Foodfish Production Strategies Using 13‐cm and 19‐cm Hybrid Catfish, ♀Ictalurus punctatus × ♂Ictalurus furcatus

Most hybrid catfish, ♀Ictalurus punctatus × ♂Ictalurus furcatus, producers stock 18‐ to 19‐cm fingerlings in single‐batch production. While stocking smaller fingerlings would be less expensive, the economic trade‐offs of using smaller fingerlings is unknown. Two sizes of hybrid catfish fingerlings (13‐cm and 19‐cm) were stocked in single‐size treatments at 9884 head/ha and a multi‐size treatment with each size stocked at 9884 head/ha (total 19,768 head/ha). In the 13‐cm and 19‐cm single‐size treatments, 87 and 98%, respectively, reached market size in one season. In the multi‐size treatment, 77% of all fish stocked reached market size, demonstrating that more than half of the 13‐cm fish reached market size in this treatment. Gross, net, and marketable yields were significantly greater in the multi‐size treatment when compared to the 13‐cm or 19‐cm single‐size treatments, but were not significantly different between the two single‐size treatments. The 19‐cm single‐size treatment resulted in greater break‐even prices and economic risk than the other two treatments. This study demonstrated that 13‐cm hybrid catfish fingerlings can be raised economically in both single‐ and multi‐size production systems in the southern USA.     

Influence of forage fish and dietary lipid supplements on egg quality and fry production in channel catfish (Ictalurus punctatus) × blue catfish (Ictalurus furcatus) hybridization

Hybrid catfish (channel catfish Ictalurus punctatus × blue catfish Ictalurus furcatus) display characteristics that are favourable to aquaculture production. Low hatch percentages are a principal reason this hybrid is not used widely in the catfish industry. This study was conducted to determine whether additional food source rich in lipids may lead to a higher quality egg production. A 10‐week feed trial was conducted in ponds in Auburn, AL. A total of 219 female Kansas Select channel catfish were stocked into nine ponds, 0.04 ha in size. Three dietary treatments were randomly allocated to the ponds. Diet‐1 was a standard 60 g kg^?1 lipid floating catfish feed. Diet‐2 was the same feed supplemented with forage fish at ～28 kg ha^?1. The third diet was the aforementioned catfish feed topcoated with 20 g kg^?1 lipid [10 g kg^?1 menhaden fish oil, 5 g kg^?1 high docosahexaenoic acid (DHA) oil and 5 g kg^?1 high arachidonic acid oil]. Results indicate that brood fish fed the high lipid diet spawned larger egg masses and had larger eggs both in weight and in diameter, with increased complements of fatty acids such as DHA, eicosapentaenoic acid and total n‐3 fatty acids. The neutral and polar lipid fractions are also presented.     

The Costs and Effects of Alternative Winter Feeding Strategies for Channel Catfish Ictalurus punctatus in Multiple-Batch Production

Previous work suggested that feeding catfish, Ictalurus punctatus, more frequently over the winter might reduce weight loss. Twelve 0.10-ha ponds were stocked with 987 kg/ha market-sized fish and 2,960 kg/ha sub-marketable fish in November 2008 with treatments of: (1) unfed, (2) fed daily (fed 90 d), and (3) temperature-threshold feeding (fed 62 d). Total gross yield was significantly greater for the temperature-threshold feeding treatment than the unfed control, but survival and mean weight of fish at harvest were not. Net yield was negative for all treatments, due primarily to mortality of market-sized fish. Plasma glucose and insulin-like growth factor-1 did not differ significantly, but plasma osmolality was significantly lower in fasted than in fed fish. Mean feed consumption rates in vats provided evidence to support more frequent feeding over the winter. Overwintering costs were $0.11/kg with temperature-threshold feeding. Research on strategies to reduce winter mortality has potential to reduce overwintering costs.     

