Effects Of Dietary Protein Levels On The Families Of Penaeus Monodon

The feed costs account for more than half of the total cost in the shrimp feeding.Now the fish meal is the mainly protein source of shrimp feed, however, the fish mealresources are limited, so the fishmeal international market prices rose sharply, andshrimp feed costs and prices rose with the impact of fishmeal. All of these impact theshrimp farming sustainable economic and industrial development. Looking for someother protein sources to replace fishmeal to reduce the cost is a way to solve theproblem. Selecting the new shrimp varieties of low protein demanded or efficient useof dietary protein with selective breeding, is another way to solve this problem.Family selective breeding is a way to select the shrimp families that growfast fed with low protein level feed, this selective way can reduce the protein levelof the feed, save the farming cost, increase the economic benefits and will have agood application prospect. In this study, we use34%、38%and42%protein leveldiary to feed16Penaeus monodon families for8weeks, to explore the growth andsurvival of the Penaeus monodon families fed with different protein level diary.We analyzed the interaction between the Penaeus monodon families and the diaryprotein level, got the activity of amylase and protease in liver and stomach andthe changes of serum immune indicators of the Penaeus monodon families fedwith different protein level diary. The expression of growth hormone gene (GH),cathepsin-L (Cathepsin-L) gene and trypsin (Trypsin) gene in different tissueswere also studied. The main structure of the study as follows:1.The growth and survival of Penaeus monodon were significantly affected bythe dietary protein levels. Except shrimp from F14family and F15family, the specific growth rate (SGR) of Penaeus monodon increased with the increasing of dietaryprotein levels. A total of11families achieved the highest survival rate when thedietary protein level was38%, and5families achieved the highest survival rate whenthe dietary protein level was34%, while only4families achieved the highest survivalrate when the dietary protein level was42%. As the dietary protein level increased,the growth differences of the sixteen families reduced, this may indicate that thegenetic effects of shrimps in terms of growth can be revealed under lower dietaryprotein level. The interaction of SGR between families and diary protein level was notsignificant (P=0.974). The experiment selected2families(F9、F10)that grow fast fedwith low protein level diary,2families(F2、F14)that have high survival rate in eachprotein level diary group.2.With the increase of the dietary protein level, the protease activity of all thePenaeus monodon families increased, and the amylase activity of the Penaeusmonodon families descended, but the changes of amylase activity did not showobvious regularity; the protease activity of13Penaeus monodon families, liver andthe pepsin activity of14Penaeus monodon families showed significant correlationwith the families, SGR(P<0.01), the amylase activity and the families, SGR showedless correlation than the protease activity.3. With the increase of the dietary protein level, the total protein and albumincontent in blood of the Penaeus monodon increased significantly(P<0.05); the richprotein content in the diary (42%protein level)will promote the synthesis oftriglyceride and cholesterol in blood significantly(P<0.05); the immune factors inblood related with nitrogen metabolism such as aspartate aminotransferase andalanine aminotransferase also increased significantly(P<0.05) with the increase of thedietary protein level. The increase of protein level in diary showed influence toimprove the protein content of the shrimp, but no significant effect to the ash fat andother factors.4.The growth, expression of the3genes that related to the protein content in thediary showed a significant positive correlation with the protein level in diary(P <0.05).With the increase of the dietary protein level, growth difference between families andthe expression amount of the3genes reduced. The SGR and expression of the3genesof the same family fed with different diary showed significant differences (P <0.05).The SGR of9selected families was not significant interaction between families and protein level, but the expression of3genes in liver and intestinal was highlysignificant between families and protein level(P<0.01).