碩士 / 國立臺灣海洋大學 / 水產養殖學系 / 105 / Abstract
The aim of this study was to investigate the effect of feeding of commercial feeds and fresh duckweed on the growth of the fish, growth of the duckweed and its impact in water quality. The experiment is divided into two parts;(1) the duckweed to replace commercial feed, its effect on growth of Red tilapia and in water quality (2) different size of Red tilapia- duckweed fish symbiotic effect in duckweed growth and in water quality.
For experiment 1, the purpose of the study was to evaluate the use of duckweed as a replacement of the commercial feed on the fish growth and its effect in water quality. The experiment has three treatments with 3 replicates. Group A for 7 days feeding with commercial feed (no duckweed cage culture), group B and C, both fed with 6 days commercial feed and 1-day fresh duckweed. The difference between the two was for group B no duckweed cage culture inside the tank while group C has. Feed and fresh duckweed (CP: 35.00%; moisture: 92.5%) were fed at 3% of the body weight of the fish. Treatments were fed with the same protein content of 35.83%. Duckweeds was collected once a week (1/2 of the production area). The initial weight of fish was 4.9 ± 0.91 g and cultured for 12 weeks. The results showed that, there were significant differences in food conversion rates between the three groups, which were 2.25, 6.47 and 6.35, respectively. No significant difference was found in total final weight (TFW), total weight gain (TWG), survival rate (SR), feed conversion rate (FCR) and protein efficiency ratio (PER). The results showed that a day of feeding fresh duckweed will not cause growth differences. In terms of water quality, significant differences were found in total ammonia nitrogen (TAN), nitrite (NO2-N), nitrate (NO3-N) and phosphate (PO4-3). It indicates that, the existence of duckweed in the system can effectively reduce the nutrients in the water.
For experiment 2, the purpose was to evaluate the effect of different sizes of Red tilapia with the same biomass on the growth of duckweed and in water parameters. Treatments were consisted of two fish sizes: small (8 fish, average body weight: 5.61±2.38g) and medium-sized fish (4 fish, average body weight: 11.20 ±1.17g) with 3 replicates. The experiment was performed with 5 days feeding of commercial feed, 1-day feeding of fresh duckweed and 1-day without feeding and carried out for 8 weeks. The duckweed was collected once a week (1/2 area) and production was recorded. The results showed that, the small-sized fish group had the better growth performance in terms of TFW, TWG and SGR. Medium-sized fish group had the poor FCR and lowest PER. No difference was found in SR. For duckweed growth, small-sized fish had the highest duckweed production. No significant differences were also found among the water parameters, indicating that the nutrients produced by fish are still in the range of absorption capacity of duckweeds.
In conclusion, the feeding of commercial feed with duckweeds will not affect the growth performance of the fish. For the duckweed production, small-sized fish was recommended and the best choice.
| Identifer | oai:union.ndltd.org:TW/105NTOU5086034 |
| Date | January 2017 |
| Creators | Chou, Wei-Hsueh, 周煒學 |
| 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 | 59 |
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