Study On The Growth Characteristics And Energy Budget Of Penaeus Monodon Juveniles

Penaeus monodon as an excellent shrimp aquaculture species, there have scaleaquaculture in coastal area in Southern China. Currently, shrimp farming mainly use theartificial diet as a source of energy. Protein is not only the main components of the feed,but also the essential matter of composition of organic structure and normal functioning inshrimp. Life and metabolism of shrimp needs energy, it has a direct impact on aquaculturein Penaeus monodon in vivo conversion efficiency and distribution proportion. This paperstudied the effects of dietary protein levels on growth and energy budget of Penaeusmonodon juveniles, in order to providing the reference for Penaeus monodon farming,genetic breeding and nutritional study.1. According to the experimental ecology method, we designed34%,38%,42%and46%protein level diary to feed Penaeus monodon juveniles (2.27±0.55g) for42days,and measured the growth performance, digestive enzymes and energy budget. Theresults showed that the dietary protein levels significantly affected the growth and feedutilization effect of Penaeus monodon juveniles. With the increasing of the dietary proteinlevel, weight of the end (Wt), weight growth rate (WGR), protein efficiency rate (PER),specific growth rate (SGR), conversion efficiency (CE), were significantly increased, the42%dierary protein level achieved the highest Wt, WGR, PER, SGR, CE, and the lowestFCR. There was no significant difference of the protein, ash and moisture content among4samples in different dietary protein levels, there were significant differences in fat andenergy, but no significant variation. With the increasing in which feed dietary protein levelsof Penaeus monodon juveniles, the protein content overall upward trend, while the fatcontent was decline. With increasing of the dietary protein level, the activities of proteaseand amylase of Penaeus monodon juveniles significantly increased, pepsin proteaseactivity and hepatopancreas was the highest at42%protein level group, and thehepatopancreas amylase activity was highest at the46%protein level group, but the difference of stomach amylase among all groups was not significant. With increasing of thedietary protein level, CN, GN, EN, FN, UNand ANof the Penaeus monodon juvenilesshowed increasing trend, CN, FNand UNin46%protein level was significantly higher thanthe other groups. The GN, AN, GN/CNwas the highest at the42%protein level group, thedistribution of CNorder: GN> UN> FN> EN. With increasing of the dietary protein level, C(Feeding energy), G (Growth energy), F (Manure energy), U (Excretion energy) of thePenaeus monodon juveniles showed an increasing trend, and C, G, F were the highest atthe42%protein level group, U was the highest at the46%protein level group. Thedistribution of energy order: R (Respiratory energy)> G> F> U> E (Molting energy).2. Effects of seven dietary protein contents (34%,36%,38%,40%,42%,44%,46%)on growth performance and digestive emzyme activities of domestic second family (F2)generation Penaeus monodon juveniles were studied under laboratory condition. Theshrimp (2.84±0.04g) were fed with the seven diets in triplicate for48days. The resultsshowed that shrimp fed with38%dietary protein achieved the highest WG and SGR andthe lowest FCR. The shrimp fed with34%dietary protein achieved the highest PER,without statistical differences with that fed with36%,38%dietary protein, significantlyhigher than shrimp fed with40%and above dietary protein. Survival rate (SR) oflow-protein group (34%~42%) was significantly higher than that of high-protein group(44%,46%). Dietary protein content also affected the whole body composition of Penaeusmonodon juveniles. Body crude protein content increased, while body crude fat contentdecreased with dietary protein level increasing, but there was no statistical difference ofmuscle crude protein in each group. Pepsi n of shrimp fed with34%dietary protein was thehighest, with the increase of protein content, it increased first, then decreased, and thenincreased again, showed fluctuation and complementary trend with liver protease content.Amylase in stomach was higher than that in hepatopancreas, but without statisticaldifferences with stomach amylase in each group. Lipase in stomach and hepatopancreasshowed a downward trend with protein content increasing. The growth performance anddigestive enzyme activities indicated that feed with low protein level on domesticated F2generation Penaeus monodon juveniles growth was favorable, suggesting that dietaryprotein of38%was more appropriate.