EFFECT OF D IETARY PROTEIN LEVELS ON GROWTH PERFORMANCE WHOLE BODY COMPOSITION AND INTESTINAL D IGESTIVE ENZYME ACTIVITIES OF C ICHLASOMA SP. JUVENILE

To investigate the effect of dietary protein levels on growth performance,body composition,intestinal digestivenzyme activities of Cichlasoma sp. juvenile,fish meal and soybean mealwere chosen as the main dietary protein source,nd five diets containing protein content of 37%,40%,43%,46% and 49% were prepared and fed to Cichlasoma sp.uvenile for 6 weeks. Group of -5 fish with initial bodyweight of 0. 66 gwas fed in recycling aquarium (0. 8 m ×0. 5 m ×. 5 m,-00 L ofwater volume) with aerated water. Each group was trip licate. Fish were fed 4 times (8: 30,11: 30,14:0 and 17: 30) per daywith a feeding rate of 3% -4% of bodyweight. The temperature was (-7 ±1) ℃,and dissolvedxygen (DO) content was more than 5 mg/L during the growth study. The results showed that the weight gain (WG) ofhe five group s were 868. 51%,935. 95%,1018. -8%,9-5. 16%,873. 86%,and feed conversion rate (FCR ) were. 55%,1. 48%,1. 41%,1. 47% and 1. 56%,respectively. Fish fed with 43% dietary protein had the highestWG andowest FCR. The relationship of WG and dietary protein level could be expressed with regression equation: Y (weightain,% ) = 23.277-X2+281. 84X (dietary crude protein content,% ) 2 5076. 1 (R2= 0. 83-8). In the respect ofody composition,with the increase of dietary protein,the content of crude protein and ash of whole body increased,buthe crude fat decreased. Fish fed with diet of 49% protein content had significant higherwhole body crude protein and ashontent but lower whole body crude fat content than that fed with diet of 37% protein content. There was no significantifference in whole body moisture content among all group s. Protease activities of foregut’s tissue of the five group s were40. 80 U/g,718. 03 U/g,73-. -6 U/g,686. 1- U/g,596. 51 U/g,and protease activities of foregut’s chyme were-6. 26 U/g,948. 84 U/g,141-. 43 U/g,1304. 66 U/g and 1406. 93 U/g,respectively. Liver’s GPT and GOT activi-ies (Reitman-Frankel) were 69. 89 U/g,75. 75 U/g,89. 05 U/g,91. -0 U/g,90. 66 U/g,and 140. 63 U/g,163. 08/g,181. 80 U/g,150. 65 U/g,150. 80 U/g,respectively. Results above showed that Cichlasoma sp. juvenile had theest growth performance and the highest intestinal protease activities,the highest liver’s GOT and GPT activities,whenhey fed with diet of 43% dietary protein content,which showed that the op timal dietary protein requirement for Cichlaso-a sp. juvenile was 43%.