2型猪链球菌的血清学鉴定

本试验首次证实了２型猪链球菌在我国的存在，采用玻片凝集、琼脂扩散及毛细管沉淀等３项试验，对１９９０年以来广东某猪场断奶仔猪暴发流行的败血症、脑膜炎及关节炎病猪中分离的１５株链球菌进行了血清学鉴定。结果表明：１５株链球菌均为２型猪链球菌；用高压法提取抗原进行沉淀反应，其结果比酸热法提取抗原具有简便、敏感、特异性强的特点。     

猪复合预混料中微量元素含量的调查分析初探

通过对9家预混料生产厂家的4%系列猪用预混料的调查研究,以期了解预混料微量元素的含量。调查结果表明,在抽查的9家预混料生产厂家中,共45个产品中铜、铁、锰、锌的自定标准值和实测值都极大超过了中国肉脂型生长肥育猪和妊娠母猪的饲养标准(1986)和美国NRC(1998)建议的猪营养需要量。铅、砷等危害极大的元素须严格的控制。铜、铁、锰、锌等微量元素的大量添加,虽然可以提高猪的生产性能,但会对环境造成极大的危害。     

应用套入式聚合酶链反应(Nested-PCR)检测蓝舌病病毒的研究

本实验建立了一种Ｎｅｓｔｅｄ－ＰＣＲ方法。应用方法检测５株标准株蓝舌病病毒（Ｔ４、Ｔ１０、Ｔ１１、Ｔ１６、Ｔ２０）和５株国内蓝舌病病毒分离株（ＣＦ４、ＡＦ６、Ｚ１、Ｈ１、Ｇ１４）,检测结果均为阳性,而检测相关环状病毒（ＥＨＤ２、ＥＨＤ６、Ｉｂｒａｋｉ）,检测结果均生。研究证明,此方法可检测到３．５ｆｇ的ＢＴＶ－ＲＮＡ,灵敏度较高。该方法成功区分了蓝病病毒和相关环状病毒,比血清学方法更加优势,在临床     

我国部分地区Sicinivirus流行病学调查

Sicinivirus是一种禽类新发病毒,可引起家禽发育迟缓综合症、腹泻、吸收不良综合征等.目前,仅部分国家开展了该病毒的流行病学调查,研究数据极为有限.为明确该病毒在我国的流行情况,以及该病毒感染率与地域、宿主、养殖方式之间的关系,2019年下半年在江苏、广西、河北、安徽、广东、上海、湖北和江西8个省(自治区、直辖市...     

Characterization of polymorphisms of transferrin receptor and their association with susceptibility to ETEC F4ab/ac in pigs

Diarrhoea caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 (F4ab, F4ac and F4ad) fimbriae is a significant cause of mortality and morbidity in newborn and weaned pigs. The locus controlling susceptibility towards ETEC F4ab/ac has been mapped to SSC13q41, in which TFRC (transferrin receptor) was localized and considered as a positional candidate gene for ETEC F4ab/ac receptor. In this study, we determined susceptibility/resistance to ETEC F4ab/ac in a total of 755 F2 animals from a White Duroc x Erhualian intercross using a microscopic enterocyte adhesion assay. We identified two TFRC polymorphisms (SNPs 591 A>G and 632 A>G) in a single exon after comparative sequencing analysis of 2371-bp amplicons containing the complete coding region of TFRC using RNA of eight full-sib F2 animals with susceptible and resistant phenotypes. The intron sequences flanking the two exon polymorphisms were obtained, revealing an intron polymorphism (SNP 291 C>T). We genotyped the 19 founder animals of the White Duroc x Erhualian intercross for the identified polymorphisms, showing that only the 291 C>T polymorphism is a highly informative marker. We further genotyped all 59 F1 and 755 F2 animals for the 291 C>T polymorphism, and the association of this polymorphism with susceptibility/resistance to ETEC F4ab/ac in these F2 animals was evaluated by the transmission disequilibrium test. The result showed that the 291 C>T polymorphism is not a causal mutation, however, has a significant linkage disequilibrium with the ETEC F4ab/ac, especially F4ac receptor locus.     

Seasonal and photoperiodic regulation of secretion of hormones associated with reproduction in Magang goose ganders

This study examined the reproductive endocrine profile under natural and artificial photoperiods in Magang goose ganders. Group 1 ganders (n=8) served as non-treated controls and were exposed to natural photoperiod throughout the experiment from 13th January to 17th December 2004. Group 2 ganders (n=8) were exposed to 18 h long daily photoperiod for 60 days from 13 January till 15 March 2004 and again to 16 h photoperiod for 75 days till 10th October 2004, and the 11h short photoperiod in the remainder periods of the experiment. In control ganders, plasma LH concentrations were high in normal breeding seasons (August-March) and decreased to low levels in non-breeding season from April to July. Testosterone concentrations changed similarly to that of LH throughout the seasons. Seasonal pattern of PRL concentrations was opposite to those of LH and testosterone, with low values in breeding season and high values in non-breeding season. In artificial photoperiod treated ganders, increasing photoperiod increased PRL and decreased LH and testosterone concentrations, while decreasing photoperiod reversed these changes. There were no seasonal or photoperiod caused changes in plasma T3 concentrations in both control ganders and artificial photoperiod treated ganders. These results demonstrated that in Magang goose ganders that long photoperiod stimulates PRL secretion and decreases LH secretion, which terminates reproductive season in spring and early summer, and short photoperiod stimulates LH secretion and inhibits PRL secretion rendering ganders enter into reproductive season.     

多不饱和脂肪酸与免疫的关系

许多营养素如维生素、微量元素、某些氨基酸和多不饱和脂肪酸等都可以影响动物机体的免疫反应。脂肪酸是一种重要的营养素,是机体能量的主要来源,发挥着重     

堵源截流的先锋贩毒分子的克星——前进中的临沧警犬缉毒工作

在滇西南边陲临沧290.79公里的中缅边境线上,常年活跃着一支能征善战的缉毒专业队伍——临沧市公安局禁毒支队缉毒警犬防暴大队。他们在长期的禁毒斗争中取得了令人瞩目的成绩,以每年侦破数起万克以上特大案件的辉煌战绩,成为临沧边疆堵源截流的先锋,贩毒分子的克星,为减少毒品的内流,减轻毒品对社会的危害做出了突出的贡献。2000年,刑侦犬“双刮”代表云南省参加在南京举行的第一届全国警犬技术大赛,     

微胶囊技术在饲料业中的应用

介绍了微胶囊技术以及饲料业中常用的芯、壁材和微胶囊化方法,并论述了微胶囊技术在饲料业中的应用。     

SSR和ISSR分子标记及其在桑树遗传育种研究中的应用前景

本文对SSR(simple sequence repeat)和ISSR(inter-simple sequence repeat)分子标记的定义和各自优点进行了综述,并展望这两种分子标记技术在桑树遗传育种研究中的应用前景。