Rainbow Trout Fingerlings Research Articles

The Effect of Dietary Carnitine Supplementation on Growth of Rainbow Trout Fingerlings

The Effect of Dietary Carnitine Supplementation on Growth of Rainbow Trout Fingerlings

Tissue distribution and structure of barrier cells in the hematopoietic and lymphoid organs of salmonids.

Barrier cells have been recognized as a discrete group of fibroblastic- or myofibroblastic-like cells located in the lymphoid and hematopoietic organs of mammals. This paper reports the results of a morphological study of the main lymphoid organs of three salmonid species, in which cells structurally similar to the mammalian barrier cells were observed in healthy animals. The spleen, kidney, and thymus of fingerlings of rainbow trout, Oncorhynchus mykiss, and Coho salmon, Oncorhynchus kisutch, and of adult brown trout, Salmo trutta fario, were processed for electron microscopy study using various fixation methods. Semithin sections were used for the Periodic Acid-Schiff (PAS) staining technique, and for the demonstration of the endogenous peroxidase activity. The kidney and spleen of all the species contained a variable, but usually low, number of electron-dense, elongated, and branched cells, ultrastructurally similar to the mammalian barrier cells. They also occurred in the thymus of some brown trout and Coho salmon, but not of rainbow trout. The electron density of this cell type was present after the various types of fixation procedures. They show numerous ribosomes, well-developed secretory organelles, electron-clear vesicles, large granules, and microfilaments. In all the salmonid species, barriers cells were positive for PAS staining and for endogenous peroxidase activity. A small number of barrier cells were in mitosis. In the different organs barrier cells appeared as isolated cells, or forming syncytial networks. They were found lining the blood sinusoids of the splenic red pulp and of the renal hematopoietic tissue, in the periellipsoidal sheaths, and closely associated with erythropoietic and plasmacytopoietic foci. Our results demonstrate the presence of cells closely resembling mammalian barrier cells in the hematopoietic and lymphoid organs of salmonids. The structure and tissue distribution of the salmonid barrier cells are discussed in relation to the functional roles described for this cell type in mammals.

Intraperitoneal injection of sulfur amino acids enhance the hepatic cysteine dioxygenase activity in rainbow trout (Oncorhynchus mykiss)

As part of the investigation into cysteine metabolism in fish, sulfur amino acids and their derivatives were injected intraperitoneally to fingerling rainbow trout (Oncorhynchus mykiss) to examine how the doses of these compounds affect the hepatic cysteine dioxygenase [EC 1.12.11.20] in this species. A dose of 0.25 mmol L-cysteine per 100 g body weight induced the enzyme activity as much as 2.5 times that of the control fish within 4h after the injection. The activity increased proportionally to the increasing dose of cysteine up to the dose of 0.15 mmol per 100 g body weight. The induction was observed to be rather specific to L-cysteine. These findings suggested that the cysteine sulfinate pathway might play an important role in the metabolism of excess cysteine in rainbow trout. The dosage of L-cysteine larger than 0.50 mmol per 100g body weight led to mortality of the fish. The pathway of cysteine catabolism was considered to function to prevent toxic accumulation of cysteine in rainbow trout, as in the case of mammals.

Assessment of Demand Feeder Spacing on Hatchery Performance, Fin Condition, and Size Variation of Rainbow Trout Oncorhynchus mykiss

Abstract.— Fingerling rainbow trout, Oncorhynchus mykiss, were fed for 133 d by one of three feeding methods: one demand feeder per 5.5 m of raceway, 2 demand feeders per 5.5 m of raceway, and hand‐fed controls. Mean weight, total length, mortality, and feed conversion were not influenced by the method of feeding. Size variation did not differ among treatment groups, as assessed by comparing the coefficient of variation of total length. Necropsy‐based health and condition profiles were conducted three times during the rearing period, and results indicated that fish were generally normal and healthy in all treatments. Several parameters differed significantly over time, but no trends were observed except for the fin index and hematocrit. Over time, hematocrit decreased from 48.6 to 45.0%, and the fin index increased from 0.80 to 1.57. Fin index values did not differ among the feeding methods. Fin condition assessed by measuring relative fin length was better in the single feeder treatment than controls for caudal and ventral fins in the last sample. However, since fish from the two‐feeder treatment did not differ from controls, demand feeding per se did not improve fin condition relative to fish that were fed by hand, four to six times per day. The lack of significant improvements in growth or health with the addition of another demand feeder indicated that using more than one feeder per 5.5 m of raceway length is unnecessary for culture of juvenile rainbow trout.

