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Manual on the Production and Use of Live Food for Aquaculture - Phần 6

Tham khảo tài liệu 'manual on the production and use of live food for aquaculture - phần 6', nông - lâm - ngư, ngư nghiệp phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 21 add correction to measured density - - .001 .001 .001 - 22 .001 .001 .001 .001 .001 .001 23 .001 .001 .001 .002 .002 .001 24 .001 .002 .002 .002 .002 .002 25 .002 .002 .003 .003 .003 .002 26 .002 .002 .003 .003 .003 .003 27 .003 .003 .004 .004 .004 .004 28 .003 .003 .004 .005 .005 .004 29 .004 .004 .005 .005 .005 .005 30 .004 .004 .005 .006 .006 .006 31 .004 .005 .006 .006 .006 .006 32 .005 .006 .006 .007 .007 .007 33 .005 .007 .007 .007 .007 .007 34 .006 .007 .007 .008 .008 .008 35 .006 .007 .008 .008 .008 .008 nnn BD 4.3. Use of nauplii and meta-nauplii 4.3.1. Harvesting and distribution 4.3.2. Cold storage 4.3.3. Nutritional quality 4.3.4. Enrichment with nutrients 4.3.5. Enrichment for disease control 4.3.6. Applications of Artemia for feeding different species 4.3.7. Literature of interest 4.3.8. Worksheets Greet Merchie Laboratory of Aquaculture Artemia Reference Center University of Gent Belgium 4.3.1. Harvesting and distribution After hatching and prior to feeding the nauplii to fish crustacean larvae they should be separated from the hatching wastes empty cyst shells unhatched cysts debris microorganisms and hatching metabolites . Five to ten minutes after switching off the aeration cyst shells will float and can be removed from the surface while nauplii and unhatched cysts will concentrate at the bottom Fig. 4.3.1. . Figure 4.3.1. Hatching container at harvest. Since nauplii are positively phototactic their concentration can be improved by shading the upper part of the hatching tank use of cover and focusing a light source on the transparent conical part of the bottom. Nauplii should not be allowed to settle for too long i.e. maximum 5 to 10 min. in the point of the conical container to prevent dying off due to oxygen depletion. Firstly unhatched cysts and other debris that have accumulated underneath the nauplii are siphoned or drained off when necessary i.e. when using cysts of a lower hatching quality . Then the nauplii are collected on a filter .