| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 93 === To evaluate the effects of different protein sources on the growth of hybrid tilapia (O. niloticus x O. aureus), three growth trials were conducted. In the first trial, four approximately isonitrogenous (24% crude protein) and isoenergetic diets were fed to triplicate groups of 9 fish with a mean initial body weight of 1.85±0.02 g/fish and 2.41±0.06 g/fish in the brackish water and freshwater, respectively for 6 weeks. In freshwater, the weight gain was higher in the fish fed the control diet containing (FM) and lower in the fish fed diet with squid meal (SQM). There were no significant difference in weight gain for fish fed diet with shrimp meal (SM) and soybean meal (SBM). The fish fed diets containing SM and FM had higher body protein content but lower lipid than the fish fed diet with SBM and SQM. In the brackish water, the growth performance of the fish fed the test diets FM and SM was significantly (P<0.05) higher than that of the fish fed diets containing SBM and SQM. Fish fed SBM showed a significantly (P<0.05) lower growth and higher mortality than those fed the other treatments. The fish fed diet with SM had higher body protein content than those fed the other treatments. There were no differences in body lipid content among treatments. The blood osmolarity of the brackish water fish (340 mOsm/L) was higher than that of the freshwater fish (300 mOsm/L).
In second trial, five approximately isoenergetic and isonitrogenous (30% crude protein) diets containing 0%, 33%, 50%, 67%, and 100% shrimp shell meal were fed to triplicate groups of 10 fry with an initial mean weight 1.54 + 0.03 g/fish under brackish water (15 0/00) for 4 weeks. The weight gain was highest in fish fed diet without shrimp shell meal, intermediate in fish fed diets with 33%, 50%, 67% shrimp shell meal, and lowest in fish fed diet with 100% shrimp shell meal. The highest body protein content was observed in fish fed diets with 67% and 50% shrimp shell meal compared to the initial fish. The lowest body protein content was obtained with the fish fed diet with 100% shrimp shell. The tilapia fed diet containing 33% and 67% of shrimp shell meal had the highest body lipid content compared to the initial fish. There were no significant differences in body lipid content among fish fed diet with 100%, 50% and 0% shrimp shell meal. No difference in body ash content was observed among treatments.
In third trial, four approximately isonitrogenous (24% crude protein) and isoenergetic diets containing 0% murex meat meal and Celtis leave meal, 50% murex meat meal, 50% Celtis leave meal and 100% murex meat meal were fed to triplicate groups of 10 fingerlings with a mean initial weight of 9.62±0.07 g/fish for 4 weeks. Tilapia fed diet with 50% murex meat meal showed the best growth performance (97±8.62), intermediate in the control diet without murex meat meal and Celtis leave meal (93.52±2.10) followed by the fish fed diet containing 100% murex meat meal (83.52±9.79). The fish fed diet containing 50% Celtis leave meal had the lowest growth performance (51.90±6.72). The different experimental diets did not affect the protein content of tilapia body. However, fish fed the diets had slightly higher lipid deposition than the initial experiment of fish.
In conclusion, SM could totally replace FM without adverse effect on the growth of the hybrid tilapia. Fish spend more energy for adaptability in salt water. Shrimp shell meal could replace soybean meal up to 60% in a diet for hybrid tilapia fry. Murex meat meal at a 50% replacement level of soybean meal is suggested for use in pelleted feed for hybrid tilapia fingerlings in order to maximize growth performance. However, substitution of soybean meal by Celtis leave meal above 50% is not to be recommended.
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