Flow cytometry measurement of mixed function oxidase activity and cell viability in rainbow trout (Oncorhynchus) hepatocytes: Method development

A short-term assay procedure was developed measuring mixed function oxidase (MFO) activity and cell viability in primary hepatocytes cultures of rainbow trout (Oncorhynchus mykiss), using flow cytometry. Assays to measure the reaction rate of MFO utilized live hepatocytes (50 × 104 cells · mL−1) incubated at 22°C in the presence of 5(6)methoxycarbonyl fluorescein methyl ether methyl ester (MCF) substrate. Results of these experiments enabled optimal enzyme-substrate reaction conditions to be fixed at 30 μM MCF for a 20 min period. Hepatocytes were also subjected to cell volume changes by varying their buffer medium osmolarities. It was shown that the fluorescence intensity of propidium iodide, an indicator of cell viability, was influenced by cell volume, but that MFO-related fluorescence intensity was unaffected. Other experiments indicated that simultaneous flow cytometric analysis of cell viability and MFO activity is possible, as long as interference of MFO activity fluorescence emission on cell viability fluorescence emission can be resolved. Exposure of hepatocytes (48 h, 15°C) to β-naphthoflavone and benzo-[a]-pyrene (known inducers of fish cytochrome P-450 detoxification systems) resulted in significant expression of MFO activity under the experimental conditions described. Further validation of the end points measured with this procedure is in progress and involves comparisons with similar end points (96 h LC50 and 7-ethoxyresorufin O-deethylase activity) determined with fingerling rainbow trout exposed to industrial wastewaters. © 1996 by John Wiley & Sons, Inc.

Non-essential amino acid sources in crystalline amino acid diets for trout (Oncorhynchus mykiss)

A study was conducted over a 84-day period to evaluate glycine, L-glutamic acid and L-glutamine as sources of non-essential amino acids (NEAA) in dietary ‘protein’ consisting of crystalline amino acids only. The study was performed with a total of 1200 rainbow trout fingerlings (Oncorhynchus mykiss) of 48 g mean body mass. The addition of non-essential amino acids (NEAA) to essential amino acids (EAA) evidently improved growth and feed efficiency: glutamine was superior to glycine and glycine superior to glutamic acid. However, the best results in growth were obtained by adding a mixture of all three NEAA. The improvement of trout performance by glutamine may hypothetically be traced back to a better amino acid absorption capacity by a less acidic intestinal milieu. In consequence, the optimal EAA to NEAA ratio may have to be redefined.

Response threshold levels of selected organic compounds for rainbow trout (Oncorhynchus Mykiss)

AbstractThe responses of 27 organic compounds, mainly chloromethanes, ‐ethanes, ‐ethenes, and ‐phenols, were investigated by exposing rainbow trout fingerlings to low microgram‐per‐liter concentrations in a darkened flow‐through system for up to 1 h. Responses by the fish were followed continuously by observing ventilation rates (frequency and amplitude), swimming patterns, and general activity using the low‐voltage electric fields generated by the fishes' activity. The lowest level of response was found for trichloroethylene at 5 μg/L. Dichloromethane, 1,1‐ and 1,2‐dichloroethane, 1,1,1‐ and 1,1,2‐trichloroethane, cis‐1,2‐dichloroethylene, 1,3‐dichloropropene, and allyl acetate were responded to at concentrations of 10 μg/L, carbon tetrachloride at 15 μg/L, and 4‐chlorophenol and 2,4‐dichlorophenol at levels of 30 μg/L. Unsubstituted phenol was not responded to at levels of up to 50 μg/L.

