• Animal cells and systems
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• v.4 no.3
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• pp.287-292
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• 2000

The present work examined the role of gonadotropin-releasing hormone (GnRH) and dopaminergic drugs on the secretion of maturational gonadotropin (GTH II) in relation to testosterone m treatment. This study provides evidence that the plasma GTH II levels are increased by T treatment in precocious males, but not in the immature animal. In addition, GnRH analogue (GnRHa) alone significantly increased the plasma GTH II secretion in immature rainbow trout treated with T, as well as in T-treated and T-untreated precocious males. However, injection with either dopamine (DA) or domperidone (DOM; DA D2 receptor antagonist) alone did not alter the basal plasma GTH 11 secretion in all experimental groups. The secretion of GTH II in the T-treated precocious males was remarkably influenced by GnRHa or combination of dopaminergic drugs. Notably, the effects of dopaminergic drugs on GnRHa-induced GTH II secretion w8s prolonged by T in precocious males. In T-treated immature animals, GnRHa-induced GTH II secretion was Increased only by a dose DOM (10$\mu$g/g body n) but not by higher dose DOM (100$\mu$/g body wt). In the T-untreated immature rainbow trout, however, plasma GTH 11 secretion was not influenced by the same treatments. Therefore, these results indicate that DA may be acting indirectly by blocking the effect of GnRH on GTH II secretion in vivo. T may act to modulate the relative contribution by the stimulatory (GnRH) and inhibitory (DA) neuroendocrine factors, which would ultimately determine the pattern of GTH II secretion.

• KSBB Journal
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• v.15 no.6
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• pp.658-663
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• 2000

This study is aimed at evaluating the pigmentation of rainbow trout with carotenoid extracts from halophilic bacteria during 8 weeks feeding. Proximate composition of the sample were analyzed. Moisture content was 77% and 73% after 4 and 8 weeks feeding, respectively. Crude protein and lipid content was slowly increased after 8 weeks feeding. But minerals content were not affected with the feeding period and constituents. Muscle carotenoids content of rainbow trout was 0.0223 mg/100g tissue in control group after 4 weeks, and 0.1702 mg/100g tissue in carophyll pink group after 8 weeks. The carotenoids pigmentation content of halophilic bacteria extracts fed group was 0.1256, 0.1382 mg/100g tissue after 8 weeks. It means that the carotenoids of bacteria extracts are a good material for fish pigmentation. The main components of rainbow trout muscle and integuments with these diets were canthaxathin,, zeaxanthin, and ${\beta}$-carotene.

• Journal of Aquaculture
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• v.18 no.2
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• pp.69-75
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• 2005

One 30-day feeding trial was conducted to examine the effects of dietary salt on seawater adaptability of rainbow trout (Onchorhynchus mykiss) fed three experimental diets containing 0% (control), 4% and 8% salt. The experimetal period included 30 days of feeding trial in freshwater, 3 days of the step by step seawater acclimation with-out feeding diets, and 21 more days of seawater adaptation period (not with all experimental fish) with feeding the basal diet. Growth rates from triplicate groups were determined fur 30 days of feeding trial. Blood samples were taken at the begining and at the end of feeding trial, and 3 times (on 1st, 4th and 8th day) of the seawater adaptation period. Daily survival rates of duplicate groups from three experimetal treatments were recorded for 21 days of the seawater adaptation period. Total average initial and final fish weight were $149.5{\pm}7.6\;and\;187.1{\pm}7.6g$. Feed efficiency of fish fed diets containing 4% and 8% salt were significantly better than those of fish fed the control diet. Average cumulative survival rates were 72, 80 and 88% from the control, 4% and 8% salt diets, respectively. Pulse rate per minutes decreased with dietary salt level. Serum $Na^+\;and\;Cl^-$ concentrations of fish fed 4% and 8% salt diets were significantly higher than those of fish fed the control diet (P<0.05), however, the concentrations were stabilized after 8 days of seawater adaptation. Serum cortisol, glucose, cholesterol and tryglyceride concentrations, and the osmorality of fish decreased with dietary salt level, these values were significantly lower than those of fish fed the control diet. These results indicated that the dietary supplementation of salt could have advantages for seawater adaptability of rainbow trout.

