脂肪和蛋白质水平对工业养殖大西洋鲑消化酶、非特异性免疫及水质的影响

Digestive enzyme activities,non-specific immunities and water quality in recirculation aquaculture systems of Atlantic salmon (Salmo salar) fed diets varying in fat and protein levels

为探讨脂肪和蛋白质水平对工业化养殖大西洋鲑相关消化酶活力、免疫及对水质指标的影响,采用3×2双因素试验设计(3脂肪水平:18%、21%、24%,即F18、F21、F24;2蛋白质水平:38%、48%,即P38、P48),形成6种实验处理的膨化配合颗粒料,每处理3重复,在工业化封闭循环海水养殖(RAS)条件下,选用初重(650.0±45.50)g大西洋鲑720尾进行56 d的养殖实验。结果显示:(1)F21可显著提高大西洋鲑胃、肠、肝脂肪酶活力,比低脂肪分别提高11.52%、14.63%、4.31%;P48使肠、肝胰蛋白酶活力分别提高8.23%、8.33%,且发现其活力水平远高于胃蛋白酶。(2)F18、P48可显著提高肠道AKP酶活力,F18比F21、F24分别提高18.61%、31.70%,P48比P38提高13.69%。(3)F21、F24可显著改善血清的抗氧化能力,F21比F18的SOD活力提高10.32%,同时MDA含量降低4.49%;P48有利于提高血清LZM活力及补体C3含量,P48比P38分别高9.49%、5.93%。(4)低蛋白质水平可显著降低水体中氨氮、硝酸盐的含量,P38比P48分别降低61.70%、28.36%;提高脂肪水平可降低水体氨氮含量,F21、F24比F18分别降低10.00%、8.20%。研究表明,饲料脂肪和蛋白质水平与消化吸收酶、非特异免疫、养殖水氨氮之间关系特征明显;适当提高脂肪水平有利于提高消化道脂肪酶活力,提高蛋白质水平有利于提高免疫力;低蛋白质和中高脂肪组合可有效降低大西洋鲑的氨氮排泄量。

The 3 × 2 two factors random animal experiment was conducted for 56 days to evaluate the effects of dietary fat and protein on digestive enzymes activities in alimentary canal and liver, nonspecific immunity of Atlantic salmon and the water environment reared at recirculation aquaculture systems （RAS）. The trial fish（ initial weight 650±45.5 g）were randomly allocated into 6 triplicated treatments and fed six kinds of diets in a factorial design containing three fat levels （ 18% , 21% , 24% , labeled as F18, F21, F24 ） and two protein levels （ 38 % ,48 % , labeled as P38, P48 ）. Results show that ： （ 1 ） the stomachal, intestinal and hepatic lipase activities in medium fat level were significantly higher than that in low fat level by 11.52% （P 〉 0.05）, 14. 63% （ P 〈 0.05 ）, 4. 31% （ P 〉 0.05 ） respectively ; trypsin showed much higher activity than pepsin in gut and liver, and activities of trypsin in gut and liver were enhanced at high protein level by 8.23 % （ P 〉 0.05 ） and 8.39 % （ P 〈 0.05 ） ; （2） diet low fat and high protein levels could be good to promote the intestinal canal AKP activity of Atlantic salmon,intestinal AKP activity was significantly improved at low fat level by 18.61% ,31.70% （P 〈 0.05）than that at high and medium fat levels respectively, and was also enhanced by high protein level by 13. 69% （ P 〈 0. 01 ）. （ 3 ） Atlantic salmon had a highest serum SOD activity at medium fat level and a lowest MDA activity at high fat level;high protein level was beneficial to increase the serum LZM activity and C3 concentration by 9.49% （ P 〉 0.05 ） and 5.93% （ P 〈 0.05 ）. （4） diet low protein level can significantly reduce the content of ammonia nitrogen and nitrate in water by 61.70% （P 〈 0.05 ） and 28. 36% （P 〈 0.01 ）, diet high fat level could reduce water ammonia nitrogen content by 10.00% （ P 〉 0.05 ） and 8.20% （ P 〉 0.05 ） than medium and high level. This research revealed that appropriately increasing diet fat level could benefit the lipase activity,increasing diet protein level could benefit immunity, and the combination of low protein and high fat could effectively reduce the ammonia nitrogen excretion of Atlantic salmon.