Experimental use of cobble substrates in concrete raceways for improving fin condition of cutthroat ( Oncorhynchus clarki) and rainbow trout ( O. mykiss)

In two separate experiments, Bear Lake cutthroat trout ( Oncorhynchus clarki Utah) fingerlings and domesticated rainbow trout ( O. mykiss) fingerlings were reared for 10 and 6 months, respectively, in concrete raceways with or without (controls) cobblestone bottoms. Health/Condition Profiles (HCPs) were performed bi-monthly on 20 fish per treatment. Both species showed significantly reduced fin erosion in cobble bottom raceways using fin scores from all 8 fins of individual fish. Relative fin lengths (% of body length) showed that significant shortening of fins of control fish occurred on caudal and both pectoral fins for cutthroat trout and for right pectoral, both ventral, caudal, and anal fins of rainbow trout. Comparison of the two species for relative fin lengths and fin scores showed that fin erosion was much more severe in rainbow trout. Overall, cobble substrates reduced fin erosion for both species, suggesting that natural bottoms are better for rearing than concrete.

The Effcet of Combined Use of Several Alternnative Protein Sources in Fingerling Rainbow Trout Diets

A feeding experiment was conducted to investigate the effect of combined use of several alternative protein sources for fish meal in diets for fingerling rainbow trout Oncorhynchusmykiss. In the control diet, brown fish meal (BFM) was used as the sole protein source to provide 40% crude protein. In the test diets, 60 or 80% of the BFM protein in the control diet was isonitrogenously replaced by several combinations of soybean meal (SBM), meat meal (MM), malt protein flour (MPF), corn gluten meal (CGM), and dried brewer's yeast (DBY). These diets were fed to the fish with an initial mean weight of 9.4g for 6 weeks at 16°C. Combinations of SBM and MPF, SBM and CGM, and MM and MPF at the 60% replacement level improved the weight gain, feed efficiency, and protein retention of the fish relative to the replacement of BFM by SBM or MM alone, and there were no significant differences in these values between the combination group and the control group. Combined use of SBM, MM and MPF at the 60% replacement level showed similar growth and feed performances to the above mentioned SBM and MPF, or MM and MPF diets, however, the performances at the 80% replacement level were inferior.Addition of DBY to the 80% replacement level diet improved the weight gain to the same level attained by the control group. These results suggest that the combined use of two alternative sources such as SBM and MPF, SBM and CGM, and MM and MPF improve rearing performance of fingerling rainbow trout as cornpared with the use of SBM or MM alone, and that the combined use of SBM, MM, MPF, and DBY at a proper ratio can substitute the 80% of BFM protein.

Morphological changes in rainbow trout (Oncorhynchus mykiss) gill epithelia following repeated intermittent exposure to chloramine-T

Chloramine-T is a widely used prophylactic and therapeutic agent in freshwater aquaculture. This study examined the effects of repeated intermittent exposure of healthy rainbow trout (Oncorhynchus mykiss) fingerlings to sublethal concentrations of chloramine-T (0, 5, 10, or 20 mg/L) twice weekly in 1-h pulses at 11 °C for 4 weeks in a replicate-tank facility. Gills were excised from subsamples of fish prior to exposure and at the end of the 4-week experimental period. Tissue was fixed and processed for light microscopy and transmission and scanning electron microscopy. The gill epithelium from fish treated with 10 and 20 mg/L chloramine-T appeared swollen and vacuolated, with extensive intercellular edema. There was a significant reduction in the number of lamellar mucous cells and an apparent increase in the numbers of chloride cells. Chloride cells from both the base of the lamella and the lamellar surface of gills exposed to chloramine-T had a significant increase in the area of the apical plasmalemma after treatment with 10 and 20 mg/L, and a reduction in the thickness of the apical plasmalemma-associated glycocalyx. These morphological changes are consistent with a compensatory mechanism for the remedial uptake of ions, suggesting that chloramine-T increased epithelial ion permeability coincident with a possible influx of water leading to intercellular edema. Chloride cell proliferation and intercellular edema may also have affected gas exchange across the branchial epithelium.