• Fisheries and Aquatic Sciences
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• v.21 no.11
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• pp.32.1-32.7
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• 2018

Trout production is a growing activity in recent years but requires new alternative sources of feed to be sustainable over time. The objective of this research was to determine the apparent digestibility coefficient (ADC) of dry matter (DM), organic matter (OM), crude protein (CP) and digestible energy (DE) of $ka{\tilde{n}}iwa$ (Chenopodium pallidicaule Aellen), kiwicha (Amaranthus caudatus L), quinoa (Chenopodium quinoa Willd), beans (Phaseolus vulgaris L.), sacha inchi, (Plukenetia volubilis L) and jumbo squid (Dosidicus gigas) meal in juvenile rainbow trout. The experimental diets were composed of a 70% basal diet and 30% of any raw materials. The ADC was determined by the indirect method using insoluble ash as a non-digestible marker. Jumbo squid, sacha inchi and quinoa showed the highest values of ADC (%) of DM (84.5, 73.5 and 69.7), OM (89.1, 78.4 and 72.9), CP (93.2, 98.0 and 90.3), and DE (4.57, 4.15 and 2.95 Mcal/kg DM), respectively. The ADC values for $ka{\tilde{n}}iwa$, kiwicha and bean were significantly lower. In conclusion, quinoa meal and jumbo squid meal have an acceptable digestibility but sacha inchi meal is a potential alternative for rainbow trout feeding in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.1
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• pp.79-88
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• 2023

A 12-week feeding trial was conducted to evaluate the effect of different stocking densities on the growth, body composition, stress, antioxidant status, and immune responses of juvenile rainbow trout Oncorhynchus mykiss. Juvenile rainbow trout (32.2±0.5 g) were randomly placed in eight experimental tanks, each containing 2,000 L of water, at stocking densities of 150, 300, 600, and 1,200 individual/m³. The trout were assigned to four treatments (2.4, 4.8, 9.7, and 19.4 kg/m³) in duplicates. Following after the feeding trial, the fish cultured in the less dense group showed significantly higher growth and survival (P<0.05). In terms of proximate composition, the whole body crude protein and lipid contents were lower in the denser group (19.4 kg/m³). Regarding the antioxidant and immune responses, the fish reared in the relatively denser group exhibited lower lysozyme, immunoglobulin M, and superoxide dismutase levels. The stress indicators, glucose and cortisol, were significantly lower in the less dense group (2.4 kg/m³), while the denser group (19.4 km/m³) exhibited higher AST and ALP levels(P<0.05). The results showed that denser stocking has a crowding stress effect and negatively impacts growth and immune responses.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.505-511
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• 2023

This study investigated the effect of transglutaminase (TGase) and polysaccharide kappa carrageenan on the texture, chemical, and microbiological qualities of refrigerated unmarketable rainbow trout Oncorhynchus mykiss. Gel strength increased substantially in TGase-treated samples, and was adding kappa carrageenan resulted in no significant difference. SDS-PAGE results confirmed that the myosin heavy chain band with a molecular weight of 205-250 kDa was weakened in trout meat treated with 1% TGase, which led to cross-linking reactions between proteins. The volatile basic nitrogen (VBN) increased in all samples during storage at 4℃ for 10 days; however, the samples treated with 0.5% and 1% kappa carrageenan had the lowest VBN. The viable cell count increased in all samples treated with TGase and kappa carrageenan; however, an increase in TGase enzyme and kappa carrageenan concentration successfully hindered total bacteria growth. Thus, adding 1% TGase and 1% kappa carrageenan to refrigerated unmarketable rainbow trout formulations can optimize quality characteristics.

• Journal of fish pathology
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• v.36 no.2
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• pp.415-422
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• 2023