Evaluation of Poultry By‐product Meal in Commercial Diets for Hybrid Striped Bass,Morone chrysops ♀ × Morone saxatilis ♂, in Pond Production

The efficacy of replacing fish meal with petfood‐grade poultry by‐product meal (PBM) on an ideal protein basis in commercial diets for hybrid striped bass (HSB) was evaluated under production conditions in pond culture. A generic production diet (GEN) for HSB was formulated to contain 45% protein, 12% lipid, and 3.7 kcal/kg. Protein in the generic diet was supplied by a mix of animal and plant sources typically used by the industry that included more than 20% select menhaden fish meal and less than 10% PBM. A positive control diet (GEN + AA) was formulated by supplementing the generic diet with feed‐grade Met and Lys to match the level of those amino acids in HSB muscle at 40% digestible protein. Substitution diets were formulated by replacing 35, 70, or 100% of fish meal in the GEN diet with PBM on a digestible protein basis and then supplementing with Met and Lys (designated 35PBM, 70PBM, and 100PBM, respectively) as needed to maintain concentrations equal to those in the GEN + AA diet. Diet formulation and extrusion were conducted by a commercial mill, and all diets met or exceeded known nutritional requirements for HSB. Twenty 0.10‐ha ponds (4 ponds/diet) were randomly stocked with juvenile HSB (76 ± 10 g; mean ± SD) at a density of 7400/ha and fed for 600 d (October 2004 to May 2006). Diets were fed once daily to apparent satiation to a maximum of 95 kg feed/ha. Total weight and number of fish in each pond were determined at harvest. Weight distributions in each pond were estimated by selecting every 15th fish during harvest. Subsets of ten fish from each of these samples were selected randomly for the determination of body composition and nutrient and energy retention. The availability of indispensable amino acids as well as ammonia production from the commercial test diets were determined in separate tank trials. Most production characteristics were not statistically different (P > 0.10) among dietary treatments. Distributions of individual fish weights from each of the ponds were not affected by poultry by‐product level in the diet. Multivariate analysis of body compositional indices grouped diets into two clusters composed of GEN, GEN + AA, 35PBM vs. 70PBM, and 100PBM mainly because fish fed the 70PBM and 100PBM diets had greater (P = 0.001) body fat (visceral somatic indices) than fish fed the other diets. Ammonia production in tanks was not different among diets and peaked 6–8 h after feeding when fish were fed at 1.5% of body weight; ammonia‐N excretion ranged from 197 to 212 mg/kg/d and 18.5–21.5% of nitrogen intake. Some imbalances in the levels and ratios of selected amino acids to Lys were found in the diets containing higher amounts of PBM and were attributed to a lack of accurate availability coefficients during formulation for some dietary proteins. These imbalances in essential amino acids may have been the predominant factor in the somewhat fattier fish observed fed diets containing the two highest levels of PBM. Nevertheless, these results from fish stocked at commercial densities and raised to market size in ponds suggest that formulating diets on an available amino acid basis for all protein sources while balancing limiting amino acids, particularly Met, Lys, Thr, and Trp, on an ideal protein basis will yield significant improvements in HSB performance when fed commercial diets in which all fish meal is replaced with PBM.     

The Effects of Dietary Yeast Culture or Short‐chain Fructo‐oligosaccharides on the Intestinal Autochthonous Bacterial Communities in Juvenile Hybrid Tilapia,Oreochromis niloticus♀×Oreochromis aureus♂

The effects of dietary yeast culture (YC) or short‐chain fructo‐oligosaccharides (FOS) on intestinal autochthonous bacterial communities in juvenile hybrid tilapia, Oreochromis niloticus♀×Oreochromis aureus♂ were studied by 16S rDNA denaturing gradient gel electrophoresis (DGGE). Ninety Tilapias in tanks (10 fish per tank) were randomly and equally divided into three groups. At the end of an 8‐wk feeding period of CK (the control treatment), YC (3 g/kg), or FOS (1 g/kg), autochthonous gut bacteria were analyzed in intestinal samples of all fish in each tank of a recirculating aquaculture system. The clear differences in the banding patterns indicated the obvious effects of dietary prebiotics on intestinal communities in hybrid tilapia. Higher variation was detected within the dietary YC group. This difference might be due to the effects of certain immune‐stimulating agents in YC on the immunity response of hybrid tilapia. It was concluded that dietary prebiotics, YC, and FOS obviously affected the intestinal bacterial community in hybrid tilapia with different patterns for different kinds.     

