Studies Of Dietary Lipid Sources On The Growth Of Hybrid Sturgeon (Acipenser Baeribrandt?×A. Schrenckii Brandt(?))

Sturgeon culture is growing world-wide and mostly distribute in the northern hemisphere. China has become the largest producer of sturgeon since 2000. Hybrid sturgeons are a dominant culture object due to its rapid growth rate and strong resistance to disease, and hybrid sturgeon of Acipenser schrenckii ?× Acipenser baeri(?) is one of the most common hybrid varieties in China.At present, the commertialfeeds of sturgeon refer tothose of Salmonoids, but Salmonoids are cold water fish and lipid contents in their feed is relatively high,in order to meet the high energy demand of Salmonoids. While high lipid levels of feed will deposite fat in sturgeons' liver and cause hepaticdysfuntion. The present study aimed at to evaluate the appropriate lipid level in sturgeon's diets and to study the effect of partial or total fish oil substitution by different plant oil on growth performance,feed digestibility, serum antioxidant status and fillet fatty acid composition in juvenile hybrid sturgeon, in order to find out the appropriate types and proportionof plant oil.At first, four experimental diets A, B, C and D were formulated with increasing lipid levels(5.00, 10.00, 15.00 and 20.00%) using fish oil. Final body weight (FBW), weight gain rate(WGR),specific growth rate (SGR) andfeed efficiency (FE) of fish fed dietsCwere significantly higher than those of fish fed diet A, B and D(P <0.05). But feed intake (FI) in C fish group significantly lower than A and D fish groups (P <0.05).The results also showed that total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and myeloperoxidase (MPO) increased when dietary lipid levels increased from 5% to 15%;significant difference was presented between D5 and D15fish groups (P <0.05).These findings suggested that the supplementation of lipid being 15% showed considerable improvement in the growth, apparent digestibility of lipid and energy, serum antioxidant capacity of hybrid sturgeon.Secondly, a 12-week feeding trial was carried on to evaluate the effect of partially or totally replaced dietary fish oil on feeding, growth performance, serum biochemical indicators and fatty acid metabolism of hybrid sturgeon.The results showed that FE fed diet E significantly higher than diet A fish group (P <0.05) and FI fed diet E was the lowest in the four groups. MUFA and PUFA in diet E was significanltly higher than other groups(P <0.05).The result suggested that totally replacing fish oil with linseed oil had no negetive affecting on the commodity value of hybrid sturgeon.Finally, the evaluate effects of replacement of fish oil by plant oil blend (controlgroup A feed add anchovy fish oil. B, C and D group respectively instead of fish oil with 75% linseed oil+25% soybean oil,50% linseed oil+50% soybean oil and 25% linseed oil+75% soybean oil) on flesh quality of hybrid sturgeon suggested thatit would be better to use 75% linseed oil+25% soybean oilto repacefish oil. WGR, FBW and SGR of fish fed diet B were better than other four groups.And ?PUFA and ?n-3 were also significantly higher.These researches suggested that the proper lipid level in hybrid sturgeon diets is about 15%. Hybrid sturgeon could use plant oil very well. It is better to use blend oil in order to keep the quality of hybrid sturgeon flesh.