涌泉根灌不同浓度肥液入渗特性及土壤湿润体模型研究

为了研究涌泉根灌肥液入渗特性及湿润体水氮运移的变化规律,在陕北米脂山地微灌枣树示范基地原状土上进行了涌泉根灌肥液入渗试验。结果表明:累积入渗量与入渗时间之间符合Kostiakov幂函数关系(R20.9,P0.01);涌泉根灌入渗能力与增渗效果均随肥液浓度增大而增大;水平湿润锋与竖直湿润锋运移距离均随肥液浓度增大而增大,且均与入渗时间呈显著的幂函数关系,水平方向和竖直方向的湿润锋运移距离的拟合值与实测值的相对误差在–3.84%～5.20%以内。肥液浓度的不同对于湿润体大小略有影响。提出了涌泉根灌肥液入渗湿润体内土壤含水率和NH_4~+-N浓度分布的数学模型,即在一定浓度范围内,单位含水率的变化可引起的肥液浓度变化,且模型的计算精度较高(模拟值与实测值相对误差在10%以内),并符合湿润体内土壤含水率和NH_4~+-N分布规律,可对不同位置处土壤含水率及NH_4~+-N含量进行估算。水分分布情况对肥液浓度条件敏感性较低,NH_4~+-N分布情况对肥液浓度条件敏感性较高。研究可为涌泉根灌水肥高效利用提供参考。     

Fishmeal replacement by soybean,rapeseed and cottonseed meals in hybrid sturgeon Acipenser baerii ♀ × Acipenser schrenckii ♂

A 12‐week feeding trial was conducted to evaluate the effects of replacing fishmeal (FM) with soybean meal (SBM), rapeseed meal (RM) and cottonseed meal (CSM) on growth, feed utilization and body composition of juvenile hybrid sturgeon Acipenser baerii ♀ × Acipenser schrenckii ♂ (initial body weight, 8.63 ± 0.24 g). Five isonitrogenous and isoenergetic diets were formulated as follows: a control diet (FM60) containing 600 g/kg FM and four other diets (FM45, FM30, FM15 and FM0 containing 450, 300, 150 and 0 g/kg FM, respectively) where protein from FM was substituted by a mixture of SBM, RM and CSM. Fish fed FM0 and FM15 had poorer growth performance, feed utilization, apparent digestibility coefficients of dry matter, protein, lipid and gross energy, and fed FM0 had poorer hepatosomatic index and survival compared with the fish fed FM60. The whole body lipid in fish fed FM0 was significantly higher than that in fish fed FM60 and FM15. This study indicates that 300 g/kg of FM can be replaced with a mixture of SBM, RM and CSM in the diet of juvenile hybrid sturgeon without compromising growth performance, feed utilization and body composition.     

Effects of dietary protein levels on the activity of the digestive enzyme of albino and normal Apostichopus japonicus (Selenka)

We evaluated the effects of different proportions of dietary protein (5%, 10%, 15%, 20%, 25% and 30% protein) on the activity of digestive enzymes of normal and albino Apostichopus japonicus. The experimental diets were fed for 60 days, the optimal conditions for digestive enzyme activity in sea cucumbers were studied. The optimal temperature for protease was 29.3°C and the optimal pH was 1.8. The optimal temperature for amylase was 34.3°C and the optimal pH was 6.7. The optimal temperature for cellulase was 56°C and the optimal pH was 5.9. The activity of intestinal protease increased at first and then decreased as the proportion of dietary protein increased, reaching the maximum when the proportion of protein was 19.7%. The activity of protease in the intestine of normal sea cucumber was significantly lower than that of albino sea cucumber, and the activity of amylase was significantly higher than that of albino sea cucumber. This study is expected to provide a basis for further explaining the ecological difference of albino and normal A. japonicus.     

