豆粕替代鱼粉并添加有机酸对凡纳滨对虾生长、免疫和肠道菌群的影响

Effects of dietary fish meal replaced by soybean meal and supplemented with different organic acids on growth,immunity and intestinal microflora of Pacific white leg shrimp Litopenaeus vannamei

为研究低鱼粉饲料中添加有机酸对凡纳滨对虾Litopenaeus vannamei生长、免疫和肠道健康的影响,以初始体质量为(7.54±0.40)g的凡纳滨对虾为研究对象,将720尾对虾随机分成6组,每组设3个平行,每个平行40尾虾,试验设正对照组[含24%鱼粉、18%豆粕(均为质量分数,下同),为高鱼粉组]和负对照组(含18%鱼粉、36%豆粕,为低鱼粉组),在负对照组饲料基础上分别添加0.3%柠檬酸钠、0.3%丁酸钠、0.3%丙酸钠和0.3%延胡索酸,养殖周期为42 d。结果表明:与正对照组相比,负对照组凡纳滨对虾的增重率(WGR)、特定生长率(SGR)均显著降低(P<0.05),饲料系数显著升高(P<0.05),而添加0.3%丁酸钠和0.3%柠檬酸钠后,对虾SGR和WGR均显著高于负对照组(P<0.05),FCR显著低于负对照组(P<0.05),添加0.3%丙酸钠和0.3%延胡索酸后,对虾WGR和SGR与负对照组无显著性差异(P>0.05);与正对照组相比,负对照组中对虾的免疫力下降,而添加0.3%柠檬酸钠和0.3%丁酸钠后,对虾血清酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、溶菌酶(LSZ)和超氧化物歧化酶(SOD)活性较负对照组显著提升(P<0.05),而丙二醛(MDA)含量显著降低(P<0.05),血清ACP活性及MDA含量与正对照组无显著性差异(P>0.05),添加0.3%丙酸钠后血清MDA含量较负对照组显著降低(P<0.05),添加0.3%延胡索酸后血清溶菌酶活性显著高于负对照组(P<0.05),但ACP、AKP、SOD活性较负对照组降低(P<0.05);各组凡纳滨对虾肠道内容物的Alpha多样性指数无显著性差异(P>0.05),负对照组中放线菌门丰度下降,而添加0.3%柠檬酸钠后双歧杆菌和类杆菌的相对丰度较其他组显著提高(P<0.05),添加0.3%丁酸钠后梭杆菌的相对丰度较其他组显著提高(P<0.05)。研究表明,低鱼粉饲料中添加有机酸能够提高凡纳滨对虾的生长和免疫能力,调节肠道微生物平衡,其中添加0.3%柠檬酸钠和0.3%丁酸钠时效果最佳。

A feeding trial was conducted to study the effects of dietary organic acids on the growth and intestinal health of Pacific white leg shrimp Litopenaeus vannamei fed low fish meal diets.Pacific white leg shrimp with initial body mass of(7.54±0.40)g were randomly reared into 18 cages of each 100 cm×100 cm×150 cm at stocking rate of 40 individuals per cage and fed diets containing 24%fish meal(positive control group),18%fish meal(negative control group)and 18%fish meal diets supplemented with sodium citrate,sodium butyrate,sodium propionate and fumaric acid,respectively,at a dose of 0.3%at water temperature of 24-30℃for 42 days.Results showed that there were significant reduce in weight gain rate(WGR)and specific growth rate(SGR)and significant increase in food conversion ratio(FCR)in the negative control group compared with the positive control group(P<0.05).The SGR and WGR were shown to be significantly increased and FCR was found to be significantly decreased(P<0.05)in the Pacific white leg shrimp fed the diets containing 0.3%sodium butyrate and sodium citrate,without significant differences in the WGR and SGR in the Pacific white leg shrimp fed the diets containing 0.3%sodium propionate and fumaric acid(P>0.05).The shrimp in the negative control group had significantly lower immunity compared with the shrimp in the positive control group(P<0.05),and improved immunity when the shrimp fed the diets containing 0.3%sodium citrate and sodium butyrate,with increase in the activities of serum acid phosphatase(ACP),alkaline phosphatase(AKP),lysozyme(LSZ)and superoxide dismutase(SOD),and decrease in the malondialdehyde(MDA)content,the activities of serum ACP and the MDA content being not significantly different from the shrimp in the positive control group(P>0.05).There were lower serum MDA content in the shrimp fed the diets containing 0.3%sodium propionate(P<0.05)compared with the shrimp in the negative group,increased the activities of serum LSZ(P<0.05)and decreased the activities of serum ACP,AKP,SOD(P<0.05)in the shrimp in 0.3%fumaric acid group.There was no significant difference in Alpha diversity of the shrimp intestinal flora in each group(P>0.05).The decrease in abundance of Actinomycota was observed in the negative control group,while the decrease in abundance of Actinomycota,as well as the abundance of Bifidobacterium and Bacteroides,was improved in the shrimp fed the diets supplemented with 0.3%sodium citric(P<0.05).The abundance of Fusobacterium was also found to be increased in the shrimp fed the diets supplemented with 0.3%sodium butyrate(P<0.05).The findings indicate that the low fish meal diet supplemented with organic acids led to improve the growth and immune capacity of Pacific white leg shrimp,and regulated the balance of intestinal microorganism,among which 0.3%sodium citrate and 0.3%sodium butyrate had the best effects.