| Part1The aim of the study was examine the effects of dietary administration ofsaccharicterpen on growth performance, body nutritional composition of juvenile turbot.Six isocaloric and isonitrogenous diets were formulated to contain graded levels(0mg/kg,25mg/kg,50mg/kg,75mg/kg,100mg/kg,200mg/kg) of saccharicterpen andnamed as D0, D25, D50, D75, D100, D200, respectively. Each diet was randomlyassigned to triplicate groups of30juveniles. The experiment was conducted in plasticcylinder tanks in an indoor recirculated feeding system for64days. Results showed that:1) Fish fed diets D25, D50, and D75showed significantly higher mass gain (MG),specific growth rate (SGR), protein efficiency ratio (PER), condition factor (CF),hepatosomatic index (HSI) and spleensomatic index (SSI)(P<0.05), and obviouslydecreased feed conversion ratio (FCR)(P<0.05). However, viscerosomatic index (VSI)and survival rate (SR) revealed no noticeable difference among all treatments（P>0.05）.2) No significant difference was found in the content of moisture and crudeprotein. The crude lipid content in dorsal muscle decreased with the increasing dietarysaccharicterpen, the crude lipid content in D100and D200was significantly lower thanthat in D0group (P<0.05). The crude ash in D25and D50groups was significantlylower than that other groups (P<0.05), D200group was significantly higher than D25,D50and D75groups (P<0.05). Saturated fatty acid content and monounsaturated fattyacid content were no significant difference in each groups with the increasing dietarysaccharicterpen（P>0.05）, Except D75group, other groups of polyunsaturated fatty acidwere significantly higher than D0group(P<0.05). In this experiment, the addition ofsaccharicterpenin can improve the growth performance, decrease body fat deposition.Quadratic regression of SGR indicated that the optimal level of saccharicterpenin in dietfor juvenile turbot is74.58mg/kg.Part2The objective of this experiment was to determine the effects of dietaryadministration of saccharicterpen on lipdiemic, the digestive enzymes activities and thestructure of foregut tissue of juvenile turbot. The basal diet was formulated using fishmeal and casein as the main protein source and fish oil as the lipid source respectively.Six isocaloric and isonitrogenous diets were formulated to contain graded levels(0mg/kg,25mg/kg,50mg/kg,75mg/kg,100mg/kg,200mg/kg) of saccharicterpen and named as D0, D25, D50, D75, D100, D200, respectively. The result showed that:1)Serum triglyceride(TG), Total-cholesterol(TCHO) and HDL-cholesterol(HDL-C)concentration decreased with increasing dietary saccharicterpen levels (P<0.05), whileno significant difference was occurred in LDL-cholesterol(LDL-C) concentration（P>0.05）.2) In all groups, trypsin and lipase activities of the intestine showed anincreasing-decreasing trend with increasing dietary saccharicterpen levels. Trypsinactivities in D75group was significantly higher than D0group (P<0.05), Lipaseactivities in D25and D50group was significantly higher than other groups (P<0.05).No significant difference was found in the amylase activity of gut（P>0.05）.3)Microvilli length, intestinal villi length and mucosal thickness of the foregut tissueshowed an increasing-decreasing trend with increasing dietary saccharicterpen levels.Microvilli length in D50group was significantly higher than other groups (P<0.05).Mucosal thickness in D50group was significantly higher than D200group (P<0.05).Intestinal villi length in D25, D50, D75, D100groups was significantly higher than D0and D200groups (P<0.05). Therefore we can draw that saccharicterpen addition caneffectively decrease lipdiemic, improve the digestive enzymes activities and thestructure of foregut tissue of juvenile turbot.Part3The purpose of this experiment was to investigate saccharicterpen on thejuvenile turbot immunity and Heat Shock Protein70content of with initialweight(55.0±0.2)g. The basal diet was formulated using fish meal and casein as themain protein source and fish oil as the lipid source respectively. Six isocaloric andisonitrogenous diets were formulated to contain graded levels (0mg/kg,25mg/kg,50mg/kg,75mg/kg,100mg/kg,200mg/kg) of saccharicterpen and named as D0, D25,D50, D75, D100, D200, respectively. The result showed that:1) Fish fed diet D50showed the highest serum lysozyme activity. Total superoxide dismutase (T-SOD)activity were significantly enhanced in fish fed diets D75, D100and D200comparedwith other treatments (P<0.05). Nitric oxide content in serum was significantly reducedwith the increased level of saccharicterpenin (P<0.05). Aspartate transaminase (AST) ofserum in D200was significantly higher than the other groups(P<0.05), but alanineaminotransferase (ALT) showed no significantly difference（P>0.05）.ALT and AST ofliver significantly decreased with the increased level of saccharicterpenin(P<0.05).There was no difference on total antioxidant capacity（T-AOC）in liver among allgroups(P>0.05). Liver malondialdehyde (MDA) content in group D25was significantlylower than that of D100(P<0.05), with no change among other groups（P>0.05）.2)HeatShock Protein70contents in serum showed no significantly difference among alltreatments（P>0.05）.3) The challenge study showed that fish fed diet D50presented lower cumulative mortality rate than other groups(P<0.05), and higher immuneprotective rate of42.31%, compared with those fed diets D25(19.23%) and D70(15.39%) after48hours, respectively. In conclusion, the addition of saccharicterpenincan improve the growth performance, immunity and disease resistance in Vibrioanguillarum. |
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