Effects of Feeding Diets with and without Fish Meal on Production of Channel Catfish,Ictalurus punctatus,Stocked at Varying Densities

ABSTRACT

Animal protein, generally fish meal, has traditionally been used in the diet of channel catfish. However, our previous research indicates that animal protein is not needed for growing stocker-size catfish to food fish when the fish are stocked at densities typical of those used in commercial catfish culture. Whether this holds when fish are stocked at high densities is not known; thus, we conducted an experiment to evaluate the effect of feeding diets with and without fish meal to channel catfish stocked in earthen ponds at different densities. Two 32% protein-practical diets containing 0% or 6% menhaden fish meal were compared for pond-raised channel catfish, Ictalurus punctatus, stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48 g/fish were stocked into 30 0.04-ha ponds. Five ponds were randomly allotted for each fish meal level?×?stocking density combination. Fish were fed once daily to satiation for two growing seasons. There was a significant interaction between stocking density and fish meal for net production; net production increased in fish fed a diet containing fish meal compared with those fed an all-plant diet at the highest stocking density, but not at the two lower stocking densities. Net production of fish fed diets with and without fish meal increased as stocking density increased. Viewing the main effect means, weight gain decreased and feed conversion ratio increased for fish stocked at the two highest densities, and survival was significantly lower at the highest stocking density. Visceral fat decreased in fish at the two highest stocking densities. Body composition data were largely unaffected by experimental treatment except for a reduction in percentage filet fat in fish at the highest stocking density, and fish that were fed diets containing fish meal had a lower percentage fillet protein and a higher percentage fillet fat. It appears that at stocking densities two to three times higher than generally used, animal protein (fish meal) may be beneficial in the diet of channel catfish. In regard to stocking densities, high stocking results in higher overall production, but the average fish size decreased as stocking density increased.     

Assessment of a Phytogenic Feed Additive (Digestarom P.E.P. MGE) on Growth Performance,Processing Yield,Fillet Composition,and Survival of Channel Catfish

We investigated the effects of a phytogenic feed additive (Digestarom® P.E.P. MGE) on growth performance, processing yield, fillet composition, and survival of pond‐raised channel catfish. Fifteen 0.4 ha ponds were stocked with 14,820 catfish (126 g/fish) per ha. Fish in control ponds were fed a 32% crude protein commercial floating diet whereas fish in test ponds were fed the same diet supplemented with Digestarom P.E.P. MGE at 200 g/ton. In a second study, ten 0.04 ha ponds were stocked at a similar density with fish that averaged 68 g/fish. At the end of the 6‐mo study, there was no significant difference in the amount of feed fed or the amount of weight gained between the control and Digestarom P.E.P. MGE fed fish. Food conversion ratio, net yield, and survival were also similar between the two groups. Carcass, fillet, and nugget yield were similar. Fillet proximate analysis revealed that fillet fat was lower (P < 0.01) whereas fillet protein tended to be a little higher (P < 0.10) in treated fish. In conclusion, there was a significant reduction in the amount of fillet fat in Digestarom P.E.P. MGE fed fish. Improved fillet composition (higher protein and lower lipid) is of commercial importance.     

Effect of Multiple-batch Channel Catfish, Ictalurus punctatus, Stocking Density and Feeding Rate on Water Quality, Production Characteristics, and Costs

