裸难地适生牧草引种试验初报

引种内蒙白花草木樨进行绿化和词草试验表明,内蒙白花草木樨有较强的适应性,耐干旱瘠薄,并具有蓄水保土能力,根系固氮能力强、改良土壤效果佳,同时草木樨蛋白质含量高,营养成分丰富,是较好的饲料。白花草木樨播种简便、病虫害少,是裸难地极好的绿化先锋草种和优质饲草。     

Evaluation of potential of lupin meal as an alternative to fish meal in juvenile Penaeus monodon diets

An indoor feeding trial in a flow-through marine water system was performed to evaluate the feasibility of using dehulled lupin Lupinus albus seed meal as a protein source to replace fish meal in diets for the juvenile Penaeus monodon. Five isonitrogenous (40% crude protein) diets formulated by replacing 0, 25, 50, 75, and 100% of fish meal protein by lupin meal protein were fed to shrimp (mean initial weight of 4.32 ± 0.23 g) three times daily at a feeding allowance of 5% body weight per day for 42 days. Shrimp fed diets with 0, 25, 50 and 75% replacement had similar (P > 0.05) weight gain, dry matter feed intake, feed conversion ratio (FCR), protein efficiency ratio (PER), and apparent net protein utilization (ANPU). Shrimp fed the highest dietary inclusion level of lupin meal (100% replacement) had significantly (P < 0.05) lower responses for all the above parameters than shrimp fed all other diets. Survival was high (87–100%) and similar for all diets. Apparent dry matter digestibility (ADMD) of diets with 25, 50, 75 and 100% replacement of fish meal with lupin meal was similar (75.6–76.6%) and significantly (P < 0.05) higher than that of diet with 0% replacement (73.9%). Diets containing the two highest lupin inclusion levels (75 and 100% replacement) had significantly (P < 0.05) better apparent protein digestibility (APD) than those containing the two lowest lupin meal inclusion levels (0 and 25% replacement). There were no significant differences (P > 0.05) in whole-body composition (dry matter, protein, lipid and ash) of shrimp fed on the various diets. Pellet water stability was inversely related to level of lupin meal inclusion. It was found, in this study, that up to 75% protein of fish meal can be replaced with the protein of dehulled lupin seed meal in diets for juvenile P. monodon. The diet with total replacement of fish meal containing 40% lupin meal was utilized very poorly by the shrimp.     

Effects of low dietary protein level on serum oestradiol,testosterone and sex reversal in rice field eel,Monopterus albus (Zuiew)

We investigated the effects of low dietary protein in isocaloric diets on sex reversal of Monopterus albus by evaluating the oestradiol (E₂) and testosterone (T) concentrations, gonadosomatic index (GSI), sex ratio and gonad structure at the histological level. Fish (9.50 ± 1.50 g average initial weight; n=3 per group) were fed with five practical diets containing 100, 150, 200, 250 or 400 g kg^?1 crude protein to apparent satiation for 15 months. Serum E₂ and T concentrations were determined by radioimmunoassays. E₂ concentrations and GSI significantly increased while T concentrations decreased as the dietary protein level was raised. Fish fed 400 g kg^?1 of dietary protein had significantly higher E₂ concentrations and GSI than those fed with lower dietary protein levels. The T concentrations of fish fed 100 g kg^?1 of dietary protein was significantly higher than that of fish fed higher dietary protein levels. The shift of sex ratio towards more male and intersex fish was observed with decreasing dietary protein levels. Therefore, low dietary protein level may promote sex change from female to male in M. albus. This study provides important information for successful reproductive management and may be exploited for aquaculture of this species.     

