从发病的养殖水样及鳗鲡体表溃烂处组织分离出一株M-1菌株,经16S r RNA测序鉴定为嗜水气单胞菌。对该菌进行溶血性、药物敏感性试验,结果表明:该菌株具有溶血性,并对链霉素、庆大霉素表现敏感,而对四环素、青霉素G、左氟沙星、诺氟沙星等6种抗生素表现出耐药性。在鳗鲡感染试验中,表现出具有较强的致病性,注射约107CFU/mL病原菌液0.5 mL,72 h内致死率达100%。在养殖防治模拟试验中,20%戊二醛溶液和10%聚维酮碘溶液的防治效果与庆大霉素接近,可大幅度杀灭水体中的嗜水气单胞菌,从而降低鳗鲡死亡率。从健康、绿色养殖长远角度来看,建议采用20%戊二醛溶液、10%聚维酮碘溶液不易导致增强耐药性的杀菌药物。
To obtain higher economic benefits,large eel breeding companies classify live eels by weight.Due to their strong mobility and smooth body surface,living eels are not suitable for traditional mechanical weight measurement.In this study,a live eel sorting machine based on machine vision was developed,and a novel method was developed for obtaining live eel weight measurements through images.First,a backlit workbench was designed to capture static images of eels,and then the projection area and skeleton length of the images were obtained by image preprocessing.For the eel's body shape,which is generally cylindrical and gradually transitions to a flat tail,the tail posture changes affect the shape of the images;thus,a weight measurement model combining the projected area and the skeleton length was proposed.The optimal scale division coefficient of the weight model was found to be 0.745 by experimentation.Then,select eels of different weight ranges were used for model error verification and to obtain the correction function of the error.The weight gradient was used to confirm the corrected eel weight model.Finally,the system calculation results were compared with the actual measurement results.The root mean square error(RMSE)was 12.94 g,and the mean absolute percentage error(MAPE)was 2.12%.The results show that the proposed method provided a convenient,fast,and low-cost non-contact weight measurement method for live eels,reduced the damage rate of live eels,and can meet the technical requirements of actual production.
The swamp eel(Monopterus albus)is a commonly cultured freshwater fish.Selection and cultivation of fecund broodstock is crucial for efficient artificial reproduction in this species.However,there are currently no guidelines for selecting high-quality males in M.albus.This study quantitatively investigated the sperm motility of male swamp eels during the breeding season by using computer-assisted sperm analysis system.Variability in the proportion and number of motile sperm was observed between individual males.The testes were grouped into high-quality and low-quality according to sperm quality.Morphometric parameters of the two groups were analyzed.We found that high-quality testes were longer(150±27 mm verses 127±19 mm)than low-quality testes.Besides,the proportion of testes with a dark appearance was slightly higher(58.3%verses 48.1%)in the high-quality group than in the low-quality group.Metabolomic analysis was conducted to compare the metabolite profiles of high-quality and low-quality testes.Glycerophospholipids,organic acids,glycerolipids,amino acids,sphingolipids,and nucleotides were the most abundant metabolites in the testes of swamp eels.Moreover,135 differential metabolites were identified.Several nucleotide derivatives,including 50-deoxyadenosine,20-deoxyadenosine,and ribosyl adenosine,were the most significantly enriched metabolites in highquality testes.These metabolites are potential indicators for the testis quality in M.albus.Altogether,our work provides systematic and quantitative data about the physiological and biochemical characteristics of M.albus testis,which provides an evidential basis for the selection of high-fecundity parents to improve artificial reproduction efficiency of M.albus.
Fei LiuXing LinKaifeng MengYuanyuan ChenHairong LiuYuanli ZhaoDaji Luo