To quantitatively define relationships among stocking densities, feeding rates, water quality, and production costs for channel catfish, Ictalurus punctatus, grown in multiple‐batch systems, twelve 0.1‐ha earthen ponds were stocked at 8,600, 17,300, 26,000, or 34,600 fingerlings/ha along with 2,268 kg/ha of carryover fish. Fish in all ponds were fed daily to apparent satiation using 32% protein floating feed. Temperature and dissolved oxygen in each pond were monitored twice daily; pH weekly; nitrite‐N, total ammonia nitrogen, and Secchi disk visibility every 2 wk; nitrate‐N, chlorophyll a, total nitrogen, total phosphorus, and chemical oxygen demand monthly; and chloride every other month. The costs of producing channel catfish at different stocking densities were estimated. There were no significant differences (P > 0.05) as a result of stocking density among treatment means of (1) gross or net yields, (2) mean weights at harvest, and (3) growth or survival of fingerlings (24–36%) and carryover fish (77–94%). Mean and maximum daily feeding rates ranged from 40 to 53 kg/ha/d and 123 to 188 kg/ha/d, respectively, and feed conversion ratios averaged 1.75. There were no differences in any feed‐related parameter as a result of density. Water quality variables showed few differences among densities at samplings and no differences when averaged across the production season. Yield of fingerlings increased as stocking density increased with significant differences between the two highest and the two lowest stocking densities. Breakeven prices were lower at the higher stocking densities as a result of the higher yield of understocked fish and similar mean individual fish weights produced at these higher stocking densities. Overall, varying stocking densities of fingerlings in multiple‐batch systems had little effect on production efficiency and water quality. Additional research on managing the population structure of carryover fish in commercial catfish ponds may be warranted.     

Comparison of the Channel Catfish,Ictalurus punctatus (NWAC103 Strain) and the Channel × Blue Catfish,I. punctatus × I.furcatus,F1 Hybrid for Growth,Feed Efficiency,Processing Yield,and Body Composition

Abstract

A pond trial was conducted to compare growth, feed efficiency, survival, processing yield, and body composition of the NWAC103 strain of channel catfish, Ictalurus punctatus and the F₁ channel X blue catfish hybrid (CB hybrid), I. punctatus X I. furcatus. Each genotype was stocked into five 0.4-ha earthen ponds at a rate of 14,820 fish/ha. Initial weights were 24.9 and 31.8 g/fish for the NWAC103 strain of channel catfish and the CB hybrid, respectively. Fish were fed a commercial, 28% protein diet once daily to satiation for 160 days. Compared to NWAC103 channel catfish, the CB hybrid consumed more diet, gained more weight, converted diet more efficiently, and had higher net production, survival, carcass yield, nugget yield, visceral fat, fillet moisture and protein, and a lower level of fillet fat. There were no differences in fillet yield and fillet ash concentration between the channel X blue catfish hybrid and the channel catfish. These results suggest that the CB hybrid possesses superior production traits compared with the NWAC103 channel catfish. However, problems of producing a large number of hybrid fingerlings in a cost-effective manner remain to be resolved before the hybrid catfish can be commercially farmed.     

Effect of Dietary Protein Concentration and Feeding Rate on Weight Gain,Feed Efficiency,and Body Composition of Pond-Raised Channel Catfish Ictalurus punctatus1

Two experiments were conducted in earthen ponds to evaluate the effect of dietary protein concentration and feeding rate on weight gain, feed efficiency, and body composition of channel catfish. In Experiment 1, two dietary protein concentrations (28% or 32%) and four feeding rates (≤ 90. ≤ 112, ≤ 135 kg/ha per d, or satiation) were used in a factorial arrangement. Channel catfish Ictalurus punctatus fingerlings (average size: 27 g/fish) were stocked into 0.04-ha ponds at a rate of 24,700 fish/ha. Fish were fed once daily at the predetermined maximum feeding rates for 282 d (two growing seasons). In Experiment 2, three dietary protein concentrations (24, 28, or 32%) and two feeding rates (≤ 135 kg/ha per d or satiation) were used. Channel catfish (average size: 373 g/fish) were stocked into 0.04-ha ponds at a rate of 17,300 fish/ha. Fish were fed once daily for 155 d. In both experiments, five ponds were used for each dietary treatment. Results from Experiment 1 showed no differences in total feed fed, feed consumption per fish, weight gain, feed conversion ratio (FCR), or survival between fish fed diets containing 28% and 32% protein diets. As maximum feeding rate increased, total feed fed, feed consumption per fish, and weight gain increased. There were no differences in total feed fed, feed consumption per fish, or weight gain between fish fed at ≤ 135 kg/ha per d and those fed to satiation. Fish fed the 28% protein diet had a lower percentage carcass dressout and higher percentage visceral fat than fish fed the 32% protein diet. Dietary protein concentrations of 28% or 32% had no effect on fillet protein, fat, moisture, and ash. Feeding rate did not affect FCR, survival, percentage carcass dressout, or fillet composition, except fillet fat. As feeding rate increased, percentage visceral fat increased. Fish fed at ≤ 90 kg/ha per d had a lower percentage fillet fat than fish fed at higher feeding rates. In Experiment 2, dietary protein concentration or maximum feeding rate did not affect total feed fed, feed consumption per fish, weight gain, FCR, or survival of channel catfish. Feeding rate had no effect on percentage carcass dressout and visceral fat, or fillet composition. This was due to the similar feed consumption by the fish fed at the two feeding rates. Fish fed the 24% protein diet had lower carcass dressout, higher visceral fat and fillet fat than those fed the 28% or 32% protein diet. Results from the present study indicate that both 28% and 32% protein diets provide satisfactory fish production, dressed yield, and body composition characteristics for pond-raised channel catfish fed a maximum rate of 90 kg/ha per d or ahove.     

