الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
The experimental work of the present study was carried out at the laboratory of fish Nutrition, Faculty of Agricultural, Moshtohor, Benha University. Two experiments were conducted. The first experiment aimed to evaluate the effect of different L-carnitine levels and amino acids in tilapia diets (0, 300 mg L-camitine, 10 g lysine + 5 g methionine, 15 g lysine + 7 g methionine, 10 g lysine + 5 g methionine + 300 mg L- carnitine and 15 g lysine + 7 g methionine + 300 mg L- carnitine) on growth performance, feed utilization and body composition of nile tilapia. While the second experiment aimed to study the effect of different doses of flumequine (0, 6, 8, 10, 12 mg sub therapeutic doses during 90 days and 12 mg therapeutic dose for 5 days) on growth performance, feed utilization, body composition, chromosomal aberrations and determination of flumequine residues in tissues of the same fish species. The first experiment started at 1 June 2003 and lasted until 3 August of the same year (90 days), while the second experiment was started on 1 September 2003 and lasted until 30 November of the same year (90 days) therefore twelve diets were formulated and tested in twenty four aquaria (Two replicate for each diets). Each aquarium was stocked with 25 fish of Nile tilapia for first experiment with initial weight 1.63 ± 0.07 and 20 fish for the second experiment with initial weight 13.71 ±0.41 the experimental fish were distributed randomly into the experimental aquaria.
Summary and Conclusion 86
Results of the first experiment could be summarized as follow: With regard to the effect of different L- carnitine levels and amino acids, results showed that, the diet contained (15g lysine + 7g methionine + 300 mg L- carnitine / kg basal diet) significantly increased final body weight, body length, weight gain, specific growth rate and improved (reduced) feed intake, feed conversion ratio while protein efficiency ratio was not significantly affected.
Results of proximate analysis showed that, the diet contained of (15g lysine + 7g methionine + 300 mg L- carnitine) significantly increased protein and decreased fat and ash
while dry matter content of fish flesh was not significantly affected.
Results of the second experiment could be summarized as follow:
With regard to the effect of different flumequine levels, results showed that the dose of 10 mg/kg of body weight/ day caused significant increase in final body weight, body length, weight gain, specific growth rate, feed intake. Also it improved feed conversion ratio (1.02) with the same dose whereas the other doses caused non significant change in feed conversion ratio compared with control group. Also, protein efficiency ratio increase with in significant differences between the experimental groups (the best value
1.95 was recorded by fish fed the diet with 10 mg/kg, of body weight / day).
of proximate analysis of whole fish body showed that the fish with dose 10mg/kg of body weight/ day gained the highest percentage of protein (67.34%) and the lowest percentage of moisture (76.13%), fat (11.13%) and ash
(16.03%).
Determination of flumequine residues in muscle of fish at the end of experiment after three month showed negative
results.
Flumequine at dose of 10 mg/kg of body weight! day (group 4) caused the lowest percentage in total chromosomal aberrations (5.79%) compared with the other doses (group 2, 3, 5, 6) which caused the highest percentage of total chromosomal aberration (8.32%, 7.52%, 8.7% and 8.75%, respectively).
In general conclusion, dietary L-carnitine supplementation (15 g lysine + 7 g methionine + 300 mg L-carnitine / kg / diet) improved growth and feed utilization, decrease tissue fat and increased tissue protein of Nile tilapia. Also, this study recommended the addition of flumequine to fish diets at a dose of 10 mg/kg of body weight / day as prophylactic dose in order to increase growth rate, feed utilization and decrease mortality. Fish showing negative results for antibiotic residues (flumequine), this can be attributed to the fact that fishes were withdrawed from antibiotic residues in their products after 90 days of treatment.