FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

This study compared the effect of amino acids (L-methionine, L-proline, betain hydrochloride) fortified test diets containing graded levels of soy-protein for juvenile cobia. In the test of adding one amino acid to pure soy-protein diet as a feeding stimulant, the results showed that the best feed intake rates were 1.84% for L-methionine replaced at level of 1.5%, 4.57% for L-proline replaced at level of 1.15% and 1.35% for betain hydrochloride replaced at level of 0.14%.Fortified amino acids (L-methionine, L-proline, betain hydrochloride，2 : 1 : 0.1) as feeding stimulants were added to soy-protein replacement diets to find the best substitute level for juvenile cobia. The results showed the survival rate still maintain at 100% when the fish fed with diets of soy-protein replaced at levels of 20%, 60% and 80% for 3 weeks period. The highest feed intake rate was 6.2% when fish fed with diet of soy-protein replaced level at 0% and the lowest feed intake rate was 1.8% when fish fed with diet of soy-protein replaced level at 100%. However, the best weight gain and feed conversion ratio (FCR) occurred at soy-protein replaced level at 20%. They were 263% and 0.88, respectively.The results suggested that using amino acids as feeding stimulants added to soy-protein based diet at level of 20% could get the best feed intake, survival, weight gain and FCR results.