两株H6N8亚型禽流感病毒分离株的分离与鉴定

为了解禽流感病毒(AIV)在我国华南地区的流行情况,我们对活禽市场中分离得到的两株鸭源H6N8亚型AIV[A/duck/Fujian/S2191/2011 (H6N8) (FJ/191/11)和A/duck/Guizhou/S4035/2011 (H6N8) (GZ/035/11)]进行全基因序列测定,并进行其对SPF鸡和BALB/c小鼠的致病性试验.序列分析显示:HA裂解位点基序为339pQIETR ↓GLFG348,为低致病性AIV特征.内部基因分别源于两个国内流行的H6亚型病毒家系(ST339-like和HuN573-like).序列分析表明FJ/191/11和GZ/035/11为H6亚型病毒与其他亚型AIV的N8NA基因发生重组,呈现明显的异源性.两分离株的感染性试验显示,它们对鸡和小鼠均呈低致病性;而且不能在鸡体内有效复制;对小鼠的感染性实验结果显示,小鼠肺脏和鼻甲病毒分离结果为阳性,其他脏器病毒滴定结果为阴性.     

一株鸭源H5N2禽流感病毒全基因组序列分析及对鸡的致病性研究

2012年在我国重庆市活禽交易市场进行流行病学调查时,从鸭体内分离到1株H5N2亚型禽流感病毒(AIV),DK/CQ036/12(H5N2).为了解该株H5N2亚型AIV的生物学特性,本研究对其进行了全基因组分析及对SPF鸡和BALB/c小鼠的致病性试验.序列分析显示:HA裂解位点序列为341R-----346TRGLF350,为低致病性AIV特征.内部基因来源较复杂,与KD/CQ/036/12分离株的M基因NP基因同源性最高的病毒株均来自H4、H7等亚型分离株,呈明显的异源性.分离株的感染性试验显示,该分离株在鸡体内可以通过呼吸道和消化道向外排毒,但并不能在鸡体内有效的复制.对小鼠的感染性试验结果显示,仅在鼻甲和肺能检测到病毒存在,其他脏器病毒滴定结果为阴性,表明病毒对鸡和小鼠均呈低致病性.     

两株H9N2亚型禽流感病毒的遗传演化及其致病性分析

为了解H9N2亚型禽流感病毒(AIV)的分子特征及其对家禽和哺乳动物小鼠的致病性,本研究对2020年分离到的两株H9N2亚型AIV:A/chicken/Jiangsu/S1625/2020(H9N2)(简称CK/JS/S1625/2020)株和A/duck/Sichuan/S1537/2020(H9N2)(简称DK/SC/S1537/2020)株,进行了基因组测序、序列分析及其对SPF鸡、鸭和BALB/c小鼠的致病力评价。同源性分析结果显示,两株病毒HA和NA基因的同源性分别为93.3%和95.8%,其编码氨基酸序列的同源性分别为95.4%和95.9%,同源性较低。且两株病毒HA蛋白裂解位点分别为~(333)PSRSSR↓GLF~(341)、~(333)PSRSNR↓GLF~(341),均不存在多个连续的碱性氨基酸,符合低致病性禽流感病毒(LPAIV)HA序列特征。两株病毒的HA蛋白均为典型的人源受体结合特征,即~(155)T、~(183)N和~(226)L。遗传演化分析结果显示,两株病毒的HA、NA基因均属于欧亚分支,但二者的亲缘关系较远。鸡感染性试验结果显示,CK/JS/S1625/2020株感染组鸡可通过喉头和泄殖腔向外界环境排毒。虽然在全部鸡的喉头中检测到了DK/SC/S1537/2020株,但仅在部分鸡的泄殖腔检测到了该病毒,且喉头的排毒量明显高于泄殖腔。鸡血清抗体检测结果显示,两株病毒感染鸡血清的HI抗体全部阳转,效价在1.128～1.2 048。表明,鸡源H9N2病毒比鸭源H9N2病毒在鸡体内的适应性和复制能力更强;鸭感染性试验结果显示,两株病毒均只能通过鸭的喉头向外界环境排毒,但病毒滴度均较低,且均不能在鸭体内有效复制;小鼠感染性试验结果显示,两株病毒仅能在小鼠的鼻甲中有效复制,而在小鼠的脑、脾脏和肾脏中均未检测到病毒。以上结果表明两株H9N2亚型AIV对家禽和小鼠均呈低致病力。本研究为进一步了解H9N2 AIV提供了一定的参考数据,有必要对自然界中传播的H9N2流感病毒持续监测和进化分析。     

