Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 95 === According to Food and Agriculture Organization of United Nation, global ornamental fish market in 2000 worths 900 million USD whole sale, and 3 billion USD retail. In 2003, this industry is valued 14 billion USD including its peripheral industries. Body color and in some cases flesh color of fish is one of the most important quality criteria informing their market value. In this study, the methods for pigmentation assessment in aquatic animals was first reviewed and two experiments were conducted to test a new application for pigment assessment and determine the best area for pigmentation monitoring in atydae shrimp and to find out the effect of dietary carotenoids on pigmentation of juvenile Atydae shrimp.
In the review the common methods for pigment assessment in aquatic animals were commented and compared. The methods can be grouped into: chemical methods, i.e., HPLC, TLC and Spectrophotometry, as they analyse quantitatively and/or qualitatively the carotenoid compound in the tissue; physical methods, i.e., colourimetry, sensory analysis, and digital image acquisition and processing (DIAP), as they evaluate the colour reflected by the pigments in the tissue. The use of chemical methods combined with physical methods can be a more comprehensive approach to reveal the correlation of pigment concentration and colour. A new application of DIAP described has a great potential for precise evaluation of pigmentation in all size aquatic animals both quantitatively and qualitatively without causing stress or damage to the animals.
In the first experiment morphological and chromatic characteristics of chromatophores in carapace, somite and exopod of deep red, slightly red and pale colour groups of adult shrimps of Neocaridina denticulata were captured photographically and analysed digitally. Chromatophores in the deep red group were the strongest in colouration and sizes. The chromatophores on the anterior parts of the shrimp body (i.e. carapace and somite) were bigger in sizes and stronger in colour than in the exopod. The exopod was the most suitable area to perform pigmentation monitoring over the shrimp’s body surface.
In the second experiment, diets containing three different carotenoid sources: natural (Phaffia yeast) and synthetic astaxanthin and a synthetic □-carotene and two concentrations (80 and 160 mg kg-1) in combinations were fed to juveniles shrimps of N. denticulata for 5 weeks. DIAP method was applied on the examination of morphological and chromatic parameters of chromatophores of the resulting shrimp. Either natural or synthetic astaxanthin at 160 mg kg-1 were effective in enhancing morphological and colour change in the chromatophores of the shrimp. β-carotene was less effective in pigmentation. Pigment deposition reached saturation after 3 weeks’ supplementation of carotenoid since the change in hue, redness, and dispersion of chromatophores had been greatly reduced. The new application of DIAP demonstrated to be a useful and precise tool in the study of chromatophores and colour in aquatic animals.
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