigment source. Important processing factors are fine grinding of ingredients, optimum solids content of the puree, and minimum heat exposure in drying.

In 1983, pond-cultured penaeid shrimp imported into the United States from culture ponds in Ecuador were found to have an intense earthy-musty flavor which made them unmarketable. High concentrations of geosmin (trans, 1,10-dimethyl-9-decalol), a musty odorous compound, were found in the tail muscle of the shrimp. The level of geosmin, 78 μg/kg muscle, was much higher than levels found in earthy-musty flavored freshwater channel catfish from culture ponds in the United States, which is around 9.8 mg/kg. Cause of the rare occurrence of off-flavor in the shrimp is hypothesized to be reduction in salinity in the coastal culture ponds which allowed growth of geosmin-producing blue-green algae.