维生素E对蛋鸡产蛋后期产蛋性能和蛋品质的影响

文章旨在研究日粮中不同梯度维生素E添加水平对蛋鸡产蛋后期产蛋性能和蛋品质的影响.试验选择60周龄罗曼白壳商品蛋鸡300羽,试验随机分为5组,添加水平分别为0(对照组),30、60、120、240 mg/kg,每组6个重复,每个重复10羽鸡,预试期1周,正试期8周.结果表明:与对照组相比,蛋鸡产蛋后期日粮中添加120 m...     

宁夏南部山区不同土地类型土壤养分的分布特征研究

通过对宁夏南部山区阳洼流域不同土地类型下土壤养分分布特征进行研究,结果表明:流域土壤养分整体上表现为草地>农地>梯田>林地>沟道.流域各类型下土壤养分随土层深度增加,有逐渐下降的趋势.在α=0.05下,不同土层间土壤速效磷、速效钾、全磷存在显著差异.在不同土地类型下土壤全磷受母质影响,变异系数仅为21.41%,在土壤中以稳定态存在,而流域有效磷的变异系数可达178.56%,土壤有效磷含量的空间分布较为复杂,易受随机因素影响.草地利用类型下土壤有机质、碱解氮的变异系数为35.24%,29.04%,远高于林地利用类型.pH值与速效磷、全氮、有机质和碱解氮都有极显著的相关关系,有机质和碱解氮、全氮相关性较高,相关系数(R)分别为0.914**,0.839**,而全磷与有效磷之间没有表现出明显相关关系.     

响应面法优化猪粪和玉米秸秆混合厌氧发酵产沼气工艺

利用中心组合设计试验考察粪秸比、发酵温度和发酵底物浓度3个因素对猪粪和玉米秸秆混合厌氧发酵产沼气的影响,运用响应面法对其工艺参数进行优化.研究结果表明,根据试验数据建立的二次多项式数学模型具有高度显著性(P ＜0.0001),相关系数R2=0.9866,说明预测值和试验值之间具有很好的拟合度.通过对二次回归数学模型解逆矩阵得到粪秸混合厌氧发酵产沼气的最优化条件为:粪秸比(玉米秸秆干物质占发酵原料干物质的质量分数)为30％,发酵温度为35℃和发酵底物浓度为12.74％.在此条件下,粪秸混合厌氧发酵的沼气产率的预测值为291.8 mL·g-1TS,试验值为288.5 mL·g1TS,二者相对偏差为1.14％.因此,利用响应面分析法进行粪秸混合厌氧发酵产沼气工艺参数的优化是可行可靠的,可以较好地预测沼气产率.     

生态旅游区资源评价与保护性开发

以东北东部的主要生态旅游区——方正原始森林生态旅游区为例，根据最新国家标准，对旅游区的旅游资源进行了调查、分类和评价。结果表明：其自然景观良好，原始性很强，适合开展生态旅游。对该区进行保护性开发，在功能分区与景区、景点规划方面要以环境保护为前提，同时提出了旅游区环境保护监测系统及生态环境建设的相关建议，以保证生态旅游的真正实现。     

Genome-wide comparison of Carnobacterium maltaromaticum derived from diseased fish harbouring important virulence-related genes

Although Carnobacterium maltaromaticum has been used as a probiotic in fish, it was reported to cause disease for the first time in Korea. The objective of this study was to understand the differences between pathogenic and non-pathogenic strains. Pathogenicity was tested by challenging rainbow trout with C. maltaromaticum ATCC35586 and 18ISCm isolated from diseased fish, and DSM20342 isolated from a dairy product. We also compared 24 genomes of C. maltaromaticum strains plus the genome of our isolate 18ISCm sequenced in this study. Only the strains from diseased fish caused high mortality with severe histopathological changes. Although all strains shared more than 90% of Ko_id, wecC and xtmA were found only in strains from diseased fish. Interestingly, only strains from diseased fish harboured two wecC paralogs involved in the production of D-mannosaminuronic acid which is a major component of a well-known virulence factor, teichuronic acid. Two wecC paralogs of 18ISCm were increased when they were co-cultured with trout blood cells, suggesting that wecC genes might play a role in virulence. The results of this study show that strains isolated from diseased fish are different from strains derived from food in terms of pathogenicity to fish and the presence of virulence-related genes.     