投喂水平对黄鳝(Monopterus albus)生长、肠道消化酶活性及部分血清生理生化指标的影响

为探究不同投喂水平对黄鳝(Monopterus albus)生长、肠道消化酶活性及血清生理生化指标的影响,分别以初始体重为(68.85±0.44)g和(26.67±0.17)g的2种规格黄鳝为研究对象,大规格按照体重的2.8％、3.6％、4.4％和5.2％投喂;小规格按照体重的3.0％、4.0％、5.0％、6.0％和7.0％投喂;每个处理组设置3个重复,大规格组50尾/箱,小规格组100尾/箱,实验持续56d.实验结果显示,随着投喂水平的增加,2种规格黄鳝增重率、饲料系数、肝体比以及全鱼脂肪含量都显著升高(P＜0.05),但金鱼蛋白含量呈下降趋势.大规格黄鳝在投喂水平为4.4％和5.2％时增重率达到最高水平,且组间差异不显著(P＞0.05);大规格黄鳝肠道脂肪酶和胰蛋白酶活性随投喂水平的增加而显著升高(P＜0.05);大规格黄鳝血清超氧化物歧化酶(SOD)活性、总胆固醇(TC)含量先升后降,血清甘油三脂(TG)含量呈上升趋势;大规格黄鳝在投喂水平为4.4％时,SOD和溶菌酶(LZM)活性达到组间较高水平.随着投喂水平的增加,小规格黄鳝肠道胰蛋白酶活性显著升高(P＜0.05);血清TG、TC含量升高,SOD活性降低,血糖含量呈先升后降趋势.在投喂水平为6％时,小规格黄鳝的SOD和LZM活性均处在较高水平.本研究表明,当大规格黄鳝投喂水平为4.4％、小规格黄鳝投喂水平为5％-6％时,黄鳝的生长性能达到较佳状态.     

不同来源黄鳝(Monopterus albus)繁殖力的比较分析

比较不同来源黄鳝(Monopterus albus)的个体繁殖力,研究了其个体繁殖力分布特征、变化规律及与生物学指标的关系.以怀卵量作为绝对繁殖力的表征参数,对雌性黄鳝进行解剖测定.结果显示,野生黄鳝绝对繁殖力(F)为181-729粒,人工培养黄鳝F值为165-589粒,人工繁育黄鳝F值为135-352粒;野生黄鳝基于体重的相对繁殖力(FW)为5.4-11.8粒/g,人工培养黄鳝FW为3.5-9.3粒/g,人工繁育黄鳝FW为4.96-8.55粒/g;野生黄鳝基于体长的相对繁殖力(FL)为5.8-17.2粒/mm,人工培养黄鳝FL为4.85-15.00粒/mm,人工繁育黄鳝FL为4.35-9.03粒/mm,不同来源黄鳝在F、FL、FW上均有极显著差异(P＜0.01).来源和体色均不同的黄鳝其F和FL均具有极显著差异,而FW差异不显著;所有黄鳝的F和野生黄鳝的FL与体长、体重生物学指标密切相关,其余F、FL和FW与各生物学指标均相关性较小.研究表明,野生黄鳝的F、FL和FW均高于人工培养和人工繁育的黄鳝,怀卵量优势明显.     

Aeromonas veronii caused disease and pathological changes in Asian swamp eel Monopterus albus

More and more diseases were occurred in the aquaculture of Asian swamp eel. Bacterial isolates were collected from the pathogenic organs of diseased Asian swamp eels. A dominant strain, Aeromonas veronii JL‐01, was isolated and identified from the liver and intestine tissue of diseased Asian swamp eels. The symptoms of fish infected artificially with A. veronii were the same as those observed under natural infection. The mortality rate was 40%–80% and infected Asian swamp eels died 2–3 days after infection. Drug sensitivity tests showed that the isolated bacterium was highly sensitive to seven kinds of antibiotics, including cephalosporins, aminoglycoside, quinolones, tetracyclines (except Tetracycline), pheniclos, nitrofurans and sulfonamides. The bacterium was resistant to penicillins (except Piperacillin), macrolides, polypeptides and lincomycin. The histological changes in Asian Swamp Eel induced by A. veronii infection mainly occurred in the liver, intestines and kidney. A. veronii showed strong pathogenicity towards the Asian swamp eel, causing tissue damage and death. Gentamycin, doxycycline and sulfamethoxazole could be used for preventing and treat this disease.     

