舒巴坦、利血平、乙二胺四乙酸二钠对鸭源大肠杆菌抗菌药物敏感性的影响

本试验旨在研究β-内酰胺酶抑制剂舒巴坦、外排泵抑制剂利血平及膜通透促进剂乙二胺四乙酸二钠(EDTA)对鸭源大肠杆菌抗菌药物敏感性的影响。采用微量肉汤稀释法测定8株多重耐药鸭源大肠杆菌对头孢噻呋钠、恩诺沙星、阿米卡星、氟苯尼考、多西环素及其与舒巴坦、利血平和EDTA联用的最小抑菌浓度(MIC)。结果表明,舒巴坦能使5株鸭源大肠杆菌对头孢噻呋钠的MIC值下降4倍以上;利血平仅能使3株菌株对头孢噻呋钠的MIC值下降4倍以上;而EDTA能使7、5、3、6、8株菌对以上5种药物的MIC下降4倍以上;舒巴坦+利血平使4株菌株对头孢噻呋钠的MIC下降4倍以上,使5株菌株对氟苯尼考的MIC下降4倍以上;舒巴坦+EDTA使鸭源大肠杆菌对以上5类药物的MIC大幅度下降,分别使8、5、2、8、8株菌MIC下降4倍以上;利血平+EDTA使7株菌株对恩诺沙星MIC下降4倍以上,使所有分离株对其余4种药物的MIC显著下降;舒巴坦+利血平+EDTA和5类药物联用后,所用分离株的MIC下降4倍以上。由此可见,引起鸭源大肠杆菌对以上抗菌药物的耐药原因主要包括细胞膜通透性的下降、药物的主动外排作用和产生β-内酰胺酶的破坏作用,三者相协同提高了鸭源大肠杆菌的耐药水平。     

Immune response and protective efficacy against homologous challenge in BALB/c mice vaccinated with DNA vaccine encoding Toxoplasma gondii actin depolymerizing factor gene

A DNA vaccine (pVAX1-TgADF) encoding Toxoplasma gondii actin depolymerizing factor (ADF) gene was constructed and the immune response and protective efficacy of this vaccine against homologous challenge in BALB/c mice were evaluated. High titers of specific antibody and increases in the percentage of CD4(+) and CD8(+) T lymphocyte cells were observed from BALB/c mice vaccinated with pVAX1-TgADF (P<0.05), when PBS group was used as control. The survival time of BALB/c mice in pVAX1-TgADF group was longer than those in control groups. The numbers of brain cysts in the experimental BALB/c mice immunized with pVAX1-TgADF reduced significantly compared with those in PBS group (P<0.05), and the rate of reduction could reach to around 42.8%. These results suggested that the DNA vaccine pVAX1-TgADF could generate specific humoral and cellular immune responses, prolong survival times, and reduce brain cysts load against T. gondii infection in BALB/c mice.     

Effects of tryptophan supplementation on aggression among group-housed gestating sows

The objective of this study was to determine the effects of dietary Trp supplementation on mixing-induced aggression and the associated stress, and on reproductive performance in gestating sows. After weaning, sows were mixed in pens with electronic sow feeders on concrete-slatted floors. Each pen housed 21 ± 2.8 sows, with approximately 2.7 ± 0.43 m(2)/sow of floor space allowance. Multiparous sows (n = 168) from 8 breeding groups were used, with 4 groups assigned to a control diet and 4 groups assigned to a high-Trp diet. Control sows received corn- and soybean meal-based diets throughout gestation (0.15% Trp) and lactation (0.21% Trp). Three days before and after mixing, sows assigned to the high-Trp treatment received approximately 2.3 times the dietary Trp (0.35% in the gestation diet and 0.48% in the lactation diet) fed to control sows. Six focal sows (2 sows from each of parity 1, 2, and 3 or greater) in each pen were designated and videotaped for 72 h after mixing to determine the type and number of aggressive interactions among sows. Before and 48 h after mixing, saliva samples were collected from focal sows, and scratches were assessed on all sows. Data were analyzed using the FREQ and GLIMMIX procedures (SAS Inst. Inc., Cary, NC). Aggression among sows was intense during the initial 6 h and decreased between 6 and 72 h after mixing. The initial aggression caused scratches and increased cortisol concentrations (P < 0.05). Mature sows tended to fight for longer periods (112 vs. 52 s/h per sow, SE = 23.8; P < 0.10) but had fewer scratches caused by aggression (injury score = 4.3 vs. 6.5, SE = 1.13; P < 0.01) than parity-1 sows. Supplementation of dietary Trp reduced the total duration of head-to-head knocking (P < 0.05) but did not affect other aggressive behaviors. There was no difference between dietary treatments in injury scores or saliva cortisol concentrations. Sows in the high-Trp treatment had more total piglets born (12.5 vs. 10.5 pigs/litter, SE = 0.55; P < 0.05) and more stillborn piglets (1.5 vs. 0.8 pigs/litter, SE = 0.20; P < 0.05), but had no significant change (P = 0.12) in piglets born alive (10.8 vs. 9.7 pigs/litter, SE = 0.42) compared with control sows. The results indicate that the initial aggression after mixing caused more injuries in young sows than in mature sows. Supplementation of dietary Trp at 2.3 times the control amount for a short period did not effectively reduce aggression and the associated stress in sows at mixing.     