一株野鸟源H9N2亚型禽流感病毒的全基因组序列分析及致病性研究

为进一步了解2014年分离自我国南方野鸟粪便中的一株H9N2亚型禽流感病毒(AIV)Wide Bird/Hu N/SC1400/2014(H9N2)(WB/400/14)的生物学特性,本研究对其进行全基因组序列测定、进化分析及SPF鸡、SPF鸭和BALB/c小鼠的感染性试验。序列分析显示:该分离株的HA裂解位点基序为333PAASDR↓GL340,其中不存在多个连续的碱性氨基酸,符合低致病性禽流感病毒(LPAIV)氨基酸序列特征。该分离株不同基因片段来源较复杂,分别与H9、H6、H4、H1、H11、H10、H3等多种亚型的LPAIV同源性较高,呈现明显的多样性。感染性试验显示,WB/400/14不能够在SPF鸡和小鼠体内有效复制,但病毒感染SPF鸭后能够在部分脏器中检测到病毒的存在,并且感染鸭能通够过咽喉和泄殖腔同时向外排毒,而同居感染鸭仅通过泄殖腔向外排毒,表明分离株在SPF鸭群中具有良好的水平传播能力。本研究为AIV的监测和防控提供实验依据。     

两株H4N3禽流感病毒全基因组序列分析及对小鼠的致病性研究

2009年在我国南方活禽交易市场进行流行病学调查时,从鸭体内分离到2株H4N3亚型禽流感病毒(AIV),DK/FJ/S1419/09(H4N3)(FJ/419/2009)和DK/HUN/S1010/09(H4N3)(HuN/010/2009)。为了解这2株H4N3亚型AIV的生物学特性,本研究对其进行全基因组分析及对小鼠致病性研究。结果显示:其HA基因来源于近两年流行的H4亚型病毒株,NA基因来源于其它亚型病毒株。内部基因来源较复杂,与FJ/419/2009内部基因同源性最高的病毒株均来自国内H5、H6等亚型分离株,但与HuN/010/2009同源的内部基因则差异较大,与PA、M和NS同源性最高的病毒株分别为A/wild/duck/Korea/UP122/2007(H1N1),A/muscovy/duck/Thailand/CU-LM1983/2009(H4N6)and A/avian/Japan 8KI0068/2008(H3N6)。用106EID50病毒剂量感染6周龄BALB/c小鼠,结果显示试验组小鼠感染后第3 d采脏器样品,仅在鼻甲和肺部能检测到病毒存在。以上数据表明,尽管这2株H4N3特殊亚型组合病毒来源复杂,但对小鼠的致病性较低。     

两株鸭源H6N2亚型禽流感病毒的序列分析及对鸡的致病性研究

为了解鸭源H6N2亚型禽流感病毒(AIV)的生物学特性,本研究对两株鸭源H6N2亚型AIV [A/duck/Hube/Sd061/2008(HB/061/08)和A/duck/Fujian/S2080/2009(FJ/080/09)]进行序列分析和致病性试验.序列分析显示:两株病毒的HA和NA基因均来源于我国近年流行的H6亚型病毒株,但是HB/061/08株的内部基因可能来源于H9、H5等其他亚型.与病毒株HB/061/08 NP、PA、PB2基因的核苷酸同源性最高的病毒株为A/environment/Hunan/2-84/2007(H9N2);与M、PB1和NS基因的核苷酸同源性最高的病毒株分别为A/duck/Zhejiang/11/2000(H5N1)、A/chicken/Hebei/7/2008(H9N2)和A/chicken/Henan/L1/2008(H9N2).两株病毒的抗原差异性较显著,相关系数为0.49;用106 EID50病毒剂量感染4周龄SPF鸡,结果显示FJ/080/09株不能感染鸡,而HB/061/08株在鸡体内能够高效复制,并通过咽喉和泄殖腔持续排毒.鸡群感染后第3d采取脏器样品,在气管和肺部能够检测到病毒存在,部分脏器和器官的组织学观察显示存在一定程度的病理变化.以上数据表明,H6亚型AIV在跨越不同宿主感染的传播过程中,对新宿主适应能力的差异导致对其致病性的差异.     