In veterinary medicine for mammals, studies are being conducted to confirm the effects of antioxidants using pathological toxicity model studies, and are also used to confirm the effect of mitigating liver or kidney toxicity of specific substances. It was considered necessary to study such a toxicity model for domestic farmed fish, so thioacetamide (TAA), a toxic substance that causes tissue damage by mitochondrial dysfunction, was injected into rainbow trout (Oncorhynchus mykiss), a major farmed freshwater fish species in Korea. The experiment was conducted with 40 rainbow trout (Oncorhynchus mykiss) weighting 53 ± 0.6 g divided into two groups. Thioacetamide(TAA) 300mg/kg of body weight was intraperitoneally injected into rainbow trout and samples were taken 1, 3, 5, 7 days after peritoneal injection. As a result, in serum biochemical analysis, AST levels related to liver function decreased 3 and 5 days after intraperitoneal injection and increased after 7 days, and ALT levels also increased after 7 days. In addition, creatinine related to renal malfunction increased 3 and 5 days after TAA injection. In histopathological analysis, pericholangitis and local lymphocyte infiltration were observed in the liver from 1 day after intraperitoneal injection of TAA, and hepatic parenchymal cell necrosis was also observed from 3 days after intraperitoneal injection. Hyaline droplet in renal tubular epithelial cell was observed from 1 day after TAA injection, and acute tubular damage such as tubular epithelial cell necrosis appeared from 3 days after TAA injection. Accordingly, it is thought that it will be able to contribute to studies that require a toxicity model.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.180-185
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• 2001

Al and Cd-induced inhibition of vitellogenin (VTG) production was examined at the estrogen receptor (ER) level in rainbow trout Oncorhynchus mykiss hepatocytes. The binding of $[^3H]$ $estradiol-17\beta\;(E_2)$ to hepatocytes reached a plateau 3 days after addition of $E_2\;(2\times\;10^{-6} M)$to the medium. The binding activity was linearly reduced with the increased concentrations $(-10^{-5}\;M)$ of 4-hydroxy-tamoxifen (4-OHT) and specific binding linearly increased with the increased doses of $[^3H]\;E_2$, indicating that the radioligand bound to ER. Al $(-10^{-4}\;M)$and Cd $(10^{-6}\;M)$ as well as 4-OHT $(10^{-6}\;M)$ significantly reduced the $[^3H]\;E_2$-binding activity by $30­40\%$, while they completely inhibited VTG production. Al and Cd had no effect on $E_2-human$ $ER\alpha$ binding activity at any concentrations used $(-10^5\;nM\;each)$. These results suggested that Al and Cd inhibited VTG production in part by interfereing with the ER level. Inhibitory effects of these metals on the $E_z-dependent$ upregulation of ER activity are also discussed.

• Fisheries and Aquatic Sciences
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• v.4 no.4
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• pp.186-191
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• 2001

Vitellogenin (VTG) and VTG mRNA induction by $estradiol-17\beta\;(E_2)$ were examined in the primary cultures of hepatocyte in the rainbow trout. Hepatocytes were precultured for 2 days, then $E_2$ was added and cultured for another 5 days. Media and hepatocytes were then analyzed by electrophoresis and Northern blotting for VTG and VTG mRNA, respectively. The hepatocytes were formed a few aggregates within 5 days without further spreading to a monolayer. Cell viability and high DNA content were maintained during the incubation. The hepatocyte culture with E2 induced a weak VTG band at a molecular weight of 175kDa on Day 2 after $E_2$ addition. The relative amount of VTG was expressed in percentage of total protein concentrations. VTG was gradually increased as $1.9\%$ on Day 2, $6.3\%$ on Day 4 and $7.3\%$ on Day 5. VTG mRNA band was detected at about 6.6 kb in the culture with $E_2$ at day 1 of culture. The level of VTG mRNA expression linearly increased with time until Day 5 (r=0.97).

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.5
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• pp.700-705
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• 2014

A 12-week feeding trial was conducted with 87 g rainbow trout to evaluate the effects on growth performances, feed efficiency and nutrient digestibility of adding ${\beta}$-mannanase and ${\alpha}$-galactosidase enzymes, solely or in combination. Seven diets were prepared by adding ${\beta}$-mannanase, ${\alpha}$-galactosidase and mixed enzyme at two different levels (1 g/kg and 2 g/kg) to control diet (without enzyme) including soybean meal. Mixed enzymes (1 g/kg, 2 g/kg) were prepared by adding ${\beta}$-mannanase and ${\alpha}$-galactosidase at the same doses (0.5+0.5 g/kg and 1+1 g/kg). At the end of the experiment, addition of ${\beta}$-mannanase, ${\alpha}$-galactosidase and mixed enzyme to diet containing 44% soybean meal had no significant effects on growth performance and gain:feed (p>0.05). In addition, adding ${\beta}$-mannanase, ${\alpha}$-galactosidase and mixed enzyme in different rations to trout diets had no affect on nutrient digestibility and body composition (p>0.05).