Effect of Dietary Protein Concentration on Growth and Processing Yield of Channel Catfish Ictalurus punctatus1

Abstract.— This study was conducted to evaluate the effect of dietary protein concentration and an all‐plant diet on growth and processing yield of pond‐raised channel catfish Ictalurus punctatus. Four diets were formulated using plant and animal proteins to contain 24%n, 28%, 32%, or 36% crude protein with digestible energy to protein (DE/P) ratios of 11.7, 10.2, 9.0, and 8.1 kcal/g, respectively. An all‐plant diet containing 28% protein with a DE/P ratio of 10.2 kcal/g was also included. Channel catfish fingerlings averaging 40 g/fish were stocked into 24, 0.04‐ha ponds at a density of 18,530 fish/ha. Five ponds were used for each dietary treatment except for the all‐plant diet which had four replicates. The fish were fed once daily to apparent satiation for 160 d. No differences were observed in feed consumption, weight gain, survival, carcass and nugget yield, or fillet moisture and protein concentrations among treatments. Fish fed the 28% protein diet had a lower feed conversion ratio (FCR) than fish fed diets containing 24% and 32% protein, but had a FCR similar to fish fed the 36% protein diet. Fillet yield was higher for fish fed the 36% protein diet than fish fed the 24% protein diet. Visceral fat was lower in fish fed the 36% protein diet than fish fed other diets. Fish fed the 32% and 36% protein diets exhibited a lower level of fillet fat than fish fed the 24% protein diet. The 36% protein diet resulted in a lower level of fillet fat than fish fed the 28% protein diet. There was a positive linear regression in fillet yield and fillet moisture concentration and a negative linear regression in visceral fat and fillet fat against dietary protein concentration. No differences in any variables were noted between the 28% protein diets with and without animal protein except that fish fed the 28% protein diet without animal protein had a higher FCR than fish fed the 28% protein diet with animal protein. This observation did not appear to be diet related since FCR of fish fed the 32% protein diet containing animal protein was not different from that of fish fed the 28% all‐plant protein diet. Data from the present study indicate that dietary protein concentrations ranging from 24% to 36% provided for similar feed consumption, growth, feed efficiency, and carcass yield. However, since there is a general increase in fattiness and a decrease in fillet yield as the dietary protein concentration decreases or DEP ratio increases, it is suggested that a minimum of 28% dietary protein with a maximum DEIP ratio of 10 kcal/g protein is optimal for channel catfish growout.     

