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排序方式: 共有283条查询结果,搜索用时 0 毫秒
201.
In Egypt, continuous circulation of highly pathogenic avian influenza (HPAI) H5N1 viruses of clade 2.2.1 in vaccinated commercial poultry challenges strenuous control efforts. Here, vaccine-derived maternal AIV H5 specific immunity in one-day old chicks was investigated as a factor of vaccine failure in long-term blanket vaccination campaigns in broiler chickens. H5 seropositive one-day old chicks were derived from breeders repeatedly immunized with a commercial inactivated vaccine based on the Potsdam/H5N2 strain. When challenged using the antigenically related HPAIV strain Italy/98 (H5N2) clinical protection was achieved until at least 10 days post-hatch although virus replication was not fully suppressed. No protection at all was observed against the Egyptian HPAIV strain EGYvar/H5N1 representing a vaccine escape lineage. Other groups of chicks with maternal immunity were vaccinated once at 3 or 14 days of age using either the Potsdam/H5N2 vaccine or a vaccine based on EGYvar/H5N1. At day 35 of age these chicks were challenged with the Egyptian HPAIV strain EGYcls/H5N1 which co-circulates with EGYvar/H5N1 but does not represent an antigenic drift variant. The Potsdam/H5N2 vaccinated groups were not protected against EGYcls/H5N1 infection while, in contrast, the EGYvar/H5N1 vaccinated chicks withstand challenge with EGYvar/H5N1 infection. In addition, the results showed that maternal antibodies could interfere with the immune response when a homologous vaccine strain was used. 相似文献
202.
高油玉米在猪和家禽中氨基酸消化率和能量利用率的研究 总被引:5,自引:0,他引:5
通过两个试验测定了两种高油玉米和普通玉米在猪和家禽中营养物质消化率和有效能。试验1选用48只33周龄海兰蛋用种公鸡,随机分为4个处理,每个处理12只鸡。前3个处理分别给每只家禽强饲50g待测原料测定氨基酸消化率,第4个处理作为对照组,绝食法测定内源排出量。试验2使用6头去势公猪,通过手术置入T型瘘管,采用重复拉丁方设计测定3种玉米的氨基酸回肠消化率和营养物质消化率。试验结果显示,随着玉米籽粒含油量的上升,两种高油玉米的总能分别比普通玉米提高了4 29%和6 23%;粗蛋白含量也分别较普通玉米提高了17 26%和35 19%。高油玉米家禽真代谢能、猪消化能和代谢能显著高于普通玉米(P<0 05);家禽氨基酸消化率3个玉米品种差异不显著。猪回肠氨基酸消化率随玉米籽粒蛋白质含量的提高有上升的趋势,其中高油玉米B的异亮氨酸,苯丙氨酸和天门冬氨酸消化率显著高于普通玉米(P<0 05);酪氨酸消化率高油玉米显著优于普通玉米(P<0 05)。平均氨基酸消化率高油玉米B高于普通玉米(P<0 05)。研究结果证实高油玉米品种比普通玉米含有更多的能量和必需氨基酸,而且氨基酸消化率和有效能含量都优于普通玉米,是一种优质高效的饲料原料。 相似文献
203.
Himel Barua Paritosh Kumar Biswas Kaisar Ali Talukder Katharina E.P. Olsen Jens Peter Christensen 《Veterinary microbiology》2014,168(2-4):372-380
We investigated Salmonella enterica isolates from human clinical cases of gastroenteritis to determine the distribution of non-typhoidal Salmonella serovars in the human population, and compared them to isolates originating from poultry by serotyping, phage typing, plasmid profiling, pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) to evaluate the potential role of poultry in human non-typhoidal salmonellosis in Bangladesh. Nine different serovars were identified among the human isolates of which Salmonella Paratyphi B var Java (S. Java), S. Kentucky, S. Enteritidis, S. Virchow and S. Weltevreden also were commonly isolated from poultry. The poultry isolates belonging to S. Java, S. Kentucky and S. Enteritidis were indistinguishable from human isolates or genetically closely related, based on PFGE profiles and MLST. S. Kentucky clone ST198 and S. Java clone ST43 both well-known cause of human infections were also isolated from poultry. 相似文献
204.