1株H6N6亚型禽流感病毒贵州分离株HA和NA基因克隆与序列分析

为了解 H6亚型禽流感病毒(AIV)在贵州地区的流行情况,本研究对2014年从贵州省三穗鸭体内分离鉴定出的1株H6N6亚型AIV (A/duck/Guizhou/013/2014) HA和NA基因进行了克隆和序列分析。结果显示,A/duck/Guizhou/013/2014的HA基因与华东地区2009年鸭源H6N6亚型AIV同源性最高,达97.5%,HA蛋白裂解位点的氨基酸序列为P-Q-I-E-T-R-G,符合低致病性AIV的分子特征;而NA基因则与福建2007年鸭源H6N6亚型AIV同源性最高,达98.2%;由遗传进化树分析结果可知,HA和NA基因在遗传进化关系上,与湖南毒株位于同一分支,而与2007年贵州分离的3株H6N6亚型AIV不处于同一分支,说明A/duck/Guizhou/013/2014与本地区的H6N6亚型AIV亲缘关系较远。本研究结果表明当前贵州地区H6N6亚型AIV存在明显的遗传多样性。     

两株鹅源H6N2亚型禽流感广东分离株的全序列分析及致病性研究

为了解禽流感病毒(AIV)的变异情况,本研究对我国禽流感监测期间分离鉴定的两株鹅源AIVA/Goose/Guangdong/362/2009(H6N2)(GD/362/09)与A/Goose/Guangdong/244/2010(H6N2)(GD/244/10)进行全基因序列的测定和分析,并进行其对SPF鸡和BALB/c小鼠的致病性试验。序列分析显示:HA裂解位点的序列为339PQIETR↓GLFG348,表明两株病毒均为低致病力AIV。HA和NA的核苷酸同源性分别为84.5%和98.9%,另外,序列分析结果显示,GD/244/10的PA、M基因分别与高致病性AIV(HPAIV)A/aquatic bird/Korea/w74/2005(H5N2)和A/duck/Hong Kong/140/1998(H5N1)的同源性最高,表明其内部基因来源复杂,可能与H5 HPAIV发生重组或有共同的来源。病毒对动物的致病性试验结果显示:两株病毒均不能在鸡体内有效复制,在小鼠的肺脏能够有效复制,但在小鼠的鼻甲内只能检测到GD/244/10。     

一株鸭源H11N3亚型禽流感病毒的遗传进化分析及对小鼠的致病性研究

为了解H11N3亚型禽流感病毒(AIV)的生物学特性，本研究对2020年在福州市某活禽市场鸭中分离的一株H11N3亚型AIV进行了全基因组测序、遗传进化分析和对BALB/c小鼠的致病性试验。测序结果显示，分离株HA裂解位点为PAIASR↓GLF，符合低致病性AIV分子特征；HA蛋白²²⁶L和²²⁸S突变显示病毒具有结合人源受体(SAα-2,6 Gal)的特征性氨基酸。PB1、PA、NP和M1蛋白均出现对哺乳动物致病性增强的特征性氨基酸。遗传进化分析显示，H11N3 AIV的8个基因节段均属于欧亚分支，其HA基因与A/duck/Fujian/SD061/2017 (H11N3)株HA基因序列相似性最高，而NA基因与A/EN/Fujian/02754/2016 (H3N3)株NA基因序列相似性最高。该病毒内部基因分别与浙江、福建和云南等地鸭和鸡体内分离的H7N9、H7N7、H1N2、H7N2、H7N7和H9N6等亚型AIV相关基因高度同源。小鼠致病性试验结果显示，该病毒未经适应即可在小鼠鼻甲和肺脏中高效复制，表明该病毒株具备感染哺乳动物的能力。上...     

中国首株H13N6亚型禽流感病毒遗传进化分析及致病性和传播性评估

为了解我国首次分离的H13N6亚型禽流感病毒(AIV)生物学特性,本研究对该分离株进行全基因序列测定和分析,并对其进行BALB/c小鼠和SPF鸡致病性试验以及豚鼠传播试验。序列分析表明HA碱性裂解位点序列为PAISNR↓G,为低致病性AIV。遗传进化分析表明NA基因属于北美谱系,其余7个基因均属于欧亚谱系;其中NA、NP、M、NS基因来源于鸥类,而HA、PB2、PB1、PA基因来源于野鸭类。动物致病性和传播试验结果显示,该病毒株在鸡和小鼠体内不能进行有效复制,在豚鼠和鸡体内也不能进行排毒和有效传播。基因序列分析结合致病性和传播性试验表明H13N6亚型AIV分离株可能是通过候鸟迁徙而传入我国的新型重组AIV,但该病毒株仍只能感染野生水禽尚未获得跨越种间屏障感染陆生家禽和人的能力,尚不具备哺乳动物间和家禽间的传播能力。     

白术、微米白术和白术多糖对断奶仔猪生长性能和肠道形态及微生态区系的影响

试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。     

Feline intracranial neoplasia: retrospective review of 160 cases (1985-2001)

The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

Y‐chromosomal variation of local goat breeds of Turkey close to the domestication centre

Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.     