Cytopathology of liver and kidney in rainbow trout Oncorhynchus mykiss after long-term exposure to sublethal concentrations of linuron

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 21:35-52 (1995) - doi:10.3354/dao021035 Cytopathology of liver and kidney in rainbow trout Oncorhynchus mykiss after long-term exposure to sublethal concentrations of linuron Oulmi Y, Negele R-D, Braunbeck T ABSTRACT: Hepatic and renal cytopathological alterations in fingerling rainbow trout Oncorhynchus mykiss following 5 wk exposure to 30, 120, and 240 ug l^(-1) linuron [3(3,4-dichlorophenyl)-1-methoxy-1-methylurea] were studied by electron microscopy. Ultrastructural alterations were detected in liver and kidney at >=30 ug l^(-1), 2 orders of magnitude below conventional LC_(0). The response suggested a dose-response relationship with a change from adaptive to degenerative features at 120 ug l^(-1). Hepatocyte changes included: stimulation of mitosis; segmentation of nuclei; partial reorganization of heterochromatin; multiplication of nucleoli; fractionation, vesiculation and transformation of rough endoplasmic reticulum (RER) into myelinated bodies; induction of smooth endoplasmic reticulum; moderate steatosis; apparent proliferation of mitochondria, peroxisomes, Golgi fields and lysosomal elements; depletion of glycogen; perisinusoidal lipid accumulation; elevated rate of hepatocytes in various stages of necrosis; infiltration and increased phagocytic activity of macrophages. Reactions of renal tubular cells were differentiated in different nephron segments. Major alterations by site in kidney were (1) renal corpuscle: lobulation of podocyte nuclei; (2) proximal segment I: elevated heterogeneity of all cell components, increased heterochromatin and nuclear size, rearrangement of RER, proliferation of Golgi fields, novel lysosomal elements, decreased mitochondria and lysosomes at 240 ug l^(-1); (3) proximal segment II: nuclear lobulation, binucleated cells, proliferation of lysosomes and peroxisomes (lower concentrations), decreased peroxisomes and mitochondria (240 ug l^(-1)), crystalline inclusions in lysosomal matrix, fragmentation, degranulation and circular arrangement of RER; (4) distal segment: induction of giant mitochondria with longitudinal crystalline inclusions, atypical lysosomes with long crystalline matrix inclusions, and augmentation of various lysosomal elements. Comparison of linuron-induced cellular alterations with cytopathological effects by potential linuron breakdown products, namely 4-chloroaniline and 3,4-dichloroaniline, revealed a high degree of similarity of cytopathological phenomena, indicating that part of the changes observed after linuron exposure might well be due to the action of linuron metabolites. KEY WORDS: Rainbow trout . Liver . Kidney . Ultrastructure . Linuron . 4-Chloroaniline . 3,4-Dichloroaniline . Cytopathology Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 21, No. 1. Publication date: February 02, 1995 Print ISSN:0177-5103; Online ISSN:1616-1580 Copyright © 1995 Inter-Research.

Combinational Use of Malt Protein Flour and Soybean Meal as Alternative Protein Sources of Fish Meal in Fingerling Rainbow Trout Diets

Combinational Use of Malt Protein Flour and Soybean Meal as Alternative Protein Sources of Fish Meal in Fingerling Rainbow Trout Diets

Tissue Distribution of Enrofloxacin in Fingerling Rainbow Trout Oncorhynchus mykiss Following Different Doses of Oral Administration

