不同养殖模式对尼罗罗非鱼生长、免疫性能及水质的影响

Comparison of Growth Performance,Immune Activity of Nile tilapia (Oreochromis niloticus) and Water quality in Two Aquaculture Systems

为探讨循环水养殖模式(RAS组)和池塘养殖模式(池塘组)对尼罗罗非鱼(Oreochromis niloticus)生长、免疫性能及水质影响的变化规律,开展了为期8周的养殖试验。结果表明:(1)RAS组中鱼体增重率(WGR)[(597.36±169.79)%]显著高于池塘组[(470.98±142.99)%](P<0.05),饲料转化率(FCR)[(1.17±0.02)%]却显著低于池塘养殖系统[(1.47±0.03)%](P<0.05)。特定生长率(SGR)和肥满度(CF)也高于池塘养殖系统,但差异不显著(P>0.05);(2)在第4周和第8周分别测定了鱼体胃和肠中消化酶活性,第4周时,RAS组中肠蛋白酶活性值[(1 387.56±278.43)μg/(g·min)]显著高于池塘组[(1 129.99±382.67)μg/(g·min)](P<0.05);第8周时,肠脂肪酶活性[(18.11±4.28)μg/(g·min)]显著高于池塘组[(12.89±8.00)μg/(g·min)](P<0.05);(3)在第4周和第8周分别测定了鱼体肝胰脏、头肾和血清中碱性磷酸酶(ALP)、溶菌酶(LSZ)和总超氧化物歧化酶(T-SOD)活性,整体表现为RAS组免疫性能低于池塘组;(4)每周测定水体氨态氮和亚硝态氮含量显示,RAS组氨态氮维持在0.0067~0.0212 mg/L,亚硝态氮含量为0.0027~0.0087 mg/L,均低于池塘组。

The growth performance and immune activity of Nile tilapia（ Oreochromis niloticus） were measured and water quality was monitored during an 8-week experiment（ Sep 4-Oct 28,2015） that compared a recirculating aquaculture system to a pond system. Nile tilapia [（ body length（ 9. 47 ± 4. 24） cm,body weight（ 24. 57 ±9. 56） g] were randomly selected for the two treatment groups： a recirculating aquaculture system（ RAS） group and a pond system（ PS） group. Each group contained 120 individuals and the experiment was run in triplicate. In both systems,dissolved oxygen（ DO） remained above 3 mg/L,the p H range was 7. 0-8. 5 and the water temperature range was 24. 6-30. 9℃. Fish were fed twice daily at 09 ∶ 30 and 16 ∶ 30 and pond water was exchanged twice weekly at 20%-30%,a typical exchange rate in ponds. At the end of the test,the body length and weight of Nile tilapia were measured and the specific growth rate（ SGR,%/d）,weight gain rate（ WGR,%）,condition factor（ CF） and feed conversion ratio（ FCR,%） were calculated for each system. Results show：（ 1） The WGR in the RAS group（ 597. 36 ± 169. 79） % was significantly higher than that（ 470. 98 ± 142. 99） % of in the PS group（ P〈 0. 05）,whereas the FCR（ 1. 17 ± 0. 02） % in the RAS group was significantly lower than that（ 1. 47 ±0. 03） % of in the PS group（ P〈 0. 05）. The SGR and CF were higher in RAS group but the differences were not significant.（ 2） Digestive enzyme activity in the stomach and intestine for the two aquaculture systems were determined at week 4 and 8 and the intestine protease activity of Nile tilapia in the RAS group（ 1 387. 56 ±278. 43） μg/（ g·min） was significantly higher than that（ 1 129. 99 ± 382. 67） μg/（ g·min） in the PS group at week 4（ P〈 0. 05） and the intestine lipase activity in RAS group（ 18. 11 ± 4. 28） μg/（ g·min） was significantly higher than that（ 12. 89 ± 8. 00） μg/（ g·min） for the PS group at week 8（ P〈 0. 05）.（ 3） Alkaline phosphatase（ ALP）,lysozyme（ LZM）,and the total superoxide dismutase（ T-SOD） in the hepatopancreas,kidney head and serum were also determined at week 4 and 8 and the immune activity of Nile tilapia in the RAS group was lower than for the PS group.（ 4） Ammonia and nitrite were measured weekly and the ammonia concentration range in the RAS group was 0. 0067-0. 0212 mg/L and the nitrite range was 0. 0027-0. 0087 mg/L,both significantly lower than in the PS group. Our results show that growth performance was higher,the functionality of the immune system was lower and water quality was better in the RAS group. This study lays a scientific basis for promoting wide adoption of the recirculating aquaculture system for raising Nile tilapia.