黄鳝生长差异基因发掘及其调控机制初步研究

为揭示黄鳝(Monopterus albus)生长相关基因的调控机制,对相同亲本具有显著性生长差异的黄鳝肝脏进行了转录组测序分析。结果显示,转录组测序共得到19149个基因,其中差异基因598个,差异基因中有303个基因显著上调,295个显著下调。KEGG通路分析发现,598个差异基因分属262条通路中,其中有38条通路显著富集。GO功能注释发现,与生长相关的差异基因有7个,分别为col1α1、nkx6.1、nnos、plexina4、igfbp1、pcgf1和h3.3,这些基因表达水平的变化可能对黄鳝神经、内分泌和消化系统的发育及生理活动产生了调节作用从而影响了黄鳝的生长。结合KEGG通路分析发现,col1α1所在的利什曼病通路和nnos所在的精氨酸和脯氨酸代谢通路富集显著,说明其对黄鳝生长具有重要调节作用。     

嗜水气单胞菌源黄鳝出血病的组织病理学研究

应用组织学方法研究了分离自患出血病黄鳝(Monopterus albus)体内的嗜水气单胞菌(Aermonas hydrophila)人工感染健康黄鳝后引起的组织病理学变化。结果显示:健康黄鳝感染嗜水气单胞菌后发病呈急性过程,感染后15~33 h为发病死亡高峰期。黄鳝人工感染后出现的临床症状与自然发病病例相似,主要表现:体表出现出血斑、肛门红肿、腹腔充血以及各实质性器官出血、充血。人工感染黄鳝的肝脏、脾脏和肾脏的病理变化明显:肝脏出现广泛的充血、出血,肝细胞出现空泡变性、坏死;肾脏肾小管上皮的肿胀、结构的消失,肾小球出血、变性坏死;脾脏充血、出血;肠粘膜上皮脱落,基底膜排列紊乱,大量出血。结果表明,嗜水气单胞菌感染黄鳝后的病理变化主要表现为肝脏、肾脏等实质性器官充血、出血,及广泛的组织细胞变性和坏死。     

黄鳝微卫星引物筛选及其在保护遗传学上的应用

研究了远缘种鲤的微卫星引物对黄鳝的适用性。结果显示,31对鲤微卫星引物中有11对引物能对黄鳝DNA模饭扩增出特异性带谱。每对引物扩增的等位基因数在3～13个,平均每个位点有5．6个等位基因,显示了较高的多态性。其中引物P1最理想,其PCR扩增产物能区分来自湖南、广东和孟加拉3个不同地域的黄鳝种群。应用微卫星技术对3个不同地域的黄鳝基因组DNA多态性分析结果显示,湖南、广东和孟加拉黄鳝群体内平均相似率依次为95．5％,95.8％和93．5％,平均变异度依次为0．045,0．042,0．063。群体间的相似率及变异度分析显示：湖南黄鳝和广东黄鳝群体间平均相似率为91．0％,变异度为0．045;湖南黄鳝和孟加拉黄鳝群体间平均相似率和变异度分别为55．7％和0．443;广东黄鳝和孟加拉黄鳝群体间平均相似率和变异度分别为58．6％和0．414。综合微卫星分析结果、黄鳝的外形特征及地理位置,可以推测,广东黄鳝与湖南黄鳝为同一个生物种的不同地理种群,而孟加拉黄鳝为同属中另一个种。     

白色链霉菌Ys6-101产盐霉素的发酵条件优化

盐霉素作为药物饲料添加剂在养禽业得到广泛应用和普及,但由于其主要生产来源存在耗油量大且成本高的难题,盐霉素的工业化生产受到较大阻碍。为优化盐霉素发酵过程工艺,提高盐霉素工业得率,本文基于实验室筛选菌株—白色链霉菌Ys6-101,通过改变一级种子液和二级种子液的消后pH和接种量,对盐霉素种子培养条件进行了探究和优化。结果表明,种子消后pH6.80和接种量18%分别为白色链霉菌种子培养阶段的最适pH和接种量,且发酵工艺条件优化后,即一级种子消后pH6.80,接种量20 mL/110 L,二级种子消后pH6.80,接种量18%,发酵液中盐霉素效价提高了12.5%。因此,选择合适的接种量和消后pH不仅可以发挥发酵罐的最大效率,还有利于缩短发酵周期,提高发酵效价,降低生产成本。