Replacement Of Fish Meal In Diets For Penaeus Monodon And The Environmental Safety Evaluation On The Commercial Feeds

1. Dietary protein requirements of juvenile black tiger shrimp, PenaeusmonodonA feeding trial was conducted to study the effects of six dietary proteincontents (36%,38%,40%,42%,44%,46%) on shrimp, Penaeus monodon,first on growth performance (weight gain, WG; specific growth rate, SGR;survival), secondly on digestive emzyme activities (protease and amylaseactivities of hepatopancreas, stomach and intestine). Shrimp (mean initialweight1.03±0.02g) were fed with the six diets in triplicate for56days. Theresults showed that shrimp fed with40%dietary protein gain the maximumWG (417.35%) and SGR (2.93%/d) values and significantly higher thanthat of shrimp fed with36%dietary protein(P<0.05), but without statisticaldifferences with other dietary proteins (P>0.05). When the dietary proteinlevel was38%, the feed conversion ratio was the lowest and significantlylower than those of shrimp fed with44%and46%(P<0.05). Body proteincontent of shrimp fed with44%dietary protein was the highest andsignificantly different from those of shrimp fed with36%,38%and42%dietary protein, respectively(P<0.05). The apparent protein digestibility ofshrimp fed with42%dietary peotein was the highest and significantlydifferent from that of shrimp fed with46%dietary protein (P<0.05). Theprotein efficiency ratio of shrimp fed with44%and46%dietary proteinswere significantly lower than those of shrimp fed with36%～42%dietaryproteins(P<0.05). The proteinase activities in hepatopancreas, stomach andintestine were fluctuated from high to low with increasing of the dietaryprotein contents. The amylase activities decreased with increasing of thedietary protein levels. Stomach amylase activities of shrimp fed with 38%～42%dietary protein were significantly higher than that of shrimpfed with36%dietary protein (P<0.05). Intestine amylase activity of shrimpfed40%dietary protein was significantly higher than that of shrimp fedwith other dietary proteins (P<0.05). Based on the regression of WG todietary protein contents, the dietary protein requirement for juvenile P.monodon is39.70%.2. Dietary lysine requirements of juvenile black tiger shrimp, PenaeusmonodonThis study was conducted to investigate the dietary lysine requirementof juvenile black tiger shrimp. Six isonitrogenous and isoenergetic test dietswere formulated containing fish meal, soybean meal and peanut bran asprotein sources and supplemented with pre-coated L-Lysine.HCl. The actuallysine content of the six diet were2.21%、2.41%、2.59%、2.87%、3.11%、3.29%. Each diet was assigned randomly to three tanks of juvenile shrimps(initial bodyweight0.78±0.01g) there times daily for56days. The resultsindicated that there were significantly differences in growth performanceand survival rate by the dietary lysine levels.(1)The weight gain ratio (WG),specific growth rate (SGR) and survival rate (SR) increased with increasingdietary lysine levels. The WG, SGR and SR of shrimp fed with D2～D6were significantly higher than those of shrimp fed with D1(P<0.05).However, no significant difference was found in WG, SGR and SR amongshrimp fed with D2～D6(P>0.05). FCR of shrimp fed D1was significantlyhigher than that of shrimp fed with D2～D6(P<0.05).(2)Whole body andmuscle protein content of shrimp fed D1diet was significantly lower thanthat of shrimp fed D2～D6diets (P<0.05). But there was no significantdifference found in whole body and muscle protein content among shrimpfed d2-d6diets (P>0.05).(3)Shrimp fed with D2-D6showed higher totalessential acid content in whole body than shrimp fed D1diet (P<0.05).