Experimental Infection of Rainbow Trout,Oncorhynchus mykiss,and Hybrid Striped Bass,Morone chrysops ♂ × Morone saxatilis ♀, with Viral Hemorrhagic Septicemia Virus Genotype IVb

The emergence of a new sublineage of viral hemorrhagic septicemia virus (VHSV) within the Laurentian Great Lakes has caused concern for aquaculture in the United States. Because of the occurrence of VHSV in a new geographic location, new host species have been identified and the complete host range has not been determined. This study confirmed the high resistance of rainbow trout, Oncorhynchus mykiss, to VHSV type IVb infection. In addition, the experimental susceptibility of hybrid striped bass, Morone chrysops ♂ × Morone saxatilis ♀, to VHSV type IVb infection was examined but determined to be highly dependent on age of fish and exposure temperature. No mortality was observed in adult fish infected via intraperitoneal (IP) injection at 15 C, whereas yearling fish infected via IP injection under the same conditions experienced 20.8% mortality. Among yearling fish infected via IP injection, mortality increased to 100% when exposure to VHSV occurred at 10 C. An LD₅₀ for yearling hybrid striped bass exposed to VHSV at 10 C by IP injection was determined to be 1.4 × 10⁴ pfu (SE = 2.1). Thus, at 10 C, yearling hybrid striped bass experience a high mortality when exposed to VHSV IVb by IP injection.     

Low levels of Aflatoxin B1 could cause mortalities in juvenile hybrid sturgeon,Acipenser ruthenus ♂×A. baeri♀

Toxicity of aflatoxin B₁ (AFB₁) was investigated in juvenile hybrid sturgeon Acipenser ruthenus ♂ × A. baeri♀, an important coldwater finfish farmed in China and other countries. Seven experimental diets (Diet A–G) containing different levels of AFB₁ (0, 1, 5, 10, 20, 40 and 80 μg kg^?1 diet) were fed to juvenile sturgeon weighing 10.53 ± 0.17 g kg^?1 to determine its effect on survival, growth, feed consumption, hematocrit, liver histology as well as muscular and hepatic toxin accumulation. The experiment lasted for 35 days and was conducted in two periods of 25 and 10 days each. No external changes or unusual behaviour was observed in the fish fed diets with AFB₁. Mortality was observed in fish fed with highest levels of AFB₁ (80 μg kg^?1– Diet G) from day 12 onwards. After 25 days, fish fed the diet of 80 μg AFB₁ kg^?1 showed significant lower survival (50 ± 5.77%) followed by those fed 40 μg AFB₁ kg^?1 diet (80 ± 5.77%) and 20 μg AFB₁ kg^?1 diet (86.66 ± 3.33%). No significant difference was observed in specific growth rate (SGR) or hepatosomatic index (HSI) between groups. Hematocrit was significantly higher in the fish fed the diet of highest AFB₁. The fish were weighed at day 25 in some treatments (Diets F and G) because of high mortality. However, feeding was continued for another 10 days to observe mortality or behavioural changes if any in the other groups. After 35 days, survival in the fish fed Diet F (40 μg AFB₁ kg^?1) was 40% and those fed Diet E (20 μg AFB₁ kg^?1) was 36.2%. Significant histopathological changes including nuclear hypertrophy, hyperchromasia, extensive biliary hyperplasia, focal hepatocyte necrosis and presence of inflammatory cells were observed in the liver of fish fed high levels of aflatoxin (40 and 80 μg kg^?1). AFB₁ accumulation in fish muscle and liver increased with increased dietary AFB₁ levels. It could be confirmed that 10 μg AFB₁ kg^?1 diet was the maximum allowable level in hybrid sturgeon diet.     

Replacement of Fish Meal with Poultry By‐product Meal as a Protein Source in Pond‐raised Sunshine Bass,Morone chrysops ♀ × M. saxatlis ♂, Diets