Response of Pond‐raised Fingerling Hybrid Catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus,to Dietary Protein Concentrations and Sources

This study examined four experimental diets with different protein concentrations and sources for pond‐raised fingerling hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus. A 35% protein diet with fishmeal was used as the control diet. Test diets were 32 and 28% all‐plant‐protein diets and a 28% protein diet with porcine meat, bone, and blood meal. Small fingerlings with a mean initial weight of 2.9 g/fish were stocked into 20 earthen ponds (0.04 ha) at a density of 172,970 fish/ha. They were fed once daily to apparent satiation for 107 d. No significant differences were observed for total diet fed, gross yield, final weight, survival, or condition factor among dietary treatments. However, fish fed the 28 and 32% all‐plant‐protein diets had a significantly higher feed conversion ratio than fish fed the 35% protein diet with fishmeal. There were no significant differences in chlorophyll a and nitrite concentrations in the pond water, but ponds receiving the 35% protein diet had significantly higher ammonia than those receiving 28% protein diets. Economic analysis suggested potential cost savings by using low‐protein and all‐plant‐protein diets for hybrid catfish fingerling production.     

Evaluation of Various Concentrations of Dietary Protein and Animal Protein for Pond-Raised Channel Catfish Ictalurus punctatus Fed to Satiation or at a Restricted Rate

A factorial experiment was conducted to evaluate effect of dietary protein (28% or 32%), animal protein (0, 3, or 6%), and feeding rate (satiation or >90 kg/ha per d) on production characteristics, processing yield, and body composition of pond-raised channel catfish Ictalurus punctatus . Fingerling channel catfish (average weight: 55 g/fish) were stocked into 60, 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed once daily to satiation or no more than 90 kg/ha per d for 147 d. Fish fed at a rate of >90 kg/ha per d consumed about 85% of the amount of feed consumed by fish fed to satiation. Dietary protein did not affect the total amount of feed fed, amount of feed consumed per fish, weight gain, feed conversion efficiency, or fillet protein. Animal protein had no effect on the total amount of feed fed, amount of feed consumed per fish, weight gain, or fillet protein and ash. Fish fed a diet containing 6% animal protein converted feed more efficiently than fish fed diets containing 0% and 3% animal protein. Fish fed to satiation daily consumed more feed, gained more weight, converted the feed less efficiently, and had a higher carcass yield, a higher level of visceral fat as compared to fish fed at a rate of >90 kg/ha per d. Feeding rate had no effect on fillet protein. Results from this study indicated that both a 28% and a 32% protein diet with or without animal protein provided the same growth rate of channel catfish raised in ponds from fingerlings to marketable size if feed is not restricted below a maximum rate of 90 kg/ha per d. Even though there were some interactions among the three factors evaluated, dietary protein levels of 28% to 32% and animal protein levels of 0% to 6% do not appear to markedly affect carcass yield and fillet proximate composition of pond-raised channel catfish.     

Effects of Dietary Protein and Feeding Rate on Channel Catfish Ictalurus punctatus Production, Composition of Gain, Processing Yield, and Water Quality

A 2 ± 4 factorial experiment was conducted to examine effects of dietary protein level (28, 32, 36, and 40%) and feeding rate (satiation or ± 90 kg/ha per d) on production characteristics, processing yield, body composition, and water quality for pond-raised channel catfish Ictalurus punctatus. Fingerling channel catfish with a mean weight of 64 g/fish were stocked into 40 0.04-ha ponds at a rate of 17,290 fish/ha. Fish were fed once daily to apparent satiation or at a rate of ± 90 kg/ha per d for 134 d during the growing season. Dietary protein concentration had no effect on feed consumption, weight gain, feed conversion, survival, aeration time, or on fillet moisture, protein, and fat levels. Fish fed to satiation consumed more feed, gained more weight, had a higher feed conversion, and required more aeration time than fish fed a restricted ration. Visceral fat decreased, and fillet yield increased as dietary protein concentration increased to 36%. Carcass yield was lower for fish fed a diet containing 28% protein. Increasing feeding rate increased visceral fat but had no major effect on carcass, fillet, and nugget yields. Fish fed to satiation contained less moisture and more fat in the fillets that those fed a restricted ration. Nitrogenous waste compounds were generally higher where the fish were fed the higher protein diets. Although there was a significant interaction in pond water chemical oxygen demand between dietary protein and feeding rate, generally ponds in the satiation feeding group had higher chemical oxygen demand than ponds in the restricted feeding group. There was a trend that pond water total phosphorus levels were slightly elevated in the satiation feeding group compared to the restricted feeding group. However, pond water soluble reactive phosphorus and chlorophyll-a were not affected by either diet or feeding rate. Results from the present study indicate that a 28% protein diet provides the same level of channel catfish production as a 40% protein diet even when diet is restricted to 90 kg/ha per d. Although there was an increase in nitrogenous wastes in ponds where fish were fed high protein diets, there was little effect on fish production. The long term effects of using high protein diets on water quality are still unclear. Feeding to less than satiety may be beneficial in improving feed efficiency and water quality.     

