Effects Of Replacement Of Squid Paste On Growth Performance,Immunity And Antioxidation Capacity Of Litopenaeus Vannamei

Litopenaeus vannameiis one of major cultured shrimpin world,and is the main shrimp breeding species in China.Squid paste is almost indispensable part of Litopenaeus vannamei feed.With the rapid growth of shrimp aquaculture,highcontentof squid paste Cadmium and offshore resources limited,the development of squid paste alternatives and technology is imperative to protect the quality and safety of shrimp products.In order to balance the fatty acids and lecithin in the feed without squid cream,this paper replaces squid paste with fish oil and lecithin,and explores the effects of dietary fish oil and lecithin levels on growth performance,immunity and antioxidation capacity and serum biochemical indexes of Litopenaeus vannamei,in order to find the optimal replacement level of fish oil and lecithin,which providesreferences and theoretical foundation for the Litopenaeus vannamei feed.This study is composed of two feeding experiments:Trail 1Effects of replacement of squid paste with fish oil on growth performance,immunity and antioxidationcapacity of Litopenaeus vannamei525 healthy Litopenaeus vannamei with an average body weight of 2.29±0.01 g are randomly divided into 5 groups with 3 replicates per group.35 shrimps in each replicate tank are reared in an indoor recirculating aquaculture system(volume 250L)for 43 d.Feed with 5% squid pasteis regarded as the control group,the other four experimental feedsare substituted 0.0%,0.5%,1.0% and 1.5% of fish oil for 5% of squid paste,respectively.The results show that there is no significant difference in protein efficiency ratio(PER)betweenshrimp fed with 1.5% fish oil feed and the control feed(P>0.05).However,the PER of other experimental groups is significantly lower than the control group(P<0.05).No significant effectis found on the other growth performance in shrimp fed with various fish oillevels(P>0.05).Shrimp fed with 0.0% fish oil showssignificantly higher muscle moisture and lower crude lipid of the whole body than thecontrol group(P<0.05),and the other body composition of shrimp and muscle has no significantdifferenceamong all treatments(P>0.05).The contents of C18: 3n-3 and C22: 6n-3 in muscle of the control group are significantly higher than those in the experimental group(P<0.05),while the content of C20: 1n-9 is significantly lower than that of shrimp fed with 1.5% fish oil(P<0.05).The content of HUFA,n-3PUFA,EPA+DHA and n-3/n-6 in muscle of shrimp fed with 1.5% fish oil are significantly higher than those of control group(P<0.05).The muscle fatty acid composition of shrimp fed with 1.5% fish oil is the best in all treatments with fish oil.The content of serum total protein in shrimp fed with 1.5% fish oilis significantly lower than that of shrimp fed with 0.0% fish oil(P<0.05),and the content of high density lipoprotein(HDL)is significantly lower than that of control group(P<0.05).There is no significant effect on immune activity of shrimp fed with different fish oil(P>0.05).The activity of superoxide dismutase(SOD)ofshrimp fed with 1.5% fish oilis significantly higher than that in other experimental groups(P<0.05),but there is no significant difference among the othertreatments(P>0.05).The capacity of glutathione peroxidase(GSH-Px)in control group is significantly higher than that in other experimental groups(P<0.05).The results show thatfeedwith 1.5% fish oil has better effect on the growth and antioxidation capacity.When shrimp fed with 1.0% fish oil,the composition offatty acid of muscle is close to that of the squid paste group,and the total content of EPAand DHA is the highest.Trail 2Effects of replacement of squid paste withlecithinon growth performance,immunity and antioxidation capacity of Litopenaeus vannameiA43d feeding trial is conducted to investigate the effects of dietarylecithin on growth performance,immunityand antioxidation capacity of Litopenaeus vannamei.525 healthy shrimpswith initial average body weight of 2.29±0.01 g are randomly stocked into 5 groups in re-circulated water system.Each group ha s 3 replicates and each tank has35 shrimps.Feed with 5% squid pasteis regarded as the control group,the other four experimental feedsare substituted 0.0%,1.0%,2.0% and 3.0% of soybean lecithin oil(theproportion of lecithin is 60%)for 5% of squid paste,respectively.The results show that the addition of different levels of lecithin has no significant effect on the growth of Litopenaeus vannamei compared with the control group(P>0.05).Shrimp feed with 0.6% lecithin has the lowest moisture content and the highest crude protein content,and there is no significant difference compared with the control group(P>0.05).These contents of C20: 0,C20: 0,C20: 5n-3 and HUFA in muscle of shrimp fed with 1.2% lecithinare the highest in all treatments,however,compared with the control group,no significant difference is found in the contents of C22: 6n-3 and n-3PUFA(P>0.05).The content of serum low density lipoprotein(LDL)in shrimp fed with 1.2% and 1.8% lecithin group is significantly lower than that of control group(P<0.05),and there is no significant difference between the two groups(P>0.05).There is no significant difference in the capacity of alkaline phosphatase(AKP)between shrimp fed with 1.2% lecithin and control group(P>0.05).The capacity of lysozyme(LZM)in serum of all the treatments is significantly lower than that of control group(P<0.05).In the hepatopancreas,the capacity of catalase(CAT)is significantly better than that of other experimental groups(P<0.05),and the content of malondialdehyde(MDA)is significantly lower than that of shrimp fed with 1.2% and 1.8%lecithinand the control group(P<0.05).The results show that shrimp fed with 0.6% lecithin has better effects on the content of crude protein and antioxidation capacity.When shrimp fed with 1.2% lecithin,the composition offatty acid of muscle is close to the squid paste group,and rich in high unsaturated fatty acids,besides that,the total content of EPA and DHAis the highest.Meanwhile,the immune capacity of shrimp fed with 1.2% lecithinis promoted.In summary,shrimp feed is substituted 1.0%,1.5% fish oil or 0.6%,1.2% lecithin for 5% of squid paste,which doesn't reduce the growth performance,feed utilization and immunity and antioxidation capacity of Litopenaeus vannamei,and can be used for the production of squid-free shrimp feed.