1998 Fiscal Year Final Research Report Summary
Development of Dry Pellets for Broodstock Yellowtail
| Project/Area Number |
08406015
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fisheries chemistry
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| Research Institution | Tokyo University of Fisheries |
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Principal Investigator |
WATANABE Takeshi Tokyo University of Fisheries, Professor, 水産学部, 教授 (60017051)
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| Co-Investigator(Kenkyū-buntansha) |
MAITA Masashi Tokyo University of Fisheries, Aquatic Biosciences, Assistant Professor, 水産学部, 助教授 (60238839)
SATOH Shuichi Tokyo University of Fisheries, Aquatic Biosciences, Associate Professor, 水産学部, 助教授 (80154053)
TAKEUCHI Toshio Tokyo University of Fisheries, Aquatic Biosciences, Professor, 水産学部, 教授 (70092591)
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| Project Period (FY) |
1996 – 1998
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| Keywords | Broodstock / Yellowtail / Egg quality / Astaxanthin / Zeaxanthin / Lutein |
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| Research Abstract |
This research was conducted to gather some basic information necessary for the development of superior dry pellets for yellowtail broodstock, inturn enabling them to enhance their egg quality. A new type of extruded dry pellet (SDP) was found to be effective for culturing the broodstock from the juvenile stage, under captivity.
Dietary carotenoid is the focus of this study. Astaxanthin (Astx) was investigated first because it has been proven to enhance quality of red seabream eggs. Brood fish fed the SDP supplemented with Astx (20 and 30 ppm) produced a greater number of normal eggs comprising high percentages of buoyant and fertilized eggs, the optimum being at 30 ppm Astx. Addition of 40 ppm Astx in the SDP seemed to be an over-dose because the quality of eggs deteriorated. Thus, the supplementation of Astx in SDP was found to be effective for broodstock yellowtail. Dietary Astx was also found to be incorporated into eggs as zeaxanthin (Zeax) and lutein, and both carotenoids were immediately bioconverted to tunaxanthin after hatching. These results suggested that Zeax may be more effective than Astx in improving egg quality, judging from their order of appearance in the metabolic pathway.
In the follow-up study, however, supplementation of 6.6% spirnlina in SDP to obtain around 30 ppm Zeax, resulted in excess amounts of carotenoids (200 ppm in total), disturbing the gonadal maturation of the broodstock. Thus, spirulina containing various kinds of carotenoids did not serve as an ideal Zeax source, and at this point, Astx alone remains to be the carotenoid of choice to enhance quality of yellowtail eggs.
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Research Products
(10 results)
