Effects Of Dietary Fos And Composite Additives On Growth Performance,Immune Response And Intestinal Health Of Grouper (Epinephelus Coioides)

The present experiment was conducted to investigate the effects of dietary fructooligosaccharides(FOS)alone or in combination with Bacillus Pumilus(SE5),tributyrin(Tb)and glutamine(Gln)dipeptide on growth performance,immune response and intestinal health of grouper(Epinephelus coioides).600 juvenile fish(initial weight 18.13±0.02 g)were randomly divided into 8 groups(group T1,T2,T3,T4,T5,T6,T7 and T8)with 3 replicate per group and 25 fish per replicate.The fish in each group were fed respectively for 56 d with basical diet T1(control group),or the basal diet supplemented respectively with T2(1.0×10~8CFU/g SE5+0.1%Tb and Gln dipeptide complex),T3(0.05%FOS),T4(0.1%FOS),T5(0.2%FOS),T6(0.05%FOS+1.0×10~8 CFU/g SE5+0.1%Tb and Gln dipeptide complexs),T7(0.1%FOS+1.0×10~8 CFU/g SE5+0.1%Tb and Gln dipeptide complexs),T8(0.2%FOS+1.0×10~8CFU/g SE5+0.1%Tb and Gln dipeptide complexs).The results in the trial showed as follows:(1)During the early period(day 0 to day 28),the weight gain rate(WGR)and special growth ratio(SGR)of all experimental groups were higher than the control,but not significant statistically(P>0.05).The feed conversation ration(FCR)of all experimental groups showed no significant difference with that of the control group.During the later period(day 28 to day 56),the WGR and SGR in all experimental group increased compared with the control,while those in groups T3 and T8 increased significantly(P<0.05).The FCR of all experimental groups were lower than that of the control group,but not significant(P>0.05).During the whole period(day 0to day 56),the survival rate(SR)of each experimental group was approximate 100%.The WGR and SGR of all experimental groups increased,and the WGR and SGR of group T3 increased by53.70%and 26.20%respectively compared with the control(P<0.05).The FCR of each experimental group was lower than the control group,but not significant(P>0.05).(2)The serum superoxide dismutase(SOD)activity in each experimental group was higher than the control group at days 28 and 56,and that in groups T5,T7 and T8 increased significantly at day 28 days(P<0.05),and that in group T8 was significantly higher than the control group at day 56(P<0.05).The serum lysozyme(LSZ)activities of all experimental groups were higher than the control group at days 28 and 56,and the LSZ activity of group T3increased significantly at 28 days.Serum acid phosphatase(ACP)and alkaline phosphatase(AKP)activities of all experimental groups showed no significant difference with the control group,with the exception that those in group T5 increased significantly at day 56(P>0.05).Serum glutamic-oxaloacetic transaminase(GOT)and glutamic-pyruvic transaminase(GPT)activities of all experimental groups showed no significant difference with the control group at days 28 and 56.(3)The intestinal villus height of groups T3,T5,T6 and T8 were significantly higher than the control group at day 28(P<0.05),and those in groups T4 and T8 increased significantly at day 56(P<0.05).The intestinal villus width of all experimental groups were significantly higher than the control group at days 28 and 56(P<0.05).The number of intestinal villus of groups T6,T7 and T8 increased significantly at days 28 and 56(P<0.05),and the number of intestinal villus of fish fed composite additives were generally higher than fish fed FOS alone.The intestinal muscle thickness of groups T2,T4 and T6 increased significantly at day 28(P<0.05),and those in groups of T2,T4,T6 and T8 increased significantly at day 56(P<0.05).(4)The intestinal protease activity of each experimental group was higher than the control group,and the intestinal protease activities in groups T4,T5,T7 and T8 increased significantly(P<0.05).The intestinal amylase activities of all experimental groups were higher than the control group at days 28 and 56,and that in group T8 increased significantly at days 28 and 56(P<0.05),and that in groups T5 and T7 increased significantly at day 56(P<0.05).The intestinal lipase activities of all experimental groups were higher than the control group at days 28 and 56,and that in groups T4 and T7 increased significantly at day 28(P<0.05),and that in group T8increased significantly at day 56(P<0.05),and that in composite additives groups was generally higher than that in FOS alone group.(5)PCR-DGGE techniques were used to investigate the intestinal microbiota of orange-spotted grouper after dietary administration of viable and heat-inactivated probiotics for56 d.Compared with the control group,bacteria such as Pseudomonas sp.,Vibrio sp.and Photobacterium damselae strain were present in FOS groups,while Enterobacter cloacae and Pseudomonas sp.COR294 disappeared.Compared with the control group,bacteria such as Rhodococcus erythropolis,Pseudomonas sp.,Acinetobacter junii,Cedecea sp.,Photobacterium sp.and some Uncultured bacterium,Enterobacter sp.and some Uncultured bacterium disappeared.In conclusion,dietary supplementation FOS alone or combined with SE5,Tb and Gln dipeptide could improve the growth performance,immune response and intestinal health of grouper.Moreover,the composite additives have an advantage over are FOS alone in benefitting intestinal health of fish.