猪育种中DNA标记辅助选择方法的研究进展

DNA标记辅助选择（简称MAS）为猪的育种提供了一个新的突破性方法,作者将从MAS的原理和实施方案、猪的基因图谱、猪育种中的若干重要DNA标记、MAS应用效果的理论研究和MAS应用实践等方面,综述其在猪育种中的应用研究进展。     

苜蓿叶象甲的耐寒性研究

为探讨苜蓿叶象甲(Hypera postica)的耐寒性,测定了不同虫态以及越冬成虫的过冷却点和冰点.结果表明,苜蓿叶象甲成虫、长翅型蛹、短翅型蛹、四龄幼虫以及三龄幼虫的过冷却点依次为-20.46、-10.34、-9.55、-10.0和-9.75℃,冰点依次为-18.24、-6.68、-6.52,-7.52和-7.86...     

激素对白三叶愈伤组织形成的影响及体细胞胚的组织学观察

以白三叶3个品种瑞文德、铺地和海法的子叶和下胚轴为外植体,采用正交设计试验研究2,4-D、6-BA和KT三种生长调节剂的不同浓度水平对白三叶愈伤组织诱导及继代的影响,筛选最佳激素组合并进行体细胞胚的组织学观察.结果表明:同一品种同一时期不同外植体愈伤诱导的最佳激素组合不相同,不同品种间也不一致;瑞文德子叶胚性愈伤诱导的最佳培养基为改良SH+2,4-D 2mg/L+6-BA 0.35mg/L+KT 0.5mg/L,下胚轴为改良SH+2,4-D 2mg/L+6-BA 0.2mg/L+KT 0.35mg/L;铺地子叶胚性愈伤诱导的最佳培养基为改良SH+2,4-D 2mg/L+6-BA 0.5mg/L+KT 0.5mg/L,下胚轴为改良SH+2,4 D 5mg/L+6-BA 0.35mg/L+KT 0.5mg/L;海法子叶胚性愈伤诱导的最佳培养基为改良SH+2,4-D 2mg/L+6-BA 0.2mg/L+KT 0.35mg/L,下胚轴为改良SH+2,4-D5mg/L+6-BA 0.5mg/L+KT 0.5mg/L.组织学观察表明,体细胞胚的发育经历球形胚、心形胚、鱼雷胚及子叶胚四个阶段后形成一个完整的体细胞胚.     

海洋生态资本理论框架下海洋生物资源的存量评估

海洋生态资本是能够直接或间接作用于人类社会经济生产、提供有用的产品流或服务流的海洋生态资源.海洋生态资源包括海洋生物资源及其生境资源.海洋生态资源的存量价值由海洋生物资源存量价值和海洋生境资源存量价值构成.针对我国海洋生物资源的特征,在海洋生态资本理论框架下,提出了鱼类、贝类、甲壳类、头足类、大型海藻等主要海洋生物资源的存量价值评估技术方法,包括物质量评估和价值量评估.探讨了海洋生物资源单位价格确定、评估价值修正、评估方法的适用性、成本扣除等问题.     

阿替美唑对小型猪特异性麻醉剂诱导大鼠大脑皮质内Fos蛋白表达的影响

研究阿替美唑对小型猪特异性麻醉剂(XFM)麻醉下大鼠大脑皮质Fos蛋白表达的影响,探讨阿替美唑颉颃XFM催醒大鼠与大脑皮质c-fos基因的关系。将72只SD纯种大鼠随机分为XFM对照组、XFM+阿替美唑组、XFM+生理盐水组,每组又按采脑时间点分成4个亚组。采用蛋白质印迹法检测大脑皮质内Fos蛋白表达量。结果表明:XFM麻醉大鼠大脑皮质内Fos蛋白表达量逐渐增加,与给药后10min比较差异显著(P<0.01或P<0.05);XFM麻醉大鼠腹腔注射生理盐水,各时间点Fos蛋白表达量与对照组间比较无显著差异(P>0.05);阿替美唑注射后引起XFM麻醉大鼠大脑皮质Fos蛋白表达量减少,与XFM对照组比较差异显著(P<0.01或P<0.05)。结果提示,大脑皮质c-fos基因参与了阿替美唑颉颃XFM麻醉作用。阿替美唑抑制XFM诱导大鼠大脑皮质Fos蛋白表达,可能是阿替美唑催醒XFM麻醉大鼠的重要机理之一。     

亚麻籽在动物生产中的应用现状

随着亚麻籽在食品工业和动物体内的广泛应用,人们对亚麻籽的研究已经成为热点。本文对亚麻籽营养成分、饲用方式及目前在动物生产中的应用现状进行综述,为未来我国进行此方面的研究提供理论基础。     

Bacteriophages as antimicrobial agents against major pathogens in swine: a review

In recent years, the development of antibiotic resistant bacteria has become a global concern which has prompted research into the development of alternative disease control strategies for the swine industry. Bacteriophages (viruses that infect bacteria) offer the prospect of a sustainable alternative approach against bacterial pathogens with the flexibility of being applied therapeutically or for biological control purposes. This paper reviews the use of phages as an antimicrobial strategy for controlling critical pathogens including Salmonella and Escherichia coli with an emphasis on the application of phages for improving performance and nutrient digestibility in swine operations as well as in controlling zoonotic human diseases by reducing the bacterial load spread from pork products to humans through the meat.