Efficacy of Crystalline Lysine in Alternative Diets for Pond‐raised Hybrid Catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus

A study was conducted to examine the efficacy of crystalline lysine in alternative diets for pond‐raised hybrid catfish, ♀ Ictalurus punctatus × ♂ Ictalurus furcatus. Two 28% protein alternative diets supplemented with l ‐lysine HCl at the required level based on 62% (previously published value) or 100% lysine availability were compared with a traditional 28% protein control diet. Hybrid catfish fingerlings (mean initial weight = 43 g/fish) were stocked into 15 earthen ponds (0.04 ha) at a density of 14,826 fish/ha with five ponds per treatment. Fish were fed once daily to apparent satiation for a 173‐d growing season. There were no significant differences in total diet fed, net yield, weight gain, and survival among dietary treatments. There were also no significant differences in carcass yield, fillet yield, and fillet proximate composition and fillet lysine concentration among treatments. Fish fed the traditional control diet had slightly, but significantly, lower feed conversion ratio than fish fed alternative diets, which is likely related to higher dietary fiber levels in the alternative diets. Results from this study show that crystalline lysine can be considered 100% available when used to supplement lysine‐deficient diets for pond‐raised hybrid catfish.     

Use of Corn Germ Meal in Diets for Pond‐Raised Channel Catfish,Ictalurus punctatus

Corn germ meal (CGM) is a by‐product of corn milling. On the basis of its nutrient composition and digestibility values, it appears to be a suitable ingredient for use in channel catfish, Ictalurus punctatus, diets. A study was conducted to examine the use of various levels of CGM in diets for pond‐raised channel catfish. Four 28% protein diets containing 0, 15, 25, and 35% CGM were evaluated. Fingerling channel catfish (mean initial weight: 71 g/fish) were stocked into 24, 0.04‐ha ponds at a rate of 14,826 fish/ha. Fish were fed once daily to apparent satiation for a 167‐d growing season. No significant differences were observed in total amount of diet fed, diet consumption per fish, net yield, weight gain, feed conversion ratio, survival, fillet yield, and fillet protein, fat, and moisture concentrations among fish fed diets containing various levels of CGM. Carcass yield decreased linearly as dietary CGM levels increased. Depending on prices, CGM can be used interchangeably with corn gluten feed in channel catfish diets as replacements for corn, wheat middlings, and soybean meal to reduce feed cost.     

Production Characteristics, Water Quality, and Costs of Producing Channel Catfish Ictalurus punctatus at Different Stocking Densities in Single-batch Production