哈维氏弧菌RT-LAMP检测方法建立与应用

哈维氏弧菌(Vibrio harveyi)是引起海南省后水湾深水网箱养殖卵形鲳鲹(Trachinotus ovatus)"烂身病"的主要病原菌。为了能够快速诊断该病原菌,急需建立一种耗时短、准确以及便捷的检测方法。本研究利用分离到的致病菌株QT520的ToxR基因序列设计特异性引物和加入SYTO-9特异荧光染料,建立了一种可以实时、快速检测哈维氏弧菌的LAMP法(RT-LAMP)。该方法对哈维氏弧菌的基因组DNA及菌液灵敏度分别为100 fg/μL和10~3 cfu/mL,与Real-time PCR法检测灵敏度相当,比普通PCR的检测灵敏度要分别高1000倍和10倍,能有效区分哈维氏弧菌与坎氏弧菌(Vibrio campbellii);可以实时观察检测结果,且检测时间只需要40 min;具有耗时短、特异性和灵敏度高、仪器便携、操作简单且能实时观察检测结果等优点,非常适合在生产现场进行哈维氏弧菌的检测。     

First record of infection by Trypanosoma sp. of Colossoma macropomum (Serrasalmidae), a neotropical fish cultivated in the Brazilian Amazon

Fish farming has grown rapidly in Brazil over the last two decades, due in part to the availability of water and species with potential for cultivation, such as Colossoma macropomum. This farmed fish, however, can be affected by parasitic infections with high mortality rates (>35%). The main objective of the present study was to describe the first occurrence of the Trypanosoma species in Colossoma macropomum, which occurred in fish cultured in the Brazilian Amazon region, as well as to morphologically characterize the trypomastigotes and the impact of these hemoparasites on the body condition of the hosts. The trypanosomes found in the blood of Colossoma macropomum were morphologically characterized by the size of the trypomastigote form, indicating the presence of only one morphotype. Of the 39 hosts examined from one fish farming, 41.0% were infected by Trypanosoma sp., with low levels of infection (mean blood density of 3.7/μL). The condition factor of the asymptomatic hosts was not affected by hemoparasitism. There was no correlation between the abundance of Trypanosoma sp. and the condition factor and size of the hosts. Finally, our understanding of host-parasite interactions and the detection of emerging diseases are fundamental for aquaculture.     

Effects of Dietary Digestible Protein and Energy Levels on Growth Performance,Feed Utilization,and Body Composition of Juvenile Permit,Trachinotus falcatus (Linnaeus, 1758)

A 9‐wk study was conducted to evaluate the effect of dietary protein and energy on growth performance of juvenile permit, Trachinotus falcatus, growing from approximately 30 to 150 g. Nine experimental diets were formulated to contain three levels of crude protein (400, 450, and 500 g/kg dry matter [DM]); and three levels of crude lipid (100, 200, and 300 g/kg DM) in a 3 × 3 factorial design. Growth rate and feed efficiency were significantly improved with increasing dietary protein levels from 400 to 500 g/kg and with dietary lipid levels from 100 to 200 g/kg. Fish body protein content was positively correlated with dietary ratio of digestible protein (DP) to digestible energy (DE) (P < 0.01, R² = 0.83), while body lipid was negatively correlated with dietary DP/DE (R² = 0.55, P < 0.05) but positively correlated with dietary DE levels (R² = 0.66, P < 0.01). Results showed a protein‐sparing effect, as protein retention was significantly increased by increasing dietary lipid level. In conclusion, the diet containing DP of 392.7 g/kg and DE of 18.8 MJ/kg (DM), corresponding to a DP/DE of 20.9 g/MJ, is suggested as an optimal feed for growth and feed efficiency in juvenile permit.     

基于体压分布的床垫硬度对人体舒适性的影响

床垫作为睡眠的平台，其支撑性能对人体健康和睡眠舒适性有着重要的影响。在定量化研究床垫软硬度的基础上，利用体压分布测试，通过软硬度适宜的床垫与硬度较大的床垫进行对比分析，研究床垫软硬度对人体舒适性的影响。结果表明：(1)软硬度适宜的床垫有利于人-床界面压力的分散性，有利于人体腰部支撑；(2)适宜于男性受试者的床垫的软硬度小于适宜于女性受试者的床垫软硬度。     