AbstractRainbow trout Oncorhynchus mykiss were fed a ration medicated to provide enrofloxacin (Baytrilo®, Bayer) at 2.5, 5.0, or 10.0 mg drug per kg fish per d either 5 or 10 d. Tissue Concentrations of enrofloxacin were measured in liver, kidney, muscle, skin, and serum during the medication period, and thereafter for a total of 30 d. Highest tissue concentrations were observed in fish medicated with 5 mg enrofloxacin per kg fish per d for 10 d. Tissue concentrations of anitmicrobial activity were found to exceed minimum inhibitory concentrations of enrofloxacin for several isolates of Aeromonas salmonicida and Renibacterium salmoninarum. Lower than expected tissue concentrations were observed for the 10 mg per kg fish per d doses, perhaps due to a lack of acceptance of the medicated ration. The results support evaluation of a 5 mg per kg fish dose to treat bacterial infections of salmonids under field conditions.

The effect of oral administration of flavophospholipol in rainbow trout ( Oncorhynchus mykiss) fingerlings

The effect of oral administration of flavophospholipol in rainbow trout ( Oncorhynchus mykiss) fingerlings

Requirement of Rainbow Trout for Dietary Phosphorus and Its Relationship to the Amount Discharged in Hatchery Effluents

Fingerling rainbow trout Oncorhynchus mykiss with initial mean weights of 9 g (small fish) and 35 g (large fish) were fed diets adequate in all known nutrients except phosphorus (P). In two experiments, triplicate lots of rainbow trout were fed basal diets containing either 0.14 or 0.41% non-phytin P, with or without graded levels of supplemental P. Deficiency of P reduced growth, feed efficiency (weight gained/weight fed), bone ash, and whole-body ash contents. The requirement for non-phytin P by small trout for maximum growth and feed efficiency was not more than 0.41% of diet: The requirement by large trout was between 0.34 and 0.54% of diet. The requirement of non-phytin P for maximum bone ash development was about 0.51% of diet for small trout and more than 0.54% for large trout. Whole-body phosphorus content of small trout suggested a requirement above 0.51% but not more than 0.61% non-phytin phosphorus. Although an effect of size of trout on the requirement was not clearly demonstrated, these results show that trout required more dietary P for bone mineralization than for weight gain. The minimum dietary requirement for non-phytin P for bone mineralization was probably between 0.54 and 0.61% of diet. Discharges of P into effluent water increased significantly as trout were fed increasing levels of P. When trout were fed 0.61% available P, approximately 67% of P consumed was retained, and discharges of soluble P in effluents were 2.0 g P/kg weight gain or 1.8 g P/kg feed fed.

Effect of temperature and feed ration on energy utilization in large rainbow trout, Oncorhynchus mykiss (Walbaum)

Abstract In one experiment, temperature and feed ration were varied for rainbow trout, Oncorhynchus mykiss (Walbaum), with an initial size of about 1200g. In two experiments the feed ration was varied between parallel tanks, with naturally fluctuating ambient temperatures, and containing rainbow trout with an initial size of about 1000g and 400–550g, respectively. Growth and feed efficiency were measured in all experiments. An ad libitum feed ration without wastage produced the most effective energy utilization in most experimental groups. At best an average of 50% of the gross energy was utilized for growth. The relation between growth rate and feed ration was linear, and there was no optimum point for feeding below this level. The observed intake of energy is compared with growth, measurements of digestibility, feeding and starving metabolism. It is also linked to earlier observations of intake by rainbow trout fingerlings to give equations expressing the energy needs of rainbow trout of different sizes (30–1500g). These are intended to be used for efficient rearing at different temperatures (10–22°C).