The Prevalence and Intensity of Helminth and Coccidial Infections in Dairy Cattle in Central Kenya

A survey of gastrointestinal parasite infections of young (<6 months old), immature (6–12 months old) and adult (>12 months old) dairy cattle on 16 farms in Kiambu District, Kenya was conducted during a dry season (September 1991 to January 1992) and during a wet season (March to July 1992). The survey was based on monthly coproparasitological examination of cohorts and worm counts in tracer calves. The effects of age, sex, farm and season on the prevalence and intensity of helminth and coccidial infections were determined. Faecal egg and oocyst counts revealed that the overall prevalences were: strongyles (including trichostrongyles) (85.5%), liver flukes (Fasciola gigantica) (34.0%), coccidia (30.9%) and tapeworms (9.6%). Eight species of the protozoan Eimeria were identified, the most prevalent species being E. bovis and E. zuernii. The most prevalent nematode genera were Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus. Season, farm and age of the animals had a significant (p<0.05) influence on the intensity of infection with strongyles, liver flukes and coccidia, whereas the sex of the animals had no significant (p>0.05) effect on the prevalence or intensity of infections. A higher intensity of infection with strongyles and coccidia was found in the wet season than in the dry season (p<0.05). The age-specific intensity was in the following order: for strongyles, immature animals of 6–12 months of age had the highest egg counts, followed by young calves and adults. Calves had significantly (p<0.05) higher oocyst counts than immatures or adults. Liver fluke egg counts did not differ significant (p>0.05) between immatures and adult cattle.     

A brief history of the prevention of infectious diseases by immunisations

Infectious diseases have always been a terrible scourge for humans. The appearance of these plagues, as they were called without distinction, was generally connected to various conditions: asters, climatic changes or religious reasons. The concept of contagious, and then infectious, diseases came slowly. Variolation, i.e. transmission of ‘virulent’ matter to induce a natural disease and the immunity against it, was brought from Constantinople to England by Lady Montague, in 1721. This ‘variolation’ technique was also often performed in veterinary medicine against diseases like sheep-pox or pleuropneumonia. As ‘vaccination’ is the term generally accepted for ‘immunisation’, variolation can be the word designating such a technique. The second period of the history of immunisation began, in 1880, with the studies of Pasteur and his collaborators. A great number of bacterial vaccines were developed: dead, live but attenuated or only parts of pathogens. The viruses were produced in animals, then in eggs and at last, in tissue cultures. Second generation vaccines appeared with genetic engineering: recombinant vaccines, vector vaccines, nucleic acids vaccines, and markers vaccines, among others. These novel technologies can permit the development of new ones and improve the quality of the vaccines already existing.     

Micronutrient Content of Certain Tropical Conventional and Unconventional Feed Resources of Southern India