(4)Based on data of WG and SGR, broken-line model regression analysisindicates that the optimum dietary lysine requirement for growth of Penaeus monodon is2.37％of diet(DM basis) or5.88％of dietary protein.3. Replacement of fish meal by mix plant proteins in diets for PenaeusmonodonA feeding trial was conducted to evaluate the maximum level ofsubstitution of dietary fish meal by various proportions of soy proteinconcentrate and peanut bran supplemented with coated lysine andmethionine for Penaeus monodon. The shrimp (mean initial weight1.27±0.02g) were assigned to the18500L of plastic cylinder and fed withsix diets containing40%crude protein and7%crude fat at a temperature of30±1.0℃for56days. The six test diets containing30%(F0,control),27%(F1),24%(F2),21%(F3),18%(F4),15%(F5) fish meal respectively. Theresults showed that the shrimp fed with F0gain the maximum WG(245.02%) and SGR (2.58%/d) values and significantly higher than those ofshrimp fed with F3～F5(P<0.05). When the shrimp fed with F1, the feedconversion ratio was the lowest and significantly lower than those of shrimpfed with F3～F5(P<0.05). The survival rate of shrimp fed with F4was thelowest and significantly lower than that of shrimp fed with F0～F2(P<0.05),but without statistical differences with other diets(P>0.05). The differentlevel of fish meal substituted by plant proteins have no significant effects onthe whole body composition of shrimp (P>0.05). When the shrimp fed withF2, the activity of SOD in hepatopancreas was the highest and significantlyhigher than that of shrimp fed with F0(P<0.05), but without statisticaldifferences with other diets (P>0.05). However the activities of ACP andLSZ in hepatopancreas had no significant difference between each groups(P>0.05). The activity of SOD in muscle was highest in F5and significantlyhigher than any other groups (P<0.05). When the shrimp fed with F1, theactivity of ACP in muscle was highest and significantly higher than those ofshrimp fed with F2～F4(P<0.05). The activity of LSZ in muscle werehighest in F4and F5and significantly higher than F0～F3(P<0.05). Basedon the data of WG and SGR, the plant feedstuffs supplemented with coated amino acids could replace dietary fish meal in P. monodon by20%and thenon-specific immunity of shrimp was enhanced with increasing of thedietary plant proteins.4. The environmental safety evaluation on the commercial feeds forPenaeus monodonWe investigated the effects of different brand commercial diets (D1、D2、D3、D4、D5、D6) on growth performance of Penaeus monodon andwater quality. Shrimp [mean initial wet weight (2.82±0.02) g] were fed withthe six diets in quintupling for60days. The results show that weight gainand special growth rate of shrimp fed with D1, D5and D6were significantlyhigher than that of shrimp fed with D2and D4(P<0.05). Feed conversionratios of shrimp fed with D5and D6are significantly lower than those ofshrimp fed with D2and D4(P<0.05). The apparent protein digestibility ofshrimp fed with D4and D5is significantly higher than that of shrimp fedwith D1~D3(P<0.05). Different diets have significant effects on the waterquality index during the rearing period. The analyzed data in20-day showsthat chemical oxygen demand value in D1treatment is the lowest andsignificantly lower than that in other diet treatments (P<0.05). The analyzeddata in40-day shows that COD values in D5and D6treatments aresignificantly lower than that in D1~D4treatments (P<0.05), the ammonianitrogen value in D2treatment is the lowest and significantly lower than thatin D3~D6treatments (P<0.05), the lowest values of total nitrogen and totalphosphorus are found in D4and D6treatments, respectively. The analyzeddata in60-day shows that the ammonia nitrogen value in D1treatment is thelowest and significantly lower than that in other diet treatments except D2treatment (P<0.05), the total nitrogen values in D5and D6treatments aresignificantly lower than that in D1~D4treatments (P<0.05), but the totalphosphorus value in D2treatment is the lowest and significantly lower thanthat in D1and D4treatments (P<0.05). The excretion rate of nitrogen in D1and D6treatments are the lowest and significantly lower than that in other diet treatments (P<0.05). The minimum value of the excretion rate ofphosphorus is found in D1treatment. In summary, the shrimp fed with D1,D5and D6get the better growth performance and D1, D5and D6diets havelighter pollution to the water.