碩士 / 國立海洋大學 / 水產養殖學系 / 87 / Production of live food organisms is the key to the success of larval rearing. Culture duration and media and nutrition of the food fed to the live food organisms all can affect the quality of the live food organisms, which in turn affects the health and survival of the larva. Rotifer is an important live food organism for marine fish larva. However, HUFA (Highly Unsaturated Fatty Acid) content of rotifer is usually not sufficient to satisfy the nutritional requirement of marine fish larva. This can usually be compensated by enrichment during the cultivation of rotifer.
The purposes of this study were first to evaluate the feasibility of using zeolite powder as the carrier of enrichment substances and as the food for rotifer (Brachionus plicatilis) by examining the suspension condition of the enriched zeolite powder. Then, quality of the rotifer was evaluated by its HUFA profile after it had been fed with the enriched zeolite and/or marine microalgae (Nannochloropsis oculata). Finally, quality of the red sea bream (Pagrus major) larva was evaluated by the survival, growth, ratio of swollen air bladder, stress tolerance, and fatty acids profile of the larva fed with those enriched rotifer.
In the first experiment, 3 kinds of zeolite: Z, zeolite powder without enrichment, as the control; SZ, zeolite powder enriched with emulsified fish oil; and KZ, zeolite powder enriched with krill hydrolysates were dispersed in a 36-cm water column under lightly aerated or stagnant condition. Water was sampled from the surface, middle, and bottom layer at 0 and 4 hr and suspended particles were counted.
At 0 hr, 3 kinds of zeolite distributed homogeneously in all 3 layers. At 4 hr, KZ had more suspended particles than Z and SZ. However, the 4-hr suspension rate (the ratio of suspended particles at 4 hr to 0 hr) was highest for SZ (75%) and lowest for KZ (55%). Aeration increased the suspension rate; 49% and 77% for the stagnant and aerated condition, respectively.
In the second experiment, rotifer was fed in 5 ways: B, no food was provided, as the blank; KZ, zeolite powder enriched with krill hydrolysates was fed; N, only microalgae was fed; NKZ, both N and KZ were fed; and NSZ, both N and SZ (zeolite powder enriched with emulsified fish oil) were fed. At 0, 6, 12, and 24 hr after feeding, population increment, crude lipid content, and fatty acids profiles of rotifer, and water quality were analyzed to evaluate the quality of rotifer.
There were no differences in population increment among these 5 ways of feeding, ranging 89-94%. Crude lipid content in rotifer was highest at 24 hr after feeding and significantly different from the other duration. The rotifer that was fed with KZ, N, NKZ, and NSZ had significantly higher crude lipid content than the rotifer that was not fed in B treatment. The rotifer fed with food containing microalgae, i.e., NSZ, NKZ, and N, their n-3 HUFA were of no difference among each other, but higher than B. DHA (docosahexaenoic acid) in NSZ rotifer was higher than in B rotifer. The results had shown that microalgae contributed to the HUFA in rotifer. Water in all treatments remains unpolluted; ammonia concentration stayed lower than the safe level for rotifer and pH maintained in the range 7.70-7.93.
In the third experiment, rotifer from the second experiment was fed to the red sea bream larva, then survival rate, growth rate, swollen air bladder ratio, stress tolerance, and fatty acids profile of the resulting larva were evaluated.
There was significant increase in DHA and n-3 HUFA profile when the larva fed with enriched rotifer. Larva with higher DHA and n-3 HUFA profile had higher survival rate, growth rate, swollen air bladder ratio, and stress tolerance. Larvae fed with NSZ rotifer had best performance on all those quality parameters for being highest in its n-3 HUFA profile. On the contrary, larva fed with rotifer without enrichment (B rotifer) had the worst performance since such rotifer was not able to provide sufficient nutrition for the larva.
This series of experiments had shown that zeolite powder was suitable to be used as a primary carrier for the enrichment substances. Zeolite enriched with emulsified fish oil was demonstrated as a readily food for rotifer, when together fed with microalgae to the rotifer, HUFA content of the rotifer was greatly enhanced. Fed with such enriched rotifer and small amount of microalgae, which also improved the water quality, to the red sea bream larva, healthy and high vitality larva were obtained.
| Identifer | oai:union.ndltd.org:TW/087NTOU0086020 |
| Date | January 1999 |
| Creators | Huang Ting-Shih, 黃丁士 |
| Contributors | Chien Yew-HU, 陳 瑤 湖 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 129 |
Page generated in 0.0017 seconds