Channel catfish Ictalurus punctatus farming is the largest component of aquaculture in the USA. Culture technologies have evolved over time, and little recent work has been conducted on the effects of stocking density on production characteristics and water quality. Twelve 0.1‐ha ponds were stocked with 13‐ to 15‐cm fingerlings (16 g) at either 8600, 17,300, 26,000, or 34,600 fish/ha in single‐batch culture with three replicates per treatment. Fish were fed daily to apparent satiation with a 32% floating commercial catfish feed. Nitrite‐N, nitrate‐N, total ammonia nitrogen (TAN), total nitrogen, total phosphorus, chemical oxygen demand (COD), Secchi disk visibility, chlorophyll a, chloride, total alkalinity, total hardness, pH, temperature, and dissolved oxygen (DO) were monitored. Ponds were harvested after a 201‐d culture period (March 26, 2003 to October 13, 2003). Net yield increased significantly (P < 0.05) as stocking density increased, reaching an average of 9026 kg/ha at the highest density. Growth and marketable yield (>0.57 kg) decreased with increasing stocking density. Survival was not significantly different among densities. Mean and maximum daily feeding rates increased with density, but feed conversion ratios did not differ significantly among treatments (overall average of 1.42), despite the fact that at the higher stocking densities, the feeding rates sometimes exceeded 112 kg/ha per d (100 lb/ac per d). Morning DO concentrations fell below 3 mg/L only once in a 34,600 fish/ha pond. Concentrations of chlorophyll a, COD, nitrite‐N, and TAN increased nominally with increasing feed quantities but did not reach levels considered problematic even at the highest stocking densities. Breakeven prices were lowest for the highest stocking density even after accounting for the additional time and growth required for submarketable fish to reach market size. While total costs were higher for the higher density treatments, the relatively higher yields more than compensated for higher costs.     

Evaluation of Low‐protein Alternative Diets for Pond‐raised Hybrid Catfish,Ictalurus punctatus × Ictalurus furcatus

A study was conducted to evaluate low‐protein traditional or alternative diets for pond‐raised hybrid catfish, Ictalurus punctatus × Ictalurus furcatus. Three 24% protein diets containing decreasing levels of soybean meal (30, 20, and 15%) and increasing levels of cottonseed meal and corn germ meal were compared with a 28% protein control diet. Hybrid catfish fingerlings (mean initial weight = 71 g/fish) were stocked into 20 earthen ponds (0.04 ha) at a density of 14,826 fish/ha with five ponds per dietary treatment. Fish were fed once daily to apparent satiation for a 191‐d growing season. There were no significant differences in total diet fed, net yield, weight gain, feed conversion ratio (FCR), survival, or fillet proximate nutrient composition among dietary treatments (P ≥ 0.10). However, regression analysis showed for fish fed 24% protein diets there was a linear increase in FCR as soybean meal levels decreased (P = 0.06). Compared with fish fed the 28% protein control diet, fish fed 24% protein diets had lower carcass and fillet yield. Results demonstrate a 24% protein alternative diet containing 20% soybean meal may be substituted for 28% protein diets for hybrid catfish during food fish production.     

Effect of Dietary Protein Concentration on Growth and Processing Yield of Channel Catfish,Ictalurus punctatus Raised from Advanced Fingerlings to Large Marketable Size

Abstract

This study evaluated the effects of dietary protein concentration (26, 28, and 32%) and an all-plant protein diet (28% protein) on growth, feed efficiency, processing yield, and body composition of channel catfish, Ictalurus punctatus raised from advanced fingerlings to large marketable size (about 800 to 900 g/fish) for two growing seasons. Fingerling channel catfish (average weight = 56 g/fish) were stocked into twenty 0.04-ha ponds at a density of 18,525 fish/ha. Fish were fed once daily to satiation during the two growing seasons and fed according to recommended winter feeding schedules during the winter. There were no differences in diet consumption, weight gain, feed conversion ratio, survival, processing yields (carcass, shank fillet, and nugget), or fillet composition (moisture, protein, fat, and ash) among fish fed the various diets. These results indicate that a 26% protein diet containing plant and animal proteins or a 28% all-plant protein diet is adequate for channel catfish raised in ponds from advanced fingerlings to large marketable size without adversely affecting weight gain, feed efficiency, processing yield, or body composition. Large marketable-size channel catfish appear to use diets less efficiently but give higher processing yields compared to small marketable-size fish.     

