饲料中添加重组抗菌肽对吉富罗非鱼生长性能及免疫力的影响

Effects of recombinant antimicrobial peptides on growth and immu-nity in tilapia(GIFT)

以吉富罗非鱼(genetically improved farmed tilapia,GIFT)幼鱼(体质量10.68 g±0.53 g)为研究对象,在实验饲料中分别添加0、5、10、20、50 mg/kg重组中国明对虾抗菌肽以及100 mg/kg氟苯尼考,并于实验结束时进行注射攻毒(嗜水气单胞菌)。通过8周的养殖实验,研究了饲料中添加抗菌肽对吉富罗非鱼幼鱼的生长性能、免疫指标以及攻毒实验的影响。结果显示,饲料中添加5～10 mg/kg抗菌肽可以显著提高罗非鱼的增重率、红细胞总数以及过氧化氢酶的活性,当添加量为5 mg/kg时,特定生长率最高;当添加量为50 mg/kg时,肝脏的超氧化物歧化酶与血清中溶菌酶活性较对照组显著降低(P<0.05);添加100 mg/kg氟苯尼考组较对照组能显著提高红细胞总数;当添加量为5～20 mg/kg时,嗜水气单胞菌攻毒后的死亡率显著降低(P<0.05),以5 mg/kg组存活率最高,氟苯尼考组差异不显著。结论认为,饲料中添加适量重组抗菌肽对幼鱼有一定的促生长作用,并能提高部分免疫指标以及攻毒后的存活率,但过高剂量的抗菌肽对幼鱼的生长与部分酶指标有一定的负面影响,因此建议抗菌肽的添加量不超过20 mg/kg。本研究旨为对虾抗菌肽在罗非鱼饲料中的合理应用提供实验依据。

Antimicrobial peptides have attracted considerable attention because of their potential use for therapy and prophylaxis. We evaluated the effects of dietary supplementation with recombinant antimicrobial peptide on growth, immunity, and performance in the protest test in tilapia （genetically improved farmed tilapia, GIFT） （initial body weight 10.68g±0.53g）. The fish were divided into six treatment groups and fed experimental diets containing 0, 5, 10, 20, or 50 mg/kg recombinant antimicrobial peptide （RAP） derived from Fenneropenaeus chinensis or 100 mg/kg florfenicol for 56 d. Weight gain, red blood cell numbers, and catalase activity were significantly higher in the groups supplemented with 5 and 10 mg/kg compared with the control. The specific growth rate was highest in the group given 5 mg/kg RAP. Liver superoxide dismutase activity and serum lysozyme activity were significantly lower in the group given 50 mg/kg RAP than in the control. Supplementation with 100 mg/kg florfenicol increased the number of red blood cells, but had no effect on the other indexes. Following infection with Aeromonas hydrophila, the death rate was significantly lower in groups fed between 5–20 mg/kg RAP than in the control. The survival was highest in the group fed 5 mg/kg. Our results suggest that dietary supplementation with appropriate levels of antimicrobial peptide improves growth, immunity, and performance in the protest test in tilapia. However, increasing the dose can lead to negative effects on growth and enzyme activity. Therefore, we recommend that supplementation should not exceed 20 mg/kg. Our results provide insight into the proper application of recombinant antimicrobial peptides to tilapia.