• Fisheries and Aquatic Sciences
• /
• v.12 no.4
• /
• pp.258-264
• /
• 2009

A commercial diet supplemented with carotenoids and conjugated linoleic acid was fed to rainbow trout (Oncorhynchus mykiss) for 8 weeks. To investigate the anti-oxidative properties of these compounds, lipids from the muscle and viscera of the fish were subjected to different assays. At $10\;{\mu}g/mL$, L-ascorbic acid exhibited 95% 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, while the tissue lipids showed little radical scavenging activity. At 50 and $100\;{\mu}g/mL$, the lipids of the muscles and viscera showed 11.7-22.6% and 11.3-24.9% DPPH radical-scavenging activity, respectively. A lipid peroxidation inhibitory assay using the ferric thiocyanate method was also performed in comparison with $\alpha$-tocopherol at a concentration of 6.0 mg/mL. Our results indicate that the anti-oxidative property of the lipids in fish muscle, which was 85.2% compared to 85.3% for the visceral lipids, was stronger than that of $\alpha$-tocopherol (74.3%) following 3 days of storage at $40^{\circ}C$.

• Fisheries and Aquatic Sciences
• /
• v.23 no.5
• /
• pp.12.1-12.8
• /
• 2020

Background: An 8-week feeding trial was designed to evaluate the potential of yellow mealworm (MW; Tenebrio molitor) as a locally available nutrient-rich feedstuff for rainbow trout fry (Oncorhynchus mykiss). Methods: Triplicate groups of fish (mean ± SE; 1.11 ± 0.01 g) were assigned to each of the five isonitrogenous and isocaloric practical diets containing graded level of a full fat MW (0, 7, 14, 21, and 28%) at the expense of fish meal (designated as MW0, MW7, MW14, MW21, and MW28, respectively). Results: Fish growth performance in terms of weight gain and specific growth rate significantly increased with increasing dietary MW level up to 14% and then declined when dietary MW levels further increased to 28%. Significantly higher protein efficiency ratio and lower feed conversion ratio were found in fish fed with diets containing MW compared to fish fed the control MW0. Myeloperoxidase activity was significantly higher in fish fed MW7 diet compared to fish fed the MW0 diet. Fish fed the MW14 and MW28 diets had significantly higher lysozyme activities than those fed the MW0 diet. Conclusions: Overall, the efficacy of MW as promising alternative to fish meal in practical diets for rainbow trout fry has been proved not only in relation to growth rates and feed utilization, but also from the viewpoint of immunopotentiation effects.

• Fisheries and Aquatic Sciences
• /
• v.14 no.4
• /
• pp.379-388
• /
• 2011

The mechanism by which gonadotropin-releasing hormone (GnRH) and dopamine (DA) control gonadotropin (GTH) release was studied in male and female rainbow trout using cultured pituitary cells obtained at different reproductive stages. The mechanisms of follicle-stimulating hormone (FSH) release by GnRH and DA could not be determined yet. However, basal and salmon-type GnRH (sGnRH)- or chicken-II-type GnRH (cGnRH-II)- induced luteinizing hormone (LH) release increased with gonadal maturation in both sexes. LH release activity was higher after sGnRH stimulation than cGnRH-II stimulation at maturing stages in both sexes. The GnRH antagonist ([Ac-3, 4-dehydro-$Pro^1$, D-p-F-$Phe^2$, D-$Trp^{3,6}$] GnRH) suppressed LH release by sGnRH stimulation in a dose-dependent manner, although the effect was weak in maturing fish. The role of DA as a GTH-release inhibitory factor differs during the reproductive cycle: the inhibition of sGnRH-stimulated LH release by DA was stronger in immature fish than in maturing, ovulating, or spermiated fish. DA did not completely inhibit sGnRH-stimulated LH release, and DA alone did not alter basal LH release. Relatively high doses ($10^{-6}$ or $10^{-5}M$) of domperidone (DOM, a DA D2 antagonist) increased LH release, which did not change with reproductive stage in either sex. The potency of DOM to enhance sGnRH-stimulated LH release was higher in maturing and ovulated fish than in immature fish. These data suggest that LH release from the pituitary gland is controlled by dual neuroendocrine mechanisms by GnRH and DA in rainbow trout, as has been reported in other teleosts. The mechanism of control of FSH release, however, remains unknown.