Replacement of fish meal (FM) as a protein source with alternative sources of protein in aquaculture diets has been widely explored in aquaculture. The goal of replacement of FM in production diets is to maintain growth, lower production costs, and increase sustainability. Evaluation of the replacement of FM with poultry by‐product meal (PBM) in phase II sunshine bass diets, Morone chrysops × M. saxatilis, was conducted in ponds over 246 d. Four diets were formulated to be isonitrogenous (37%) and isocaloric (4 kcal/g) with different levels of FM replacement with PBM (0, 33, 67, and 100%, Diets 1–4, respectively). Twelve ponds were stocked with 400 phase II sunshine bass (mean weight 5.6 g) and randomly assigned one of the four diets. Fish were fed below satiation based on predicted growth and feed conversion, initially once daily (1700 h) and then twice daily (0700 and 1700 h) as water temperatures and feeding activity increased. Diets were evaluated based on production and performance indicators, body composition, and economic analysis. Production results revealed no significant differences in mean final individual fish weight (511 ± 21 g), net production (4257 ± 247 kg/ha), and survival (85 ± 2%). No significant differences occurred between the performance indicators: mean feed conversion ratio (2.47 ± 0.11), specific growth rate ( 1.84 ± 0.02), and protein conversion efficiency (23 ± 1.3%). Body composition was statistically similar for mean percent fillet weight (49 ± 0.6%) and percent intraperitoneal fat (9.8 ± 1.0%); however, the hepatosomatic index was significantly different between Diets 3 (3.7 ± 0.1%) and 4 (3.2 ± 0.1%). Mean proximate analysis of whole fish (dry weight basis) was not significantly different among treatments yielding the following: percent protein (46 ± 0.4%), lipid (47 ± 1.3%), and ash (8 ± 0.7%). Mean fillet composition (dry weight basis) also revealed no significant differences: percent protein (72 ± 0.8%), percent lipid (30 ± 1.6%), and percent ash (5 ± 0.2%). Proximate analysis was also performed on the diets and revealed a significantly lower protein content in Diet 3 (34.3 ± 0.5%) compared to the other diets (37.1 ± 0.4%). Amino acid analysis of the diets indicated a possible deficiency in methionine in Diets 3 and 4. Based on production, performance, and body composition, the results indicate that complete replacement of FM with PBM in sunshine bass diets is feasible; however, economic analysis suggests that the replacement of FM with PBM may result in reduced revenue over feed costs.     

Chemical Prevention and Treatment of Winter Saprolegniosis (“Winter Kill”) in Channel Catfish Ictalurus puncfatus1

The efficacies of formalin, potassium permanganate, sodium chloride, and copper sulfate as prophylactic treatments for saprolegniosis (“winter kill”) in channel caffish Icralums puncratus were evaluated. Formalin and copper sulfate were also evaluated as postinfective treatments for the disease. Each of the five experiments was conducted with 5–to 7-g channel catfish placed in static water aquaria maintained in refrigerated tanks. Water temperature was reduced from 25 to 10 C within 36 h and maintained at 10 ± 0.5 C for 28 d. Fish were exposed to cultured Saprolegnia sp. at 20 C, and morbidity and mortality data were recorded for 28 d. Saprolegnia sp.-associated mortalities occurred 7–10 d after exposure. Formalin (25 mg/L) was effective as both a prophylactic and postinfective treatment for saprolegniosis. Copper sulfate was effective in preventing saprolegniosis at a concentration of 0.1 mg/L, but was ineffective as a postinfective treatment. Sodium chloride at 5,000 mg/L was effective in preventing saprolegniosis, but was not practical for use in the commercial catfish industry. Potassium permanganate (up to 0.5 mg/L) was not effective in preventing or treating saprolegniosis in channel caffish. Based on the results of this study, it may be possible to prevent saprolegniosis in channel catfish using formalin or copper sulfate during winter when fish are immunosuppressed by rapid decreases in water temperature or to treat infected fish with formalin. However, the routine use of chemicals to control this disease should not be recommended until studies on their efficacy under typical caffish culture conditions and the effect of long-term use of chemicals on fish and on the environment are completed.     

Evaluation of Corn Gluten Feed and Cottonseed Meal as Partial Replacements for Soybean Meal and Corn in Diets for Pond‐raised Hybrid Catfish,Ictalurus punctatus×I. furcatus

