Utilization of amino acids in Nile tilapia [oreochromis niloticus] fry. 1- Utilization efficiency of synthetic amino acid by Nile Tilapia fry

ABSTRACT

The effect of replacing different levels of synthetic amino acids [15%, 35%, 50%, 65% and 85%] in the same proportions as in dietary casein protein on growth performance and nitrogen retention [NR] of Nile tilapia fry was investigated. The fry fed the experimental diets containing synthetic amino acids at levels 15% and 35% of dietary crude protein of casein, were significantly [P < 005] higher in the final body weight than the other treatments. The same trend was shown in average daily gain and specific growth rate. Feed conversion ratio was improved by increasing replacement of synthetic amino acid up to 35% of dietary protein casein compared to other treatments. The percentage of whole body moisture, ether extract and ash content increased significantly [P < 0.05] as the level of dietary synthetic amino acid level increased, while inverse trend was observed with percentage of whole crude protein and gross energy. The data confirm that increasing synthetic amino acids level more than the replacement level of 35% from casein in the tilapia diet affected negatively on growth and feed utilization of tilapia fry