| Water environment and diatary are major effect factors affected fish quality. Fish stocking in natural water and culture in pond have significance differences in muscle quality, taste and morphological appearance. Silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys mobils) are the main fish economic importance in China. In order to elucidate the differences and their reasons of muscle quality, taste and morphological appearance of fish live in different environments. We sampled the silver carp and bighead carp from three different environment conditions, including living in the Three Gorges Reservior, stocking in water ranch, and rearing in farm pond, then compared their meristic characters, diatary, digestive enzyme activity and muscle nutritional quality. The main findings are as follows:1. The food compositions of three groups silver carp and bighead carpIn this study, the food component compositions of the three groups of silver carp were divided into three categories (phytoplankton, debris, sediment), the largest share was debris. The algae of reservoir group and stocking group of silver carp was mainly composed of bacillariophyta, the algae of culture group was mainly composed of Cyanophyta. The algae of reservoir group and stocking group of bighead carp was mainly composed of bacillariophyta, the algae of culture group was mainly composed of bacillariophyta chlorphyta.The results of comparing on activities of protease, amylase and lipase in intestine of three groups of silver carp showed that the activities of three digestive enzymes in intestine of culture group were significantly higher than reservoir group and stocking group, but no significant difference between reservoir group and stocking group. The results of comparing on activities of amylase and lipase in intestine of three groups of bighead carp showed that the activities of two digestive enzymes in intestine of culture group were significantly higher than reservoir and stocking group, but no significant difference between reservoir and stocking group. The activities of protease of stocking group had no significant difference with culture group and reservoir group.2. Evaluation of muscle nutrition quality and nutrient compositonss in three groups of silver carp and bighead carpThe nutritional composition in the muscle of three groups of silver carp and bighead carp was analyzed and the nutritional quality was evaluated by conventional and biochemical analytical methods. It was showed that the content of moisture, crude ash, crude fat, crude protein, TAA of reservoir group of silver carp were78.89%,1.26%,0.63%,17.66%,86.99%(dry weight), tasty amino acids content was33.59%. The EAAI index of those essential amino acids was79.40. The content of moisture, crude ash, crude fat, crude protein, TAA of stocking group of silver carp were79.64%,1.15%,0.64%,17.61%,86.22%(dry weight), tasty amino acids content was32.22%. The EAAI index of those essential amino acids was79.09. The content of moisture, crude ash, crude fat, crude protein, TAA of culture group of silver carp were80.59%,1.13%,0.65%,16.64%,85.49%(dry weight), tasty amino acids content was32.08%. The EAAI index of those essential amino acids was78.61. The constitutional rate of the essential amino acid (EAA) of three groups of silver carp met the FAO/WHO Standard. The result demonstrated that muscle quality of silver carp of reservoir group and stocking group was better than that of culture group, all of three groups of silver carp were high quality nutritional value fishes involved in low fat content, high protein, and comprehensive amino acids.The content of moisture, crude ash, crude fat, crude protein, TAA of reservoir group of bighead carp were78.59%,1.21%,0.59%,18.60%,87.86%(dry weight), tasty amino acids content was33.90%. The EAAI index of those essential amino acids was80.71. The content of moisture, crude ash, crude fat, crude protein, TAA of stocking group of bighead carp were79.06%,1.16%,0.60%,18.27%,86.62%(dry weight), tasty amino acids content was33.33%. The EAAI index of those essential amino acids was80.14. The content of moisture, crude ash, crude fat, crude protein, TAA of culture group of bighead carp were80.63%,1.08%,0.70%,16.60%,85.49%(dry weight), tasty amino acids content was32.80%. The EAAI index of those essential amino acids was75.65. The constitutional rate of the essential amino acid (EAA) of three groups of bighead carp met the FAO/WHO Standard. The result demonstrated that muscle quality of bighead carp of reservoir group and stocking group was better than that of culture group, all of three groups of bighead carp were high quality nutritional value fishes involved in low fat content, high protein, and comprehensive amino acids.3.The meristic characters comparison of three populations of silver carp and bighead carp To investigate the difference among three groups of silver carp and bighead carp,21meristic characters were measured from60individuals by using one-way analysis of variance, cluster analysis, principle component analysis and discriminant analysis to compare them. The result of one-way analysis of variance revealed that8morphological proportional characters (6-7/body length,3-9/body length,4-6/body length,2-10/body length,2-9/body length,9-10/body length,4-5/body length,8-9/body length) were significant different among the three groups of silver carp. The result of one-way analysis of variance revealed that8morphological proportional characters (1-2/body length,2-3/body length,4-5/body length,6-7/body length,7-8/body length,3-10/body length,3-9/body length,3-8/body length,4-9/body length,4-8/body length,4-6/body length) were significant different among the three groups of bighead carp. The result of cluster analysis indicated that silver carp and bighead carp of reservoir group were more similar to stocking group morphological characters.In the result of principle component analysis of silver carp,8principal were constructed by factor loading, the cumulative contribution ratio was75.055%. In the result of principle component analysis of bighead carp,6principal were constructed by factor loading, the cumulative contribution ratio was75.224%.In discriminant analysis, there three groups of silver carp and bighead carp could be divided. The total accuracy of discriminant of silver carp from three group all was88.00%. The total accuracy of discriminant of bighead carp from three groups all was96.70%. The results showed that the attribution of three groups can be determined by differences in morphological proportional characters.In conclusion, the present results indicates that the major reasons of silver carp and bighead carp bearing better quality in natural water than that in other environment were fish muscle nutritional composition change which resulted in fish lived in diferent water quality and diatary components. Fish which was transferred from pond to natural water in certain period time was able to improve their quality and value. Fish stocking in reservoir water ranch is a potencial ecological farming mode. The present results would provide useful basic data to utilizing reservoir water, to find new ecological farming mode, to get high quality market fish, and to promote sustainable development of water ranch ecological fish farming. |
PDF Full Text Request