• Preventive Nutrition and Food Science
• /
• v.21 no.3
• /
• pp.281-288
• /
• 2016

This study was designed to investigate the effects of dietary astaxanthin levels on growth performance, feed utilization, muscle pigmentation, and antioxidant capacity in juvenile rainbow trout. Four experimental diets were formulated to contain 0, 50, 75, and 100 mg/kg astaxanthin (designed as AX0, AX50, AX75, and AX100). Each diet was fed to triplicate groups of fish (18.5 g/fish) for 10 weeks. Growth performance and muscle composition of fish were not affected by dietary astaxanthin levels. Total carotenoid concentration in the muscle of fish fed the AX50 diet was higher than that of fish fed the AX0 diet, but no significant differences were observed between these fish and those fed the AX75 and AX100 diets. Muscle astaxanthin content increased with increased astaxanthin in the diet. Deposition of astaxanthin in the flesh resulted in a decrease in lightness and an increase in redness and yellowness. The fillets from trout fed the AX75 diet had significantly lower lightness than trout fed the AX50 and AX100 diets. Fish fed the AX50 and AX75 diets showed significantly lower catalase activity than those fed the control diet. Total antioxidant status increased significantly in all astaxanthin supplemented groups when compared to the control group. Superoxide dismutase activity was significantly decreased in fish fed the AX50 diet compared to fish fed the AX0 diet. These findings suggest that while fillet pigmentation increased with increasing dietary astaxanthin concentration, indices of fish antioxidant capacity may not be affected in a dose dependent manner.

• Animal cells and systems
• /
• v.13 no.4
• /
• pp.429-437
• /
• 2009

The control mechanism of gonadotropin-releasing hormone (GnRH) on gonadotropin (GTH) release was studied using cultured pituitary cell or cultured whole pituitary obtained from Testosterone (T) treated and control immature rainbow trout. The release of FSH was not changed by salmon type GnRH (sGnRH), chiken-II type (cGnRH-II), GnRH analogue ([des-$Gly^{10}D-Ala^6$] GnRH ethylamide) and GnRH antagonist ([Ac-3, 4-dehydro-$Pro^1$, D-p-F-$Phe^2$, D-$Trp^{3,6}$] GnRH) in cultured pituitary cells of T-treated and control fish. Indeed, FSH release was not also altered by sGnRH in cultured whole pituitary. All tested drugs had no effect on the release of LH in both culture systems of control fish. The levels of LH, in contrast, such as the pituitary content, basal release and responsiveness to GnRH were increased by T administration in both culture systems. In addition, the release of LH in response to sGnRH or cGnRH-II induced in a dose-dependent manner from cultured pituitary cells of T-treated fish, but which is not significantly different between in both GnRH at the concentration examined. Indeed, LH release was also increased by sGnRH in cultured whole pituitary of T-treated fish. GnRH antagonist suppressed the release of LH by sGnRH ($10^{-8}\;M$) and GnRH analogue ($10^{-8}\;M$) stimulation in a dose-dependent manner from cultured pituitary cells of T-treated fish, and which were totally inhibited by $10^{-7}\;M$ GnRH antagonist. These results indicate that the sensitivity of pituitary cells to GnRH is elevated probably through the T treatment, and that GnRH is involved in the regulation of LH release. GnRH-stimulated LH release is inhibited by GnRH antagonist in a dose-dependent manner. The effects of gonadal steroids on FSH levels are less clear.

• Journal of Aquaculture
• /
• v.10 no.1
• /
• pp.39-47
• /
• 1997

Induction of hybrid and allotriploid between female rainbow trout, oncorhynchus mykiss and male cherry salmon, O. masou were performed. Triploid rate in allotriploid was 92% and the survival rates of allotriploid exceeded that of their hybrid counterparts. Karyological studies revealed that the hybrid had exactly the same intermediate diploid karyotypers as that of two parental species, while allotriploid had two sets of the maternal haploid complement and one set of the paternal haploid complement. Hybrid revealed an intermediate size in celluar and nuclear size of erythrocyte, while allotriploid revealed larger cellular and nuclear size of erythrocytes than hybrid. The number of nucleolar organizer regions of hybrid were 1 or 2, while those of allotriploids were 1, 2 or 3. These results proved that allotriploidization can lead to increase cytogenetical characters compared to counterpart hybridization.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.55 no.5
• /
• pp.688-696
• /
• 2022

Obesity could cause immune-physiological disorders in fish. Yet, little is known about the impact of obesity on stress and histological responses. This study aimed to determine histological and physiological changes in and vulnerability of overfeeding-induced obese rainbow trout Oncorhynchus mykiss exposed to stress condition. Control, intermediate and overfed groups were fed at 1.5, 2.5 and 3.09% of their body weight per day, respectively, for eight weeks. Weight gain, body mass index, hepatosomatic index and serological parameters, and histology of liver were measured in five fish from each group at week 0, 2, 4, and 8. At week 8, 20 fish from each group were exposed to heat stress by increasing water temperature at a rate of 3℃ per day from 15 to 25℃ and maintaining the final temperature for 10 days. Overall, overfed fish showed significantly higher weight gain, body mass index, and serological parameters than those of fish in the other groups. Fish in the overfed and intermediate groups displayed multifocal infiltration of inflammatory cells in hepatic parenchyma. Mortality rate and serological parameters of fish in the overfed group exposed to heat stress were significantly higher than those of fish in the other groups, indicating increased vulnerability to environmental stress.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.56 no.5
• /
• pp.585-595
• /
• 2023