This study examined the use of corn gluten feed (CGF) and cottonseed meal (CSM) to partially replace soybean meal and corn in diets for pond‐raised hybrid catfish, Ictalurus punctatus×I. furcatus. Five 28% protein diets containing various combinations of CGF and CSM were evaluated. Fingerling hybrid catfish (mean initial weight: 45 g/fish) were stocked into 25, 0.04‐ha ponds at a rate of 14,826 fish/ha. Fish were fed once daily to apparent satiation for a 179‐d growing season. CGF at 30% of the diet (10% CSM) and a combination of CGF and CSM up to 25% each did not affect physical quality (percentages floatability and feed dust) of the diet. No significant differences were observed in total amount of diet fed, net yield, diet consumption, weight gain, feed conversion ratio (FCR), survival, and fillet proximate nutrient composition among fish fed various diets. Results show that hybrid catfish can utilize CGF at levels up to 30% of the diet (10% CSM), and a combination of CGF and CSM up to 25% each without significantly affecting growth, diet consumption, FCR, and fillet proximate nutrient composition. However, a combination of CGF and CSM at 20% each and above reduced carcass yield.     

Adaptation osmotique a l'eau de mer de differentes especes (Salmo trutta, Salmo gairdneri, Salvelinus fontinalis) et hybride (Salmo trutta ♀ × Salvelinus fontinalis ♂) de salmonides

Spring activation of the gill Na⁺---K⁺-ATPase, osmotic variations after direct exposure to sea-water of high salinity (35.5‰), survival, and growth were studied in three salmonid species reared in France (Salmo trutta, Salmo gairdneri, Salvelinus fontinalis) and in the hybrid tiger trout (♀ S. trutta × ♂ S. fontinalis).The brown trout (S. trutta) studied showed physiological characteristics of smoltification: increase of the gill enzyme activity in fresh-water, rapid control of the osmotic lack of balance after sea-water contact, good growth and survival in summer.Rainbow trout presented characteristics of sedentary species: low values of the gill Na⁺---K⁺-ATPase in fresh-water, and greater and more durable osmotic variations. In spite of a certain degree of euryhalinity in spring and winter, this species suffered significant losses in sea-water during summer.Brook trout appeared as a very stenohaline species unable to survive in sea-water of high salinity; the hybrid presented intermediate characteristics between the two parents.The level of activity of the gill Na⁺---K⁺-ATPase in fresh-water, as well as its evolution after sea-water contact appears as a good indicator of the adaptability of the species to a very hyperosmotic environment, and reveals different strategies for regulating the hydromineral balance, which are discussed.

Résumé

L'activation printanière du système Na⁺---K⁺-ATPasique des microsomes de la branchie chez trois espèces de salmonidés existant en France (Salmo trutta, Salmo gairdneri, Salvelinus fontinalis) et de l'hybride tigre (Salmo trutta ♀ × Salvelinus fontinalis ♂), les modifications osmotiques après transfert en mer de salinitéélevée (35,5‰) et les performances de survie et croissance ont étéétudiées.La truite fario testée se comporte comme une espèce à smoltification: élévation de l'activité branchiale en eau douce, rapide contrôle du déséquilibre osmotique après transfert en mer, bonnes survie et croissance. La truite arc-en-ciel domestique répond comme une espèce sédentaire, avec des valeurs ATPasiques faibles en eau douce, un déséquilibre ionique relativement important à court terme, et plus long à disparaître. En dépit d'un niveau d'euryhalinitéà certaines époques, les mortalités observées sont élevées en été. L'omble de fontaine présente un très faible niveau d'euryhalinité et n'a pas survécu en mer dans les conditions de l'expérience, l'hybride se comporte de façon intermédiaire par rapport aux deux parents.Le niveau d'ATPase en eau douce ainsi que l'augmentation d'activité après transfert paraissent un bon indicateur des facultés d'adaptation de l'animal à un milieu très hypertonique et révèlent des stratégies différentes de régulation de la balance hydrominérale selon les groupes d'espèces envisagés. Tous ces faits sont discutés.     

Performance of Albino and Normal Channel Catfish (Ictalurus punctatus) in Different Water Temperatures