年龄、温度、膘情对伊犁马卵泡发育的影响

【目的】 研究新疆昭苏地区伊犁马发情周期内卵泡发育变化规律,分析年龄、温度、膘情对伊犁马母马卵泡发育的影响,为掌握伊犁马母马卵泡发育规律提供理论依据。【方法】 选取伊犁哈萨克自治州昭苏县康苏马业配种站内,同一草场放牧情况下84匹母马作为研究对象监测发情期内卵泡发育,分析对比不同年龄、温度、膘情对伊犁马卵泡发育时长的差异性。【结果】 年龄Ⅱ组TF3-F5显著高于年龄Ⅲ组(P＜0.05)。年龄Ⅱ组TF4-5显著高于年龄Ⅲ组(P＜0.05)。平均高温对TF1-F2具有显著影响(P＜0.05),平均高温Ⅰ组TF1-F2显著高于平均高温Ⅱ组(P＜0.05)。平均低温对TF1-F2具有极显著影响(P＜0.01),平均低温Ⅰ组TF1-F2极显著高于平均低温Ⅱ组(P＜0.01)。积温对TF1-F2具有显著影响(P＜0.05),积温Ⅱ组TF1-F2极显著高于积温Ⅰ组(P＜0.01)。膘情对TF1-F2、TF3-F4、TF1-F5、TF2-F5、TF3-F5均具有极显著影响(P＜0.01),对TF2-F3具有显著影响(P＜0.05)。膘情Ⅰ组TF1-F2极显著高于膘情Ⅲ组(P＜0.01)。膘情Ⅰ组TF2-F3显著高于膘情Ⅲ组(P＜0.05)。膘情Ⅲ组TF3-F4极显著低于膘情Ⅰ组(P＜0.01),膘情Ⅲ组TF3-F4显著低于膘情Ⅰ组、膘情Ⅱ组(P＜0.05)。膘情Ⅰ组TF1-F5极显著高于膘情Ⅱ组、膘情Ⅲ组(P＜0.01),膘情Ⅱ组TF1-F5显著高于膘情Ⅲ组(P＜0.05)。膘情Ⅰ组TF2-F5极显著高于第Ⅲ组(P＜0.01),膘情Ⅰ组TF2-F5显著高于膘情Ⅱ组、膘情Ⅲ组(P＜0.05)。【结论】 年龄、温度、膘情均一定程度的影响伊犁马母马的卵泡发育,其中膘情对卵泡发育有极显著影响,体况较差可抑制母马卵泡发育。     

透气隔水埋体对土壤水分入渗与溶质运移的影响

为分析透气隔水(弱透水)埋体促进水分入渗与溶质运移功效,开展了不同容重(1.40,1.45,1.50,1.60 g/cm~3)透气隔水(弱透水)埋体的一维垂直土柱入渗试验,分析了不同容重的透气隔水(弱透水)埋体对土壤水分入渗与溶质分布的影响。结果表明,透气隔水(弱透水)埋体能够增加土壤累积入渗量,推动湿润锋运移,在一定范围内,随着透气隔水(弱透水)埋体容重增加,湿润锋推进速度与土壤入渗率均增加。600 min时,土壤累积入渗量相对增加7.42%～29.17%,湿润锋深度达到27 cm,入渗时间相对减少26.97%～64.27%。相比于对照组,不同容重的透气隔水(弱透水)埋体均能降低溶质向深层土壤迁移数量。Philip模型和代数模型均能描述透气隔水(弱透水)埋体土壤水分入渗过程,且Philip模型中吸渗率S和代数模型中综合形状系数α均与透气隔水(弱透水)埋体内外容重比呈正相关关系。研究结果表明透气隔水(弱透水)埋体能够通过改变上层土壤吸力分布提高水分入渗能力与溶质传输效率,实现对城市雨水径流调控和净化。     

南京地区斑点叉尾鮰养殖池塘水体微生物群落结构研究

微生物群落在水产养殖中起着重要作用,深入了解微生物群落组成及其构建机制对了解池塘生态功能具有重要意义。本研究采用高通量测序技术对南京地区斑点叉尾鮰(Ictalurus punctatus)养殖池塘水体中细菌群落结构特征进行了分析。结果显示,斑点叉尾鮰养殖池塘水体细菌群落结构呈现出明显的季节性变化,整个年度水体细菌群落呈现出连续的演替特征,冬季与春季、夏季与秋季的细菌群落结构较为相似。优势菌群主要为蓝藻门(Cyanobacteria)、放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)。环境因子中,总溶解性悬浮物(TDS)、水温(Temp)、酸碱度(pH)、亚硝酸盐(NO_2~--N)和总有机碳(TOC)与斑点叉尾鮰养殖池塘水体细菌群落结构有显著相关(P0.05),对细菌群落结构的塑造影响也最大(r~20.6)。