五倍子预防草鱼细菌性烂鳃病效果的研究

五倍子能预防鱼类烂鳃病,但作用剂量不明确。为探明五倍子的推荐使用剂量,该研究从体内、体外两方面考查了不同剂量五倍子对病原菌抑制效果和饲料中添加不同剂量五倍子对草鱼烂鳃病预防效果的影响。将五倍子煎液以40、60、80、100 mg/kg剂量加入Shieh琼脂选择培养基,涂布柱状黄杆菌,培养72 h并计数,计算抑菌率;选择健康的草鱼幼鱼240尾,分为4个组,对照组饲喂基础饲料,3个试验组分别添加1%、2%、4%五倍子进行投喂,用柱状黄杆菌悬液向鱼缸连续泼洒3 d攻毒,饲养56 d后测定血清、肠、肝胰脏溶菌酶活力及血清补体C3、IgM含量。结果表明,80~100 mg/kg的五倍子抑菌效果明显,100 mg/kg能完全抑菌;2%五倍子剂量组肝胰脏溶菌酶活力显著（P<0.05）高于对照组,因此,五倍子在草鱼饲料中推荐添加剂量为2%。

Preventive Effect of Galla chinensis on Bacterial Gill-rot Disease of Grass Carp

Galla chinensis can prevent fish gill-rot disease, but the using dosage is not clear. In order to ascertain the recommended dosage of Galla chinensis, this study examined the inhibitory effect of different doses of Galla chinensis on pathogentic bacteria and the effect of dietary supplementation of different doses of Galla chinensis on the preventive effect of grass carp gill-rot disease in vivo and in vitro. The Galla chinensis decoctions were added to Shieh agar selection medium at doses of 40, 60, 80, 100 mg/kg, coated with Flavobacterium columnare, cultured for 72 h and counted to calculate the inhibition rate; a total of 240 healthy grass carp juveniles were selected and divided into 4 groups, the control group was fed with basal diet, and the 3 test groups were fed with the basal diet adding 1%, 2%, and 4% Galla chinensis respectively, and the suspension of Flavobacterium columnare was sprayed into the fish tank for 3 consecutive days to challenge. After 56 days, the activity of lysozyme in serum, intestine and hepatopancreas, and the serum contents of complement C3 and IgM were measured. The results showed that Galla chinensis at 80~100 mg/kg had obvious antibacterial effect, and Galla chinensis at 100 mg/kg could completely inhibit the bacteria; the 2% Galla chinensis group had significantly （P<0.05） higher hepatopancreas lysozyme activity compared with that of the control group. Therefore, the recommended dosage of Galla chinensis in grass carp feed is 2%.