The ash, silica and certain important micronutrients were estimated in conventional and unconventional feed and fodder resources available in Southern India. Commonly used dry roughages, such as paddy straw, ragi straw, maize kadbi/stalk, jowar kadbi/stalk, bajra stalk and wheat straw, were high in ash (9.9% +/- 0.77%) and silica (6.4% +/- 0.65%) and low in most of the other micronutrients, except iron, with paddy straw containing most silica (>9%). Cultivated non-leguminous (maize, jowar) and improved green crops (hybrid napier, guinea, green panic, NB-21, CO-1) were also high in ash (10.5% +/- 0.60% and 12.5% +/- 0.51%) but were moderate sources of P, Mg and Cu and good sources of Zn (98 +/- 13.8 ppm and 55 +/- 6.7 ppm). Leguminous green fodders (stylosanthus, lucerne, cow pea, soyabean) were excellent sources of Ca (1.9% +/- 0.16%), Mg (0.40% +/- 0.05%), Cu (30 +/- 5.2 ppm), Zn (121 +/- 14.7 ppm) and Fe (1234 +/- 166 ppm) and moderate sources of P. Mixed local grasses and weeds were high in silica (6.9% +/- 1.00%) but were good sources of Cu, Zn and Fe. Cereal grains (maize, wheat, rice, ragi) were low in ash (2.9% +/- 0.33%) and were relatively poor sources of Ca (0.22% +/- 0.03%), Mg (0.19% +/- 0.03%) and Cu (13 +/- 3.1 ppm). Pulses were low to medium sources of most minerals and good sources of Fe (1230 +/- 293 ppm). Oil seed cake/extractions (groundnut cake, cotton seed cake, soyabean meal, sunflower cake, safflower cake) and cereal by-products (rice polish, rice bran, wheat bran) were excellent sources of P (1.1% +/- 0.47% and 2.3% +/- 0.19%) and good sources of Zn (65 +/- 3.9 ppm and 66 +/- 10.7 ppm) and Fe (938 +/- 130 ppm and 662 +/- 126 ppm). Among the unconventional feeds screened, orange peel, sunflower heads, meat meal, rubber seed cake, spirulina algae and sea weeds contained plentiful Ca, Zn and Fe: tree leaves/top feeds (mulberry, erythrina, glyricidia, banana, subabul, groundnut haulms) were excellent sources of Ca (1.5% +/- 0.13%), Zn (120 +/- 22.9 ppm) and Fe (1033 +/- 133 ppm) but relatively poor sources of P. Soyabean husk, cocoa seed husk, rubber seed cake and meat meal were moderate to good sources of P (1.0% and 0.33%). The high Zn and Fe values of most feeds/fodders were probably due to soil contamination. This account of the micronutrient content of feed/fodder resources should help in strategic supplementation intended to alleviate local deficiencies.     

Bovine Mastitis in Selected Areas of Southern Ethiopia

A study on bovine mastitis, designed to determine the causal agents, prevalence of infection and impact of risk factors in three cattle breeds, was conducted in selected areas of southern Ethiopia. A total of 307 lactating and non-lactating cows, of which 162 were indigenous Zebu, 85 Jersey and 60 Holstein-Friesian, were examined by clinical examination and the California mastitis (CMT) test. Of these, 40.4% were positive by CMT and bacteriology for clinical or subclinical mastitis, with prevalence rates of 37.1% and 62.9%, respectively. Out of 1133 quarters examined, 212 (18.7%) were found to be infected, 83 (39.2%) clinically and 129 (60.8%) subclinically. The prevalence of mastitis was significantly higher in Holstein-Friesian than in indigenous Zebu, in non-lactating cows than in lactating cows, in the early lactation stage than in the mid-lactation stage, in cows with lesions and/or tick infestation on skin of udder and/or teats than in cows without this factor, and in the wet season than in the dry season. Mastitis increased with parity number (R = 0.9). Of 248 CMT and clinically positive udder quarter samples analysed microbiologically, 212 were culturally positive for known mastitis pathogens and 36 were negative. Of the 199 positive samples, Staphylococcus accounted for 39.2%, Streptococcus for 23.6%, coliforms for 14.1%, Micrococcus and Bacillus species for 8.0% each and Actinomyces or Arcanobacterium (Corynebacterium) for 7.0%. It was concluded that there was a high prevalence of clinical and subclinical mastitis, mainly caused by Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli, in this study area.     

不同日粮氮水平对山羊氮代谢和微生物蛋白质合成的影响

本试验旨在探讨不同日粮氮水平对内蒙古白绒山羊氮代谢和微生物蛋白质合成(MCP)的影响,以达到提高氮利用率,减少环境污染和饲料资源的浪费。试验选用9只体况良好、体重为(43.83±2.95)kg,装有瘤胃瘘管的内蒙古白绒山羊,按体重随机分为3组,每组3只。日粮分为低氮7.5%、中氮10.5%、高氮13.5%3个氮水平。试验使用常规试验方法分析测定粪尿血液等生化指标,通过全收尿法和尿嘌呤衍生物法估测MCP。结果表明:随着氮水平增加,氨氮(NH3-N)浓度、氮摄入量、尿氮排出、尿中尿素氮(UUN)和MCP显著增加(P0.05),干物质采食量(DMI)显著降低(P0.01);沉积氮占总摄入氮的比例在中氮组最高,MCP在高氮组最高。综上所述,适当降低日粮氮水平可减少粪尿氮排放,提高反刍动物氮利用率。