Study On The Optimum Dietary Protein Level Of Juvenile Tiger Puffer, Fugu Rubripes

The experiment was conducted to study the optimum level of protein on Fugu rubripes about 16g after 45d's feeding trial ,designed by five levels of protein. White fishmeal was used as the main dietary protein source to formulate isocaloric experimental diet .300 Fugu rubripes were devided five groups at random with 6 replications and there were 10 trial in each replication. Five group protein were 34.45%,37.08%,39.83%,43,25% and 46.07%. The main results were as follows:The feeding trial showed that SGR was increasing first and then reducing with the increasing of protein content of diets. The analysis of variance showed that different feeding protein had significant effect on SGR(p<0.05), the conic model of feeding protein content and SGR is y=-0.00588x2+0.4832x-7.485(r=0.39);the highest SGR was 2.44, the homologous protein content was 41.08%;the feed intake had negative correlation with protein content: y=-0.3667x+62.038(p<0.05), which showed that the taken diet quantity was reducing with the increasing protein content. FCEdm , FCEp and FCEe were all increasing first and then reducing with the increasing of protein content of feed. There had a highest point at 39.83% protein. The analysis of variance showed that protein content of feed had significant effect on FCEdm,FCEp,FCEe of Fugu rubripes(p=0.003,p=0.0026,p=0.004).PER was increasing first and later reducing with the protein content; the relation between proein content of feed and PER was: y=-0.6393x2+50.25x-817.33(r=0.57).The nutrition composition of the fish body: The analysis of variance showed that protein content of feed has significant effect on protein content and ash content of the fish body(p<0.05);the body protein content was increasing with the increasing of feed protein content, the relation between proein content of feed and the body protein was:y=0.363x+69.70(r=0.584); there had not significant effect on water, fat and energy of the body,while fat content of body was reducing with the increasing of feed protein content .The apparent digestibility coefficients of nutrition ingredients: protein content had significant difference in Ddm and Dp(p<0.05),and Dp had positive correlations with protein content of feed: y=0.6281x+58.251(r=0.91),the result showed that Dp was increasing with the increasing of protein content when protein content of feed was between 34.45%-46.07%.Dietry protein level had significant effect on the nitrogen budget.The nitrogen budgets of different protein content of feed were shown as follows: 34.45%: 100C = 29.90G + 21.44F + 48.67U 37.08%: 100C = 28.67G + 18.57F + 52.76U 39.83%: 100C = 29.54G + 14.35F + 56.11U 43.25%: 100C = 27.98G + 14.90F + 57.12U 46.07%: 100C = 25.34G + 13.68F + 60.98UThe alimentary canal had negative correlation with protein content: y=-2.282x+266.19(r=-0.44)The result showed that the optimum protein level of Fugu rubripes is 41.64% when its avoirdupois was between 16g-50g.