碩士 / 國立臺灣海洋大學 / 食品科學系 / 92 / Abstract
A growth trial was conducted to investigate the optimal dietary magnesium (Mg) requirements of juvenile hybrid tilapia (Oreochromis niloticus × O. aureus) reared in freshwater and seawater. Semi-purified diets with eight levels (0, 0.003, 0.008, 0.015, 0.03, 0.05, 0.04, 0.05 and 0.07%) of Mg (MgSO4, Showa Chemical Co., Ltd. Japan) were each fed to triplicate groups of tilapia (mean body weight 0.88 ± 0.01 g) reared in either freshwater or seawater for 8 weeks. The rearing freshwater (salinity 0 ppt) and seawater (salinity 35 ppt) contained 4 and 1,400 mg Mg/l, respectively. In freshwater group, weight gain was highest (P < 0.05) in fish fed diets with ≧0.04% Mg, followed by fish fed diets with 0.003 and 0.008% Mg, and lowest in fish fed the unsupplemented control diet. Feed efficiency was higher in fish fed diets with 0.015 and ≧ 0.04% Mg than fish fed diets with ≦ 0.003% Mg. Protein efficiency ratio was higher in fish fed diets with ≧ 0.015% Mg than fish fed the unsupplemented control diet. Hepatosomatic index was higher in fish fed diets with ≧ 0.015% Mg than fish fed diets with ≦ 0.008% Mg. Red blood cell count, white blood cell count and hematocrit value were lower in fish fed the unsupplemented control diet than fish fed diets with ≧ 0.003% Mg. Plasma alkaline phosphatase (ALP) activity was higher in fish fed diets with 0.03 and 0.04% Mg than fish fed the unsupplemented control diet. Plasma lysozyme activity was highest in fish fed diets with 0.04 and 0.07% Mg, followed by fish fed diets with 0.003 ~ 0.03% Mg, and lowest in fish fed the unsupplemented control diet. In seawater group, all these parameters were not different among the dietary groups. Analysis of weight gain, Mg concentration of whole body, scale, muscle and plasma and lysozyme activity by broken-line and whole body Mg retention by linear regression of the fish indicated that the optimum dietary Mg requirement for tilapia reared in freshwater are 0.017% ~ 0.029%, respectively. The study also suggests that no dietary Mg is required for tilapia reared in seawater.
| Identifer | oai:union.ndltd.org:TW/092NTOU5253025 |
| Date | January 2004 |
| Creators | Jing-Yi Gu, 古靜怡 |
| Contributors | Shi-Yen Shiau, 蕭錫延 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 74 |
Page generated in 0.1035 seconds