Comparison of Growth, Processing Yield, and Body Composition of USDA103 and Mississippi "Normal" Strains of Channel Catfish Fed Diets Containing Three Concentrations of Protein

Abstract.— This study evaluated the effects of dietary protein concentration (26, 28, and 32%) on growth. feed efficiency, processing yield, and body composition of USDA103 and Mississippi "normal" (MN) strains of channel catfish raised in ponds. Fin-gerling channel catfish (average weight = 32.5 and 47.3 g/fish for USDA103 and MN strains, respectively) were stocked into 24 0.04-ha ponds (12 ponds/ strain) at a density of 18,530 fish/ha. Fish were fed once daily to apparent satiation from May to October 1999. There were no interactions between fish strain and dietary protein concentration for any parameters measured. Regardless of dietary protein concentrations, the USDA103 strain consumed more feed and gained more weight than the MN strain. There were no differences in feed conversion ratio (FCR) or survival between the two strains. Feed consumption, weight gain, FCR, and survival were not affected by dietary protein concentration. The USDA103 strain exhibited a lower level of visceral fat, a higher carcass yield, a lower level of fillet moisture, and a higher level of fillet fat than the MN strain. Regardless of fish strains, fish fed the 32% protein diet had a lower level of visceral fat and a higher fillet yield than fish fed the 26% protein diet. Fish fed the 32% protein diet were also higher in carcass yield as compared to those fed the 28% protein diet. Fillet moisture, protein, and fat concentrations were not affected by dietary protein concentration. Results from this study indicate that the USDA103 strain of channel catfish appears to possess superior traits in growth characteristics compared with the MN strain that is currently cultured commercially. Both strains appear to have the same dietary protein requirement.     

Effect of Stocking Density on Growth and Water Quality for Largemouth Bass Micropterus salmoides Growout in Ponds

Juvenile largemouth bass Micropterus salmoides , trained to accept artificial diets, were stocked into six 0.04-ha ponds at stocking densities of either 6,175 or 12,350 fish/ha. Fish were fed a floating custom-formulated diet, containing 44% protein, once daily to satiation for 12 mo (May 1994–May 1995). At final harvest, the total yield of fish was significantly greater (P < 0.05) and feed conversion ratio (FCR) was significantly lower, for bass stocked at the higher density (4,598 kg/ha and 2.3, respectively) than when stocked at the lower density (2,354 kg/ha and 3.3, respectively). There was no significant difference (P > 0.05) in average weight, length, or survival of bass stocked at the two densities. Averaged over the study period, there were no significant differences (P > 0.05) in total ammonia-nitrogen (TAN), nitrite-nitrogen, or un-ionized ammonia concentrations in ponds in which bass were stocked at the two densities. These data indicate that largemouth bass of the size used in this study are amenable to pond culture at densities of at least 12,350 fish/ha and that higher stocking densities may be possible.     

Effects of available lysine concentrations in 28 and 32% protein diets on growth,feed efficiency,processing yield,and fillet composition of pond-raised channel catfish,Ictalurus punctatus

A study was conducted in earthen ponds to investigate the effects of available lysine (AL) concentrations in 28 and 32% protein diets on production and processing characteristics, proximate composition, and lysine concentrations in the fillet of channel catfish, Ictalurus punctatus. Diets were formulated to contain 28% protein with 1.22 and 1.43% AL, and 32% protein with 1.43 and 1.63% AL, which were equivalent to 4.37, 5.1, 4.46, and 5.1% AL of protein, respectively. Fingerlings with a mean initial weight of 32 g/fish were stocked into 20 ponds (0.04 ha) at 19,760 fish/ha. Fish were fed once daily to apparent satiation for 181 days. No significant differences were observed for total diet fed, net yield, weight gain, survival, or fillet proximate composition among dietary treatments. However, the 28% protein with low AL diet (1.22% AL of diet or 4.37% AL of protein) resulted in significantly lower carcass and fillet yield and fillet lysine level compared with fish fed the 28% protein diet with 1.43% AL (5.1% AL of protein) and 32% protein diets with 1.43 and 1.63% AL (4.47 and 5.1% AL of protein). Results suggest 1.43% AL of diet is adequate for both 28 and 32% protein diets for optimum growth, processing yield, and lysine retention in fillets for pond-raised channel catfish.     

