饲料中添加甘草酸对刺参生长、免疫及抗病力的影响

以初始体重为(6.80±0.00)g左右的刺参(Apostichopus japonicus Selenka)为研究对象,在室内循环水系统中进行8周饲喂实验,研究饲料中添加不同梯度的甘草酸对刺参生长、免疫及其抗病力的影响。以基础饲料为对照组,在基础饲料中分别添加50、100和200mg/kg的甘草酸,共配制4种实验饲料。结果表明:饲料中添加甘草酸对刺参的成活率没有影响,各处理组均为100%。饲料中添加200mg/kg甘草酸可显著提高刺参的特定生长率(SGR)(P0.05)。养殖实验结束后,通过注射刺参腐皮综合症致病菌灿烂弧菌(Vibriosplendidus)进行刺参攻毒实验,攻毒后14d内对照组与50mg/kg添加组的累计发病率(分别为38.3%和36.7%)显著高于100和200mg/kg添加组(分别为30.0%和26.7%)(P<0.05)。实验可得到以下结论:(1)饲料中添加200mg/kg甘草酸可以提高刺参养殖的产量,同时可以提高刺参的非特异性免疫力和抗病力;(2)在研究中,全周期养殖期间投喂甘草酸不会产生免疫疲劳或其他副作用。  

EFFECTS OF DIETARY GLYCYRRHIZIN ON GROWTH,IMMUNITY OF SEA CUCUMBER AND ITS RESISTANCE AGAINST VIBRIO SPLENDIDUS

A 8-week feeding experiment was conducted to evaluate the effects of glycyrrhizin on the growth,non-specific immunity of sea cucumber (Apostichopus japonicus Selenka) as well as its resistance against Vibrio splendidus.The fish meal and defatted soybean meal were used as main protein source and fish oil and lecithin as main lipid source.The basal diet (19.6% crude protein and 4.7% crude lipid) was used as control.Four practical diets were formulated containing four glycyrrhizin levels: 0,50,100 and 200 mg/kg feed,respectively.Each diet was randomly allocated to triplicate groups of sea cucumber in indoor 200-L fiberglass tanks with circulating seawater and constant aeration.And each tank was stocked with 30 sea cucumbers initial average weight (6.80±0.00) g.The water temperature was (17 ± 0.5)℃and the salinity was (25±1)‰ during the experimental period.At the termination of the feeding experiment,6 sea cucumber of each replicate were dissected and the coelomic fluid was collected with the 1︰1 ratio of the anticoagulant solution and coelomic fluid volumes.For the measurement of immune parameters,cells were counted immediately after sampling using a hemocytometer and then rapidly adjusted to 2 × 106 cells/mL with isotonic buffer.The results showed that glycyrrhizin supplemented at 200 mg/kg significantly enhanced the specific growth rate of sea cucumber (P0.05).During the feeding trial,no death of sea cucumber was observed among diet treatments.Sea cucumbers fed diet with 200 mg/kg glycyrrhizin had significant higher activi-ties of nitric oxide synthase (NOS) and lysozyme (LZM) than those fed other diets (P0.05).After 56 days of feeding with glycyrrhizin-diets or control diet,20 sea cucumber of each replicate (each dietary treatment has 60 sea cucumber) were injected into the body wall with the 1×109 cfu/mL live V.splendidus bacterial stock solution at a dose of 0.1mL per sea cucumber (based on the data of 10-day LD50 pre-test).The sea cucumber that fed the control diet were injected with saline (0.1 mL) served as the unchallenged control.The results showed that sea cucumbers fed the diet either with 100 or 200 mg/kg glycyrrhizin had significantly lower accumulative morbidity compared with the control and 50 mg/kg glycyrrhizin groups (P0.05).According to these results,some conclusions are put forward as follows: (1) the oral administration of glycyrrhizin to A.japonicus Selenka at a dose of 200 mg/kg improves growth,enhances the immunity as well as increases disease resistance;(2)long-duration administration of glycyrrhizin is sufficiently safe for sea cucumber farming."