Utilization of Malt Protein Flour in Fingerling Rainbow Trout Diets

Two feeding experiments were conducted to evaluate malt protein flour (MPF) as an alternative protein source for the diet of rainbow trout Oncorhynchus mykiss fingerlings. MPF is a new protein rich by-product from brewer's spent grain. Experiment 1 was conducted to clarify the suitable substitution level of MPF for white fish meal (WFM) in the diet. The control diet, containing WFM as the sole protein source, and isonitrogenous (40% crude protein) experimental diets, containing MPF substituted for 20 to 80% of WFM protein, were fed to fish with an average initial weight of 10g for 6 weeks. Weight gain and feed efficiency in fish fed the diet substituting MPF up to the 60% level were not different (p>0.05) from those in fish fed the control diet. There were no significant differences in protein and energy retention between 0 to 40% substitution level. In Experiment 2, crystalline essential amino acids (EAA) were supplemented in the diets containing MPF to simulate the EAA composition in the control diet. Consequently, no significant differences were detected in protein and energy retention between 0 to 60% substitution level. Thus, these results suggest that MPF is a promising alternative protein source for the diet of fingerling rainbow trout.

Effect of feeding schedule on growth of rainbow trout

Rainbow trout (Oncorhynchus mykiss) fingerlings were reared for 2 months under one of two different feeding regimes (‘one and two diurnal peaks’) and under a constant feeding regime as a control in order to find out if it is possible to fit the feeding to the assumed circadian rhythm. The differences in the specific growth rates observed between the different feeding treatments were not significant, but the ‘tank-effect’ and the effect of the genetic background of the fish were highly significant. The conclusion that no beneficial effects are achievable through alteration of the feeding regime and the significance of a possible genotype-feeding-regime interaction are discussed.

Hepatic metallothionein level and mixed function oxidase activity in fingerling rainbow trout (Oncorhynchus mykiss) after acute exposure to pulp and paper mill effluents

Hepatic metallothionein (MT) levels and mixed function oxidase (MFO) activity (7-ethoxyresorufin-o-deethylase or EROD) were measured in fingerling rainbow trout (Oncorhynchus mykiss) exposed to sublethal concentrations of 12 pulp and paper effluents, after completion of 96 h static acute lethality assays. Barring one primary-treated effluent where MFO levels were significantly depressed and two secondary-treated effluents where no significant MFO induction were observed, all other effluents triggered significant induction of MT and EROD, regardless of mill process/treatment or of effluent lethality and chemical characteristics. MT and EROD inductions were significant, however, at higher concentrations for secondary-treated effluents than for primary-treated ones. Lethal (96 h LC50s) to sublethal (MT and EROD lowest observable effect concentrations) ratios were variable and indicated that significant biochemical effects were present at effluent concentrations that were roughly 4–33 (MT) and 3–59 (EROD) times lower than the LC30. Enzyme induction ranged from 1.3 to 2.5-fold for MT and from 1.3 to 9.4-fold for EROD compared to controls. Limited chemical data available suggest that there were indeed classes of compounds present capable of inducing MT or EROD. Observed patterns of MT/MFO responses also suggest that contaminant interactions may have interfered with induction for some of the effluents studied. Refinements of this combined (sub)lethal bioassay procedure are envisaged to determine whether it can provide an efficient means of detecting hazardous chemicals in industrial wastewaters.

An Empirical Model of Gastric Evacuation Rates for Fish and an Analysis of Digestion in Piscivorous Brown Trout

The gastric evacuation rates of brown trout Salmo trutta (0.9–1.6 kg) feeding on fingerling rainbow trout Oncorhynchus mykiss (3.5–7.6 g) were measured in the laboratory at five temperatures (4.5, 9.0, 14.0, 19.0, and 22.5°C). Instantaneous gut evacuation rates (Re) increased exponentially with temperature (T): Re = 0.053·e0.073·T, r2 = 0.98; they varyied from 7%·h–1 at 4.5°C to 29%·h–1 at 22.5°C. Linear regressions described the relationship between time and qualitative measures of fish digestion, thus allowing investigators to determine how long an ingested fish would be identifiable at different temperatures. An analysis of published evacuation rates (N = 121) of 22 fish species indicated that both temperature and prey size (PS, g wet weight) significantly affected digestion rate (Re): Re = 0.049·e0.072·T– 0.060 loge(PS)R2 = 0.52. Predator size did not significantly affect rates of evacuation.