The Study On Replacement Of Fish Meal By Yeast Extract In Diet Of Litopenaeus Vannamei

Litopenaeus vannamei is widely cultured in world especially in China, Thetotal shrimp yield of this species was more than1.2million tons in2010, fishmeal has been the most important feedstuff used as a source of protein inaquaculture feeds. The growth of cultured shrimp as well as other aquacultureproduction and the limitations in world fish meal resources, which have remainedsteady over the past decades, means that fish meal cannot be considered as alimitless and sustainable resource for aquaculture, so efforts on replacing fishmeal with other protein sources have been devoted by aquaculturists and scholarswho are interested in this topic. We replaced fishmeal by yeast extract in feed ofLitopenaeus vannamei and then detected the digestibility, growth, musclecomposition, immunoenzyme, expressions of lysozyme mRNA and Toll receptormRNA and the Vibrio-resistant ability of the shrimp, in order to provide data onthe application of yeast extract in diet of Litopenaeus vannameiThe basal diet(A) contains25%fish meal as control, five isonitrogenousisoenergic yeast extract experiment diets, which substituted15%(B),30%(C),45%(D),60%(E) and100%(F) fish meal in basal diet, were fed to theLitopenaeus vannamei respectively, the results showed that:(1): The shrimp (6.33±0.63g) of all the alternative grous displayed highapparent digestibility on dry matter (77.96%-81.21%) and high apparentdigestibility on crude protein (87.19%-92.82%). All the yeast extract dietsdisplayed higher apparent digestibility. C, E and F treatments had significanthigher apparent digestibility on dry matter than that of control (P<0.05). Theapparent digestibility on crude protein of shrimp significant elevated as theincrement on yeast extract in diet (P<0.05). The trypsinase activity inhepatopancreas of the shrimp was significantly increased as the increment ofyeast extract in diet. The lipase activity in hepatopancreas of the shrimp wassignificantly decreased as the increment of yeast extract in diet. While the peakon amylase activity in hepatopancreas of the shrimp emerged at C treatment. (2): These diets were also fed to the shrimp (7.50±0.13g) respectively and theresult showed that there were no significant difference of survival, between alternativegroups and control group (P>0.05). The weight gain (WG) was decreased as theincrement of yeast extract in diet, the feed conversion ratio (FCR) was increased asthe increment of yeast extract in diet and the FCR of60%group and100%group wassignificant higher than that of control (P<0.05). There were no significant differenceof crude protein, crude lipid, ash, total amino acids (TAA), total delicious amino acid(TDAA), total essential amino acid (TEAA), saturated fatty acid (SFA),monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA) betweenalternative groups and control group (P>0.05). But the EPA+DHA was increased asthe increment of yeast extract in diet.After42d feeding, LSZ activity in haemolymph in15%group was significanthigher than that of control (P<0.05). There were no significant difference of SODactivity in haemolymph, the expressions of lysozyme mRNA and Toll receptor mRNAin gill between alternative groups and control group (P>0.05). After challenged withVibrio alginolyticus, in24h, the cumulative mortality of60%group was significanthigher than that of control (P<0.05); in48h, the cumulative mortality of60%groupand100%group was significant higher than that of control (P<0.05); there were nosignificant difference of cumulative mortality between alternative groups and controlgroup in72h and96h (P>0.05).