Experiments to determine effects of skin colour on growth in different water temperatures were conducted with albino and normally pigmented channel catfish (Ictalurus punctatus). In Experiment 1, fish were reared in 29°C, 27°C, or 22°C water from hatching to 40 weeks of age. Two additional groups were initially reared in 27°C water for either 12 or 16 weeks and in 22°C water for either the remaining 28 or 24 weeks, respectively. Results indicated that: (1) albino fish reared in 29°C water were superior in growth to normal fish; (2) albino fish did not differ from normal fish in growth when reared in either 27°C or 22°C water; (3) albino fish were inferior in growth to normal fish when reared in 27°C water for either 12 or 16 weeks of the 40-week growth period; (4) genetic differences between families and the age of fish strongly influenced relative growth of both colour types; and (5) both albino and normal catfish were able to compensate in growth at a later age. Experiment 2 began when fish were 48 weeks old and included both albino and normal fish which were either full-siblings or not genetically related. Results indicated that: (1) albinos and normal catfish did not respond differently to a 5°C water temperature change; (2) genetically related and randomly selected albino and normal fish produced consistent results concerning water temperature, skin pigmentation, and sex effects on growth; (3) increasing water temperature from 22°C to 27°C for 19 weeks resulted in increased weight and length of the fish by 144 and 80%, respectively; and (4) growth increase during the first 19-week period resulting from the higher water temperature was followed by a significant increase in the subsequent 10-week growth when the fish were in the lower water temperature.     

HACCP体系在斑点叉尾人工繁殖中的应用

在江西峡江和赣州进行了HACCP(Hazard Analysis and Critical Control Point)体系在斑点叉尾(Ictaluruspunctatus)人工繁殖中的应用研究。应用HACCP的基本原理,对整个斑点叉尾人工繁殖过程进行危害分析,确立了亲鱼培育池的选择、亲鱼种质选择、亲鱼产卵池的选择、受精卵孵化、苗种培育、水质监测、饲料供应、日常管理等8个关键控制点,提出了相应的预防措施、关键限值、监控措施以及超过关键限值时的纠正措施,使各关键控制点处于人为控制之下。实现了斑点叉尾人工繁殖按无公害化、规范化、标准化生产。     

Effects of Dietary Vitamin E Enrichment on Frozen Channel Catfish, (Ictalurus punctatus) Fillets

The storage quality of channel catfish (Ictalurus punctatus), following long term frozen storage, fed diets containing 5 and 10 times the normal level of vitamin E for 45 or 60 days prior to harvest, was evaluated. There were no unusual effects of treatment on fish weight, survival or feed conversion ratios. Muscle vitamin E content was higher (P < 0.05) from fed diets containing supplemental vitamin E than in the control. Oxidation as measured by TBARS and sensory analysis values did not differ (P > 0.05) in response to vitamin E supplementation. Lipid oxidation increased as storage time increased. Lack of change in phospholipid and neutral lipid fractions during storage indicated that autoxidations was the major cause of oxidation in catfish. Vitamin E levels up to 10 times the normal amount did not improve the overall quality of catfish fillets.     

斑点叉尾(鱼回)、团头鲂池塘混养高产试验

在面积为6667 m 2㎡的池塘混养、鲂鱼种,搭配鲢、鳙及银鲫. (鱼回)、鲂及银鲫投喂配合颗粒饲料,鲢、鳙不投饵.设置2台3 kW增氧机,饲养209 d,结果共产鱼6960 kg,团头鲂6889.6 kg,异育银鲫345 kg,鲢、鳙共2137.4 kg,平均产量为2.45 kg/m2,平均成本为11.45 元/m2,平均利润为6.48 元/m2,投入产出比为1∶1.56.     

斑点叉尾鮰、团头鲂池塘混养高产试验

在面积为6667m2 的池塘混养、鲂鱼种,搭配鲢、鳙及银鲫。、鲂及银鲫投喂配合颗粒饲料,鲢、鳙不投饵。设置2台3kW增氧机,饲养209d,结果共产鱼6960kg,团头鲂6889 6kg,异育银鲫345kg,鲢、鳙共2137 4kg,平均产量为2 45kg m2,平均成本为11 45元 m2,平均利润为6 48元 m2,投入产出比为1∶1 56。     

外源核苷酸对斑点叉尾(鱼回)生长及肠道组织发育的影响

以斑点叉尾(鱼回)幼鱼为试验对象,研究不同水平外源核苷酸对其生长和肠道发育的影响.在基础饲料中分别添加0.0%(对照组)、0.02%、0.05%和0.1%的外源核苷酸.结果表明,在斑点叉尾(鱼回)幼鱼日粮中添加外源核苷酸,促生长作用不显著(P>0.05),但可显著促进肠道组织的发育(P<0.05).