饵料锰含量对凡纳滨对虾亚成虾生长及抗氧化活力的影响

[目的]明确凡纳滨对虾亚成虾饵料中锰(Mn)的适宜添加量,为对虾饵料的科学配制提供参考依据.[方法]以一水硫酸锰(MnSO4·H2O)为Mn源,设6个不同Mn添加量的饵料处理组:0(对照)、50、100、150、200和300 mg/kg,投喂凡纳滨对虾亚成虾(初始体重4.83±0.39 g/尾,初始体长8.23±0.43 cm/尾)10周后测定其生长性能和抗氧化活力指标.[结果]饵料Mn添加量对凡纳滨对虾的存活率无显著影响(P>0.05,下同);除50 mg/kg处理组外,其他Mn添加处理组的对虾增重率和特定生长率均显著高于对照组(P<0.05,下同),且以Mn添加量为200 mg/kg的效果最佳.凡纳滨对虾血清和肝胰腺中的锰超氧化物歧化酶(Mn-SOD)和总超氧化物歧化酶(T-SOD)活力均随Mn添加量的增加呈先升高后降低的变化趋势,当Mn添加量为150和200 mg/kg时,对应的Mn-SOD和T-SOD活力均显著高于对照组;Mn添加量达300 mg/kg时,血清和肝胰腺Mn-SOD和T-SOD活力反而下降.凡纳滨对虾血清和肝胰腺总抗氧化能力(T-AOC)对饵料Mn添加量的响应与Mn-SOD和T-SOD活力基本一致,其适宜添加范围也在150~200 mg/kg.饵料Mn添加量对凡纳滨对虾血清MDA含量未产生显著影响,也未显著降低肝胰腺MDA含量,但Mn添加量达300 mg/kg时,肝胰腺MDA含量显著高于其他Mn添加处理组及对照组.[结论]饵料中添加适量的Mn可促进凡纳滨对虾亚成虾生长,并通过提高SOD活力以提高机体的总体抗氧化水平,但添加过量会在一定程度上抑制抗氧化活力,并对肝胰腺造成一定损伤.综合生长性能和抗氧化活力指标,凡纳滨对虾亚成虾饵料中的Mn适宜添加量为150~200 mg/kg.

Effects of dietary manganese amount on growth and antioxidant activities of sub-adult Litopenaeus vannamei

[Objective]Suitable dose of dietary manganese(Mn)supplementation for sub-adult Litopenaeus vannamei was studied to provide scientific basis for the formulation of L.vannamei compound feed.[Method]With MnSO4·H2O as source of Mn,six Mn supplementation doses were set:0(control),50,100,150,200 and 300 mg/kg.Sub-adult L.van-namei(initial weight 4.83±0.39 g/shirmp,initial body length 8.23±0.43 cm/shirmp)was fed different diets for 10 weeks, then growth performance and antioxidant activity were determined.[Result]Mn supplemental doses had insignificant dif-ference(P>0.05,the same below)on survival rate of L.vannamei.Weight gain(WG)and specific growth rate(SGR)of Mn treatment groups except for 50 mg/kg treatment group were significantly(P<0.05,the same below)higher that of the control,and 200 mg/kg treatment group presented the optimum effects.Activities of Mn-superoxide dismutase(Mn-SOD)and total-superoxide dismutase(T-SOD)in serum and hepatopancreas increased firstly and then went down with the in-creasing of Mn supplemental dose.Activities of Mn-SOD and T-SOD in serum and hepatopancreas were significantly higher than control group when Mn supplemental doses were 150 and 200 mg/kg;but activities of Mn-SOD and T-SOD reduced when Mn supplemental dose was 300 mg/kg.Response of total antioxidant capacity(T-AOC)in serum and hepatopancreas of L.vannamei to dietary Mn supplemental dose was consistent with activities of Mn-SOD and T-SOD,and the optimal supplemental range was 150-200 mg/kg.Mn supplementation did not significantly affect malondialdehyde(MDA)content in serum,nor did it significantly reduce MDA content in hepatopancreas.When Mn supplemental dose reached 300 mg/kg, MDA content in hepatopancreas was significantly higher than other Mn treatment groups and control group.[Conclusion]Appropriate Mn supplementation in feed can promote the growth of sub-adult L. vannamei and increase T-AOC by in-creasing SOD activity.But excessive supplementation of Mn in feed may restrain the antioxidant activity of sub-adult L. vannamei at a certain extent,and lead to damage of hepatopancreas.According to the indictors of growth performance and antioxidant activity,the suitable range of Mn supplemental dose for sub-adult L.vannamei is 150-200 mg/kg.