Lysine,methionine and arginine requirements of juvenile Chinese mitten crab(<I>Eriocheir sinensis</I>)

Abstract

Three experiments were conducted to determine the lysine,methionine and arginine.requirements of juvenile Chinese mitten crab Eriocheir sinensis.The juvenile crab[average initial weight:Lys experiment(2.050±0.027)g;Methionine experiment(2.027±0.033)g;Arginine experiment(2.05±0.032)g]were fed amino acids test diets for 56 days with the protein source containing casein,white fishmeal,soybean meal and crystalline amino acids.The test diets contained 5 graded levels of lysine(1.58%,1.98%,2.38%,2.78% and 3.18%),methionine(0.50%,0.75%,1.00%,1.25% and 1.50%)and arginine(1.39%,2.09%,2.79%,3.49% and 4.19%)respectively.The triplicate feeding trials were conducted in fiberglass tanks indoor.Water temperature and pH were kept at(28±3.0)℃ and 7.4,respectively.The results of the lysine experiment showed crab fed diet 3 containing 2.38% lysine had the best weight gain(WG)and specific growth ratio(SGR),but no significant difference was found between the levels of 1.98%(diet 2)to 2.78%(diet 4);the whole crab fed diet 3 had significantly low moisture and significantly high protein content(P0.05).The results of methionine experiment showed crab fed diet 8 containing 1.00% methionine had significantly high WG and SGR(P0.05),no significant difference was found in other test groups;the crab fed diet 10(1.5% methionine)had significant high moisture content and low protein content of whole body(P0.05);no significant difference was found among the other test diets(diet 6 to diet 9).The results of arginine experiment showed crab fed diet 14 containing 3.49% arginine had significant high WG and SGR(P0.05);but no significant difference for the body composition of crab was found.Based on the growth response and quadratic model regression analysis of the relationship of WG with dietary Lys,Met or Arg levels,the Lys,Met and Arg requirements of juvenile Chinese mitten crab were estimated to be 2.34%,1.12% and 3.62% respectively.