• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.3
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• pp.423-431
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• 2020

This study was conducted to investigate in vivo and in vitro digestibility in juvenile Atlantic Bluefin tuna Thunnus thynnus. In vivo digestibility was compared between four experimental diets to determine the optimum dietary inclusion level of an enzyme-treated sardine fish meal (EFM) and sardine fish meal (FM). The experimental diets were as follows; EFM75 (75% EFM), EFM60 (60% EFM and 15% FM), FM75 (75% FM) and SL (frozen sand lance) as a raw fish feed. Feces of Bluefin tuna (90.3 g) were collected both by siphoning from a 700 L cage and by dissection in 69 ton concrete rearing tanks. For the siphoning method, protein digestibility was higher in the tuna fed SL diet than that of other groups. The lowest protein digestibility was observed in FM75. For the dissection method, protein digestibility was higher in tuna fed EFM75 diet than that of other groups. The lowest protein digestibility was observed in the EFM60 group. In vitro digestibility was compared in six protein sources to find an alternative source of EFM for the tuna feed. The highest in vitro digestibility was observed in EFM (92%) followed by low temperature FM (72%), meat meal (65%), feather meal (60%), sardine fish meal (57%) and poultry by-product meal (55%).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.181-190
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• 2020

This study was conducted to estimate the optimum dietary DHA oil level and replacement level of enzyme treated fish meal (EFM) with sardine fish meal for juvenile Atlantic bluefin tuna Thunnus thynnus. Four diets were used: 1) EFM75 in which 75% EFM and 4% DHA oil were applied, 2) EFM60, with 60% EFM and 15% sardine fish meal, 3) DHA2 with 2% of DHA oil, and 4) SL as a raw fish feed. In a feeding trial, juvenile bluefin tuna (body weight 30.1 g) were randomly stocked into four experimental tanks (69 tones) and fed the experimental diets for 13 days. Fish weight gain was higher in the EFM75 and SL groups than in the DHA2 and EFM60 groups. The feed conversion ratio was lower in the EFM75 and DHA2 groups than in the EFM60 and SL groups. Survival was higher in fish fed the formulated diet groups (EFM75, EFM60 and DHA2) than in fish fed SL. This study clearly indicates that up to 10% dietary sardine fish meal can be used in juvenile T. thynnus diets, with an optimum dietary DHA oil level of approximately 3%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.5
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• pp.741-748
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• 2023

This study evaluated the supplemental effects of linseed oil (LO) as a substitute for docosahexaenoic acid oil (DHAO) in the diet of juvenile Atlantic bluefin tuna. A control diet (DHA) was formulated to contain 65% enzyme-treated fish meal and 3% of DHAO. A LO diet was formulated to contain 1% LO replacing 1% DHAO in DHA diet. In a feeding trial, 300 juvenile bluefin tuna (initial body weight 1.15 g) were randomly divided into two concrete tanks (70 ton capacity) and fed one of the experimental diets for 13 days. Weight gain was higher in the LO group (519%) than in the control (443%) while survival and protein digestibility were similar between groups. The biological assessment of the tuna digestive organs did not differ between the DHA and LO groups. The fatty acid composition of the carcass showed that α-linolenic acid was only observed in the LO group, and there was no difference in the composition of eicosapentaenoic acid and docosapentaenoic acid between the groups. These results indicate that LO could be a dietary good oil source for Atlantic bluefin tuna without apparent negative effects.

• Journal of Nutrition and Health
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• v.29 no.2
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• pp.232-241
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• 1996

This study was designed to compare the effect of different dietary fats on plasma lipids, the degree of lipid peroxidation and the activity of antioxidant enzymes in RBC and liver rats treated with or wighout 1, 2-dimethylhydrazing (DMH). Male Sprague Dawley rats, at 7 weeks-old, were divided into control and DMH-treated grous, and each group was again subdivided into four were perilla oil (PO), blend fat (BF) containing ten different kinds of dietary oil, beef tallow (BT), corn oil (CO). At the same time, each rat was injected intramusculary with saline(for control) or DMH twice a week for 6 weeks to give total dose of 180 mg/kg body weight. Compared with BT feeding, BF reduced plasma total choesterol level and PO and Co reduced plasma TG levels (p<0.05). DMH injection decreased plasma cholesterol in all dietary groups. However, PO decreased tocopherol levels and increased TBARS levels in RBC compared to BT. The degree of hemolysis in PO group was higher than that of BT group (p<0.05 only in control group. Fatty acid composition of hepatic microsome was reflected by dietary fatty acid profile. The peroxidizability index and TBARS level in hepatic micorsome were significantly increased but tocopherol level was lowered in PO group compared to BT group. Activites of superoxide dismutase and glutathione peroxidase in RBC and hepatic cytosol were not influenced y dietary fats and DMH treatment(p<0.05). Overall, perilla oil rich in $\omega$3 $\alpha$-linolenic acid could be a very important dietary source in reducing plasma lipids and blend fat was also good dietary oil mixture in reducing plasma cholesterol. However, the degree of lipid peroxidation was greater in tissue by perilla oil feeding and it is very difficult to use only perilla oil as oil source for meal preparation, so that it could be suggested to use more perilla oil and fish to give an equal effect of blend fat in order to reduce the risk factors against cardiovascular disease.

• Journal of Aquaculture
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• v.21 no.4
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• pp.272-277
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• 2008

We investigated the growth and survival in seedling production, and growth performance was compared with the different rearing tanks and protein source of formulated feed for juvenile Pacific bluefin tuna Thunnus orientalis (PBT). The survival rate at the end of nursery culture at 30 days after hatching was $0.69{\pm}0.40%$, and total length and mean body weight were $49.83{\pm}2.52\;mm$ and $1.03{\pm}0.09\;g$, respectively. Growth performance has no significant difference in fish reared by different tanks forms for 10 days. In order to develop an artificial diet, we evaluated the dietary utility of enzyme treated fish meal (Bio-CP, BIO) for juvenile PBT. Only diet BIO sustained similar growth and higher feed efficiency, and final carcass lipid content as compared to those of Sand lance (SL) These results revealed that BIO-CP a suitable dietary protein source, could sustain growth of PBT.