Effect Of Different Lipid Levels On The Growth Performance And Muc2,muc5b Genes Expression Of Yearlings Blunt Snout Bream Megalobrama Amblycephala

Dietary lipid plays an important role in commercial diet as a source of energy and essential fatty acids for the growth and development of fish.An 8 weeks feeding trail was conducted to evaluate the effect of dietary lipid levels on survival,growth performance and muc2,muc5b gene expression of yearlings blunt snout bream Megalobrama amblycephala.The effect of dietary lipid levels on stress,oxidative status and non-specific immune responses of blunt snout bream were also investigated respectively.Six isonitrogenous diets containing 2.29%,4.29%,6.29%,8.29%,10.29%,12.29%lipid were formulated respectively.480 healthy fish were selected and randomly divided into six groups feed by these levels diets respectively.1 Effects of dietary lipid levels on growth performance of fingerling blunt snout bream Megalobrama amblycephalaAfter 8 weeks feeding trail,the results showed that dietary lipid levels significantly effected the growth of blunt snout bream(P<0.05).The weight gains(WG)of blunt snout bream feed with dietary lipid levels 6.29%,8.29%was significantly higher than those in other groups(P<0.05).The condition factor(CF)of 8.29%group was significantly(P<0.05)higher than other groups.The feed conversation ratio(FCR)of 8.29%group were significantly(P<0.05)lower than that of the other groups,but not significantly with 6.29%group(P>0.05).The survival,ratio of viscera weight to body weight and ratio of liver weight to body weight was not significantly effected by dietary lipid levels.Based on broken-line model analyses at this study from date of FCR,the optimum dietary lipid levels was 7.61%.2 Effects of dietary lipid levels on stress and non-specific immune responses of blunt snout bream Megalobrama amblycephalaThe purpose of this study was to investigate the effects of dietary lipid levels on stress and non-specific immune responses of blunt snout bream,the serum immunological,liver antioxidant indices were measured before fishing stress and after fishing stress.After sampling fish were challenged by Aeromonas hydrophila and death rate was recorded for the next 14 days.The results showed,cortisol,ALT and AST of 12.29%group were significantly(P<0.05)higher than that of the other groups,but not significantly with 10.29%group(P>0.05).SOD,CAT,GSH GR increased with increasing of dietary lipid levels from 2.29%to 8.29%,and then of 8.29%group was significantly(P<0.05)higher than other groups.MDA of 6.29%group was significantly(P<0.05)lower than 2.29%group and 12.29%group.Cortisol,ALT and AST increased with increasing of time after fishing stress from Oh to 12h,then decrease by degrees from 12h to 24h.After challenged,fish fed lipid levels 8.29%obtained significantly(P<0.05)low death ratio,but not significantly lower than then 8.29%group(P>0.05).So it is suggested that higher or lower lipid levels may cause metabolic stress of blunt snout bream,and it might lead to the impaired liver function,depressed immunity and reduced resistance to Aeromonas hydrophila infection for this species.3 Effects of dietary lipid levels on muc2,muc5b gene expression of yearlings blunt snout bream Megalobrama amblycephala.To study the muc2,muc5b gene expression affected by different dietary lipid levels of yearlings blunt snout bream,and the muc5b gene expression affected by fishing stress for this species.By using realtime PCR analysis the muc2,muc5b gene expression in intestinal and skin respectively.The muc2,muc5b gene expression was increased in high level of lipid in feed.Muc2 gene expression of fish fed with 12.29%lipid was significantly(P<0.05)higher than that of the other groups.And muc5b gene expression of fish fed with 8.29%lipid was significantly(P<0.05)higher than that of the other groups,but not significantly(P>0.05)higher than fish fed with 12.29%lipid.The muc5b gene expression increased with increasing of time after fishing stress from Oh to 12h,then decrease by degrees from 12h to 24h.The muc5b gene expression of fish fed 10.29%lipid change significantly(P<0.05)at different time after the stress,but not significantly(P>0.05)with that fish fed with 2.29%and 6.29%lipid.Those results indicated that the high lipid level may promote the expression of muc2 and muc5b.