Effects Of Rhodotorula Mucilaginosa On Growth, Digestive Enzyme Activity, Immunity Of Litopenaeus Vannamei, Oreochromis Niloticus And Trachinotus Ovatus

1. Ingredients of R. mucilaginosaFermented product of R. mucilaginosa was mainly consisted of81.17%moisture,9.27%crude protein (CP) and4.2%total sugar. It was rich in β-glucan (1.3%),β-carotene (1.4mg/kg), astaxanthin (1.0mg/kg) and vitamin E (172mg/kg). It had thepotential to be feed additive.2. Effect of R. mucilaginosa on growth, immunity of Litopenaeus vannamei56days growth experiment of L. vannamei (3.4±0.048g) was conducted using6experiment diets (CP,38%) formulated by adding different levels of R. mucilaginosa tobasal diet:0%(control),0.25%,0.5%,1%,2%, and4%, respectively. The resultsshowed that the final average weight in group0.5%were higher than that of othergroups and markedly higher than that of group2%(P<0.05). There were no signicantdifferences of specific growth rate (SGR), weight gain(WG) and feed conversation rate(FCR), survival rate, hepatopancreas index (HSI) and moisture, cash, crude fat of L.vannamei among each group(P>0.05). The CP of L. vannamei in group2%wassignificantly higher than that of control group (P<0.05). The tendency of serumlysozyme activity (LSZ), superoxide dismutase activities (SOD) in serum andhepatopancreas decreased first and then increased. Activity of them in group0.50%wasobviously lower than those of other groups (P<0.05). The serum phenoloxidase activityactivities (PO) in groups0.25%,2%, and4%were obviously higher than that of controlgroup (P<0.05).3. Effect of R. mucilaginosa on growth, digestive enzyme activity and immunity ofOreochromis niloticus56days growth experiment of O. niloticus (5.22±0.01g) was carried out using6experiment diets(CP,31.2%) which were formulated by adding0‰(control),1‰,2‰,3‰,4‰, and5‰of R. mucilaginosa to basal diet, respectively. The results was thatthere were no markedly differences of SGR, WG and the final average weight amongeach groups (P>0.05). FCR in groups2‰and4‰were obviously lower than that ofgroup control (P<0.05). HSI in group4‰was remarkably lower than that of group1‰(P<0.05). CP of O. niloticus in groups1‰and2‰were significantly higher than thatof group5‰(P<0.05). Cash of O. niloticus in groups1‰and3‰were markedly lower than that of the control group (P<0.05). The protease activities of stomach, liverand foregut in group1‰, of midgut in group2‰, of hindgut in group3‰wereobviously higher than those of other groups（P<0.05）. Amylase activity of stomach andliver in group2‰were remarkably higher than that of group contro（lP<0.05）. Amylaseactivities of foregut in all experimental groups were significantly higher than that of thegroup contro（lP<0.05）and that in group3‰was highest. Amylase activities of midgutin groups1‰to3‰were obviously higher than those of the control group and group5‰（P<0.05） and that of the group1‰was highest.Amylase activity of hindgut in group5‰was markedly higher than that of the group control（P<0.05）. There were nosignificant differences among each treatment groups of stomach lipase（P>0.05）. Lipaseactivity of liver in group5‰, of foregut in groups4‰and5‰and of midgut andhindgut in groups1‰to3‰was markedly higher than those of other groups, of thegroup control and1‰, and of the group control and4‰（P<0.05）, respectively. LSZand nitric-oxide synthaseactivity(NOS) of liver in group3‰were obviously lower thanthose of the group2‰（P<0.05） and significantly higher than those of other groups（P<0.05）.4. Effect of R. mucilaginosa on growth, digestive enzyme activity and immunity ofTrachinotus ovatus56days experiments of T. ovatus (16.66±0.13g) was conducted using6experiment diets (CP,41.38%), which were composed by adding0‰(control),1‰,2‰,3‰,4‰, and5‰of R. mucilaginosa to basal diet, respectively. After8weeks offeeding, fish were infected with Vibrio harveyi by intraperitoneal injection (IP).Survival rate was recorded and the levels of complement3/4(C3/4) andimmunoglobulin M (IgM) in serum were investigated. The results showed that the finalaverage weight, WG, SGR in group1‰were obviously higher than those of othergroups (P<0.05). FCR in groups1‰and5‰was significantly higher than that of group3‰(P<0.05), but not markedly different with that of group control (P>0.05). HIS ingroups1‰to4‰were significantly lower than that of group control (P<0.05), butthere were no remarkably difference of viscerosomatic index and condition factoramong each groups (P>0.05). CP in group2‰and1‰were significantly higher thanthose of other groups (P<0.05). There were no significant differences of pepsin andintestinal lipase among each group (P>0.05). Trypsin in the test groups were remarkablyhigher than that of group control (P<0.05). Stomach amylase decreased with increasingadjunction of R. mucilaginosa, on the contrary, amylase in the liver and intestinalincreased (P<0.05). Serum LSZ, alkaline phosphatase activity, IgM and C3increasedwith increasing addition of R. mucilaginosa. NOS activity and C4in serum had the contrary tendency. Liver MDAin group1‰was significantly higher than those of othergroups (P<0.05). C3in groups control and1‰between3h and12h after IP infectionwere remarkably higher than that before IP infection (P<0.05). But C3in group2‰to5‰were markedly higher than that of0h until6h (P<0.05) and decreased quikly at48h.C4in groups control and1‰at3h was significantly higher than that of0h (P<0.05).C4in groups2‰and3‰and groups4‰and5‰was obviously higher than that of0hat6h and12h, respectively(P<0.05). C4at48h in each group was still significantlyhigher than that of0h (P<0.05). IgM between0h to48h in each group wassignificantly higher than that before IP infection (P<0.05). Survival rate in group1‰was100%and that in group3‰to5‰was lower than that of group control.To conclude, R. mucilaginosa could promote the gowth of L. vannamei, O.niloticus and T. ovatus, the digestive enzyme ability of fish. The surggested addingdosage of R. mucilaginosa in the feed of them was5‰,1.75‰and0.5‰, respectively.