| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 98 === Abstract
This study investigated the effect of different levels of melamine in feed on the growth and muscle residues of hybrid tilapia, Oreochromis nilotica x Oreochromis aurea. Experiment was divided into two parts: (1) Experiment 1, 2: To investigate effect of different levels of melamine on growth of tilapia in fresh water and sea water (33 ppt), respectively. (2) Experiment 3, 4: To investigate muscle residues at single dose (500 μg/g ) melamine on tilapia grew in fresh water and sea water (33 ppt ), respectively.
Experiments 1, 2: Diets were added with melamine at 0, 0.02, 0.04, 0.06, 0.08 and 0.1 g/kg to formulate varying melamine levels at 0, 20, 40, 60, 80 and 100 μg/g , respectively (table 1). The experiment lasted for 60 days. Fish were fed to satiation twice daily. The diet composition analysis did not show any melamine in the control diet (0 μg/g ). Melamine was detected in other melamine-contained diets (20-100 μg/g ) at 21.7, 56.3, 70.2, 92.1 and 107.0 μg/g, respectively; there were no significant difference in growth performance; muscles melamine content was not detectable; survival rate was above 83 % in all treatments. In experiment 2, melamine content was detected in melamine-contained diets (20-100 μg/g ) at 24.8, 44.9, 61.2, 89.6 and 94.5 μg/g , respectively. Fish fed diet supplemented with 100 μg/g melamine had lower final weight, weight gain, SGR compared to other groups. Survival rate was above 93 % in all treatments.
Experiment 3, 4: Fish were starved for 3 days before the experiment start. The dose was given orally at 500 μg/g body weight. Muscle sampling was done at 0, 0.5, 1, 2, 3, 4, 5, 12 and 21 days after single oral dosing. Three fish were analyzed by HPLC-UV in each sampling. In experiment 3, the average oral dose for tilapia in freshwater was determined at 585.94 μg/g by using HPLC-UV. Melamine was not detectable in muscle of tilapia reared in freshwater; 0.5, 1, 2, 3, 4 and 5 days after oral administration, melamine was detected in freshwater tilapia muscle at 82.9 ± 13.4, 49.4 ± 4.1, 67.4 ± 17.2, 17.6 ± 5.3, 17.7 ± 0.8 and 6.1 μg/g , respectively. Melamine content was declining adversely with the increasing of the days. At the 12th, 21st day after oral administration, melamine was not detected in muscle of tilapia in freshwater. In experiment 4, the average oral dose for tilapia reared in seawater was determined at 658.91 μg/g by using HPLC-UV. Melamine was not detectable in muscle of tilapia in seawater in 0 day after administrated. Melamine content in muscle after 0.5, 1, 2, 3, 4, 5 and 12 days of oral administration were 71.4 ± 12.3, 48.2 ± 10.3, 44.3 ± 17.2, 21.7 ± 2.4, 22.2 ± 5.7, 15.2 ± 7.0 and 4.2 μg/g , respectively. Melamine content was declining with the increasing of the time (days). At 21th day after oral administration, melamine was not detected in seawater tilapia muscle. Half-life (t1/2) of tilapia in freshwater and seawater was 37.7 and 50.2 hours, respectively.
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