XU Ri-fu LI Kui CHEN Guo-hong QIANG Ba-yang-zong MO De-lin LI Chang-chun FAN Bin LIU Bang 《中国农业科学(英文版)》2005,4(4)
A fragment spanning over exon 2 and intron 2 of major histocompatibility complex B-LB Ⅱ genes was amplified using PCR,cloned and sequenced in 13 individuals from eight Chinese indigenous chicken breeds and one introduced breed. Another 41 sequences of MHC class Ⅱβ from ten vertebrate species were cited from the NCBI GenBank. Thirteen new B-LB Ⅱ alleles were found in the chicken breeds sampled. Alignment of the exon 2 sequences revealed 91.1-97.8% similarity to each other within the chickens sampled, and the chickens shared 84.1-87.0% homology to Phasianus colchicus, 78.5-81.5% similarity to Coturnixjaponica. The sequences in poultry showed 62.6-68.1% identity to HLA-DRBl, 50-61.5% similarity to DQB (HLA-, SLA- and H2-BB), 53.7-60% to HLA-DPB and 53.3-57.8% similarity to HLA-DOB. The frequency of nonsynonymous substitutions of nucleotide was higher than that of synonymous substitutions, and the frequencies of nonsynonymous and synonymous substitutions in poultry B-LB Ⅱ genes were lower than those observed in mammalian DRB1 and DQB1 genes. The deduced amino acid sequences of MHC class Ⅱβ1 domain exhibited extreme difference in conversed region and variable region patterns among the various species, but the two conserved cysteines forming disulfide-bond were shown consistent in poultry with that in mammalian species; and the carbohydrate attachment site was found more conserved in chicken, Homo sapiens, Bos taurus, Ovis aries and Capra hircus than in Sus scrofa and rodent animals. Compared with exon 2 of DQB1 genes of Homo sapiens, ruminant species and Sus scrofa, the differentia that the deletion of six nucleotides at position195 to 200 of exon 2 of DQB1 genes, and insertion of three nucleotides at position 247 to 249 of the exon 2 existed in rodent species were found, which led to the absence of three AA residues at position 65, 66,and 67 within β1 domain of DQB1 chain, and the insertion of one AA residue at position 85. The difference of the deletion of six nucleotides at position 72 to 77 of exon 2 of DPB1 genes was observed with Homo sapiens DQB1, which caused absence of three AA residues at position 24, 25, and 26 of β1 domain of DPBl chain. The phylogenetic tree revealed that the B-LB Ⅱ sequences from poultry are not orthologous to the class Ⅱ MHC β-chain genes of mammalian species. The tree indicated that genetic evolutionary relationship of chickens with Phasianus colchicus was much closer than with Coturnixjaponica, and the DQB and DPB clusters are more tightly related to each other than to the remaining clusters. 相似文献
205.
畜禽粪便等固体废弃物及土壤中磷的形态分析对于管理固体废弃物、提高磷素利用率、减少磷素流失风险具有重要意义。自20世纪初以来,已提出多种固体废弃物及土壤中磷素形态分析的方法,包括化学分级、酶水解法、红外光谱(FT-IR)、X射线衍射(XRD)、31P核磁共振(31P NMR)、X射线吸收近边结构(XANES)等。本文系统总结了一些固体废弃物及土壤中磷素形态分析的方法,比较了其特点,指出只靠单一的方法并不能很好的鉴定固体废弃物及土壤中磷素的形态,必须综合考虑运用多种方法,从而为磷素形态分析提供方法选择的依据,同时为进一步发展固体废弃物及土壤中磷素形态分析新技术奠定基础。 相似文献
206.
207.
中国家畜家禽寄生虫与寄生虫病概况 总被引:3,自引:1,他引:2
沈杰 《中国兽医寄生虫病》2005,13(2):1-4
为了提供我国家畜家禽寄生虫和寄生虫病总的概况,综合分析了相关资料,归纳出了我国畜禽寄生虫种类构成、分布范围、重要人畜共患寄生虫虫种、我国南北两方寄生虫种类的异同、多宿主寄生虫虫种和家畜家禽寄生虫病概况等几个方面的内容,并作了评述讨论。 相似文献
208.
209.