孵卵温度与中华鳖性别决定

采用不同的孵化温度孵化同一批中华鳖受精鳖卵，于相同条件下饲养150天后鉴定它们的性别。结果表明在32℃条件下孵化的中华鳖雄性比例达到72．1％，而在27℃条件下孵化的中华鳖雄性比例则只有42．3％。由此证明：通过人为控制孵化温度可以决定中华鳖的性别比例，其结论是孵化温度较高，则雄性比例较大。该结论为有目的地人为决定中华鳖性别提供了科学依据。     

Osteological development and anomalies in larval stage of hatchery‐reared yellow catfish Pelteobagrus fulvidraco

Comprehensive knowledge of osteological development of fish not only provides means for understanding its functional development, but also allows early detection of skeletal anomalies. The present study was conducted to determine osteological development and occurrence of anomalies from the first to the 40th day after hatching (DAH) for yellow catfish Pelteobagrus fulvidraco, a commercially important species in China. Vertebral ontogeny started with formation of anterior neural arches at 3 DAH, and completed at 6 DAH. Vertebral centra started to develop at 4 DAH and ossification in all centra was visible at 15 DAH. Caudal fin appeared at 2 DAH and ossification was visible at 26 DAH. The onset of dorsal and anal fins appeared at 4 DAH and their ossifications were visible at 20 DAH. Pectoral fins were present before first feeding and formed entirely at 9 DAH, and their ossifications were visible at 21 DAH. Pelvic fins appeared at 9 DAH, and formed completely at 21 DAH. The ossification of pelvic fins was not finished until the end of the experiment (40 DAH). 24 types of skeletal anomalies were observed. About 20% of individuals showed at least one anomaly. Haemal vertebrae anomalies occurred at the highest frequency, followed by pre‐haemal, caudal vertebrae and anal fin anomalies, and caudal fin had the lowest anomalies frequency. For the first time, our study determined osteological development and anomalies incidence in larval yellow catfish, which help further investigations into rearing conditions leading to appearance of these anomalies to prevent their incidence.     

异育银鲫体内阿维菌素血脑屏障渗透性及组织残留

采用脑组织匀浆法和高效液相色谱法(HPLC), 检测异育银鲫(Carassius auratus gibelio)体内不同浓度下阿维菌素(Avermectin, AVM)血脑屏障渗透性及其组织残留情况。结果显示, AVM在其3个半数致死浓度(24 h LC₅₀: 0.127 mg/L、48 h LC₅₀: 0.071 mg/L、96 h LC₅₀: 0.039 mg/L)及其安全用药浓度(0.003 9 mg/L)下, 均能从异育银鲫脑组织中检测出AVM; 其中24 h LC₅₀浓度下脑中AVM含量最高, 为(0.292±0.005) μg/g; 并且各半数致死浓度之间脑中AVM含量差异均极显著(P<0.05)。结果表明, 不同浓度条件下AVM均能渗透通过血脑屏障进入异育银鲫脑组织, 其含量与AVM用药浓度呈正相关。另外, 在安全用药浓度(0.003 9 mg/L)条件下, AVM在各组织中的浓度−时间数据经DAS 3.0药物代谢动力学软件拟合后发现均符合非房室模型, 其主要药代动力学参数大小关系表现为: (1)达峰时间(T_max): 肌肉<脑<肝<肾; (2)峰浓度(C_max): 肝>肾>肌肉>脑; (3)末端消除半衰期(T_1/2Z): 肝>脑>肾>肌肉; (4)药时曲线下面积(AUC): 肝>肾>脑>肌肉。本研究结果可为研究鱼类血脑屏障、AVM神经毒性及其在水产养殖上的应用提供参考。

     

励珂健喷剂对10日龄内仔猪腹泻和免疫力的影响

为研究励珂健喷剂（主要成分：杨树花提取物）对10日龄内仔猪腹泻和免疫力的影响,将18头PIC母猪随机分成3组,每组6头,分别为蒸馏水组、土霉素组和励珂健喷剂组,蒸馏水组仔猪1、3、5日龄时皮肤喷洒蒸馏水1 m L/头/d,土霉素组仔猪3、7日龄时分别肌肉注射20%长效土霉素注射液0.2 m L/头/d、0.5m L/头/d,励珂健喷剂组仔猪1、3、5日龄时皮肤喷洒励珂健喷剂1 m L/头/d。结果表明,励珂健喷剂可有效降低10日龄内仔猪的腹泻率和发病率,且励珂健喷剂组腹泻仔猪的治愈速度快于土霉素组和蒸馏水组。由此证明：励珂健喷剂对10日龄内仔猪腹泻有防治作用,并且还可以增强仔猪的免疫力。     

龟鳖废水处理系统中细菌群落组成及动态变化

为了优化废水处理系统的菌群结构,提高水质净化效率,实验采用高通量测序技术对龟鳖废水处理系统的细菌群落组成进行分析,同时对细菌群落和废水水质进行相关性分析.结果显示:不同处理单元中的菌群结构存在显著差异,在门分类水平上,各处理单元的主要细菌类群为变形菌门(Proteobacteria)、拟杆菌门(Bacte-roidot...