Evaluation of Corn Gluten Feed as a Dietary Ingredient for Pond-Raised Channel Catfish Ictalurus punctatus

Abstract.— This study was conducted to evaluate corn gluten feed as an alternative feedstuff in the diet of pond-raised channel catfish Ictalurus punctatus . Three 32%-protein diets containing 0%, 25%, or 50% corn gluten feed were tested. Channel catfish fingerlings (average weight: 57 g/fish) were stocked into 15 0.04-ha ponds at a rate of 18,530 fish/ha. Five ponds were used for each dietary treatment. Fish were fed to satiation once daily for a 147-d growing period. No differences were observed in feed consumption, weight gain, feed conversion ratio, survival, or fillet protein concentration among fish fed the test diets. Fish fed diets containing 25% and 50% corn gluten feed exhibited a lower level of visceral fat and a higher carcass yield than fish fed the control diet without corn gluten feed. The diet containing 50% corn gluten feed resulted in a lower level of fillet fat and a higher level of moisture than the control diet. There were no visible differences in the coloration of skin or fillet of channel catfish fed diets with and without corn gluten feed. Results from this study indicated that channel catfish can efficiently utilize corn gluten feed at levels up to 50%n without adverse effect on feed palatability, weight gain, or feed efficiency. Corn gluten feed may be beneficial in reducing fattiness of channel catfish and improving carcass yield by reducing the digestible energy to protein ratio of the diet.     

Evaluation of a Barrier Confinement System for Channel Catfish,Ictalurus punctatus,Production

An in‐pond confinement system to separate channel catfish, Ictalurus punctatus, by size within a single pond provides an opportunity for improved growth of understocked fish in ponds with larger market‐sized fish. A barrier of polyvinyl chloride–coated galvanized wire mesh was constructed in five 0.10‐ha earthen ponds to partition the pond into one‐third and two‐third sections, while five other 0.10‐ha ponds were left as traditional open ponds for a control. To evaluate catfish performance in this confinement system, fingerlings (25 g) were stocked at 14,820/ha into the smaller one‐third section of the barrier and carryover fish (408 g) at 2580 kg/ha into the larger two‐third section of the barrier. The control ponds were stocked with the same sizes and numbers of fish in a traditional earthen pond without a barrier. Yield, survival, feed conversion ratio (FCR), growth, and economics were compared between treatments. Fingerling yields were greater in the barrier system that allowed fingerlings to be separated physically from larger carryover fish. There were no differences in yield of carryover fish, survival, FCR, or growth between the control and the barrier ponds. Partial budget analysis revealed a positive net change of $367/ha or $38,125 for a 104‐ha catfish farm (at a market price of $1.54/kg of additional stockers produced). The value of the greater weight of understocked fish produced in the barrier system was greater than the annualized cost of installing the barrier, for farmers raising fish in multiple batch. Thus, on an experimental basis, the confinement system was economically profitable; however, trials on commercial farms are needed to evaluate performance on a larger scale.     

Effects of Stocking Density on Growth of Tilapia nilotica Cultured in Cages in Ponds

Reported maximum carrying capacities of Tilapia nilotica reared in cages are Iow ranging from 10 to 70 kg/m³. This may be related to total numbers of caged fish reared in a body of water and not simply density per cage volume. An experiment was conducted to demonstrate such effects.
Sixteen cages in a 0.77 ha pond were stocked with T. nilotica at either 250, 500, 750, or 1,000 fish/cage for a total of 12,987 fish/ha. One cage in each of four 0.13 ha ponds was stocked with either 250 or 1,000 fish/cage for a total of 1,923 or 7,692 fish/hectare, respectively. Fish were fed a 32% protein diet at equal rates for 169 days. In the 0.77 ha pond, yield per cage was positively correlated with stocking density, while individual mean weights were negatively correlated with stocking density. However, among equal densities per cage between ponds, fish in the 0.13 ha ponds gained about 26% more than in the 0.77 ha pond. An interaction of the effects of density per cage volume and per pond area may have occurred.