This study was conducted to optimize the rice paper roll processing conditions with frozen rainbow trout Oncorhynchus mykiss meat (RPR-FRT) treated with polysaccharide and TGase using a response surface methodology and to examine their quality characteristics. The RSM results for the RPR-FRT showed that the optimum condition for the garlic-pepper mixture was 21.2 g and that for starch was 22.6 g based on 150 g of RPR-FRT. The RPR-FRT contained 58.47 g/100 g of moisture, 8.57 g/100 g of crude protein, 3.28 g/100 g of crude lipid, and 1.00 g/100 g of ash. The vitamin E content was 1,010.91 ㎍/100 g. Based on their contents, the samples could be considered good supplements for P, Cr, and Se. The RPR-FRT contained unsaturated fatty acids (75.84%), DHA (10.33%), and EPA (2.56%). Anserine, arginine, glycine, and taurine accounted for 41.93%, 11.27%, 7.13%, and 7.00% of free amino acids in the RPR-FRT, respectively. The sulfur compounds in the RPR-FRT constituted 73.16% of the total flavor compounds. The RPR-FRT prepared using the optimum conditions was superior in masking off-flavor and showed improved nutritional content.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.33 no.1
• /
• pp.55-59
• /
• 2000

A specific and sensitive sandwich enzyme-immunoassay (EIA) using Avidin-Biotin complex was developed for the measurement of GTH II levels in pituitary content and pituitary cell culture medium of the rainbow trout-(Oncorhpchus mykiss). Biotin-salmon GTH II rabbit IgG (sefondary antibody) wai purified by a protein A sepharose affinity chromatography column and that was biotinylated by using Biotin-N-hydroxysuccinimide ofter (BNHS). Non-biotin salmon GTH II rabbit IgG (first antibody) was obtained only through a protein A sepharose affinity chromatography column. The assay was performed by the so-called 'sandwich' method using a microtiter plate, A dose-response curve was obtained between $0.12 to 125 ng/ml$ of salmon GTH II. The displacement curves for pituitary extraction and pituitary cell culture medium of testosterone-treated rainbow trout were Parallel to the standard curie. The intra-assay and inter-assay coefficients of variation (CV) were $8.2{\%} (N=5) and 12.5{\%} (N=6)$, respectively, This assay system was used to measure the amount of GTH II that accumulated in the culture medium of dispersed pituitary cells in testosterone-treated immature rainbow trout, The accumulation was increased with the amount or salmon gonadotropin-releasing hormone. GTH II values determined by the present method were well correlated with those determined by radioimmunoassay. As a result, this assay system was found to be suitable for the measurement of GTH II for pituitary extraction and pituitary culture medium in many salmonid fishes.

• Journal of Aquaculture
• /
• v.9 no.4
• /
• pp.395-407
• /
• 1996

A feeding experiment for 160 days was conducted to evaluate effects of dietary soybean meal (SBM) on the apparent digestibility, ammonia excretion and body composition of rainbow trout (Oncorhynchus mykiss). Seven diets containing $0\~70\%$ SBM were formulated based on iso-nitrogenous and iso-caloric basis of $44\%$ crude protein and approximately 4,200 Kcal/kg of gross energy. To evaluate the nutritional utilization of the SBM diets at the end of 60 and 120-day rearing with test diets, digestion rates of protein and lipid of SBM diets were measured. Fish fed the diets containing above $46\%$ SBM showed higher apparent digestibility for protein, but lower for lipid than did fish fed the control diet in both trials. Protein and fat contents in the carcass were similar for all experimental fish, except for fish fed $58\%$ and $70\%$ SBM which showed lower fat content than the others, but composition of fatty acid and amino acids were not affected by dietary SBM levels. Gill and urinary post-prandial ammonia ($NH_3-N$) excretions were measured at 12 and 24 hours after single feeding of the experimental diets. Excretions of $NH_3-N$ measured after 24 hours were almost 1 times higher than those measured after 12 hours. Total excretion fer the 24 hours by fish fed $70\%$ SBM was $15\%$ higher than that of fish fed the control diet. Results of present study may suggest that the rainbow trout which were fed above $34%\;or\;46\%$ of SBM diet showed a decrease gradually in lipid bioavailability compared to the control group.