基于网络药理学探讨白龙散治疗鸡腹泻的作用机制

【目的】 采用网络药理学技术与方法预测白龙散治疗鸡腹泻的物质基础、作用靶点和通路。【方法】 通过中药系统药理学分析数据库TCMSP筛选中药复方白龙散中的白头翁、黄连、龙胆的有效活性成分及其潜在作用靶点。通过GeneCards和OMIM数据库检索鸡腹泻的相关疾病靶点。利用Venny平台获得药物和疾病的交集靶点。将交集靶点上传至STRING数据库进行分析,构建蛋白互作（PPI）网络图并获得关键靶点,并进一步对关键靶点进行GO功能和KEGG通路富集分析。【结果】 共筛选得到活性成分27个,药物靶点57个,疾病靶点4 207个;药物与疾病交集靶点45个。PPI网络发现原癌基因蛋白质C （MYC）、雌激素受体1（ESR1）、白细胞介素-6（IL-6）、G1/S-specific周期蛋白D1（CCND1）等45个蛋白可能是白龙散治疗鸡腹泻的关键靶点。GO功能富集分析确定了112个条目,KEGG通路富集分析确定了22条通路。【结论】 中药复方白龙散主要通过槲皮素、山奈酚、异鼠李素等多个化学成分调控转录因子AP-1（JUN）、MYC、ESR1、IL-6等靶点,作用于细胞因子-细胞因子受体相互作用、肿瘤抑制蛋白（p53）信号通路、丝裂原活化蛋白激酶（MAPK）等信号通路来治疗鸡腹泻。     

基于网络药理学和分子对接探究莱菔子的抗菌作用机制

本研究旨在通过网络药理学方法来探讨莱菔子的抗菌作用机制。利用中药系统药理学数据库、分析平台TCMSP以及GeneCards数据库获得莱菔子发挥抗菌作用的有效成分以及潜在抗菌靶点；利用Cytoscape3.8.0软件构建药物-成分-靶点-疾病网络图，并使用STRING数据库以及Cytoscape3.8.0软件构建蛋白质相互作用网络图；利用DAVID数据库对靶点进行基因本体（GO）富集分析和KEGG通路富集分析；使用AutoDock软件对关键靶点与活性成分进行分子对接，选择最佳的结合靶点。结果显示：莱菔子14个活性成分作用于36个抗菌靶点。GO功能富集分析得到185个条目，KEGG通路富集分析得到48条信号通路。分子对接显示，芥子酸、邻苯二甲酸二丁酯、亚麻子油酸等成分与细胞肌动蛋白基因（ACTB）、一氧化氮合酶基因（NOS3）等关键靶点有较强亲和能力。本试验结果表明，莱菔子可能通过参与调节磷脂酰肌醇3激酶（Phosphatidylinositol 3-Kinase,PI3K）/蛋白激酶B(Akt)信号通路（PI3K-Akt）、钙离子信号通路等发挥其抗菌作用，体现了莱菔子多成分、多靶点、多通...     

基于网络药理学探究芪姜粉治疗猪脾胃虚寒型腹泻的效果和作用机制

为了基于网络药理学方法探究芪姜粉治疗猪脾胃虚寒型腹泻的效果和作用机制，本试验借助中药系统药理学分析平台(TCMSP)对芪姜粉进行药效物质基础分析及作用靶点预测，通过GeneCards和OMIM数据库检索与腹泻相关的疾病靶点，并用Uniprot数据库进行校正；用Cytoscape 3.7.2软件构建“芪姜粉—活性成分—靶点网络图”“芪姜粉—活性成分—腹泻—靶点网络图”,利用String数据库构建蛋白相互作用(PPI)网络；在DAVID数据库中进行基因本体(GO)功能富集分析和京都基因与基因组百科全书(KEGG)通路富集分析，以预测其作用机制。结果显示，活性成分—靶点网络包含20个活性成分和相应靶点159个，关键靶点涉及PPARG、PTGS2、PTGS1、NOS2等；PPI核心网络包含101个蛋白，关键蛋白涉及TNF、TP53、IL-6、IL-8等；GO功能富集分析得到GO条目272个(P<0.05),其中生物过程(BP)条目198个，分子功能(CC)条目23个，细胞组成(MF)条目51个；KEGG通路富集筛选得到119条信号通路(P<0.05),相关度较高的疾病依次为癌症、乙...     

基于网络药理学的鹿茸调节免疫作用机制

运用网络药理学方法,探索鹿茸有效成分在免疫调节中的作用机制,在BATMAN-TCM数据库中筛选出鹿茸的有效成分并获得相应的目标信息,通过Genecards、0MIM得到免疫相关靶点信息,使用String平台建立蛋白相互作用网络,使用DAVID数据库对鹿茸调节免疫作用靶点进行GO富集分析和KEGG通路分析,利用R x64 3.4.3软件绘制GO、KEGG富集分析高级气泡图。结果表明：得到活性成分-免疫作用靶点33个,鹿茸涉及生物过程主要有炎症反应、蛋白质合成、癌症通路、NF-κB信号通路等。     

基于网络药理学探讨黄芩素治疗猪链球菌脑膜炎的分子机制

为探讨黄芩素治疗猪链球菌脑膜炎的分子机制，应用网络药理学的方法，在Pubchem和SwissTarget Prediction数据库获取黄芩素490个潜在作用靶点，并在NCBI等平台中检索猪链球菌脑膜炎的靶点。运用STRING数据库构建“中药-疾病”共同靶点的PPI网络图；利用DAVID数据库进行GO功能注释和KEGG通路富集分析，并使用Cytoscape3.8.2软件构建“中药-靶点”通路图。结果显示黄芩素和猪链球菌脑膜炎有9个共同靶点(MMP2、SYK、FN1、MAPK14、HSPCB、CASP3、CCL2、APOD、EGFR),其中MMP2、SYK和FN1是脑损伤的核心靶点。GO富集分析发现，黄芩素可能通过影响细胞凋亡的调控过程、细胞外间隙、细胞氧化应激的过程缓解猪链球菌脑膜炎的症状；KEGG通路主要富集在IL-17信号通路、MAPK信号通路等41条相关通路。基于网络药理学的结果，本研究探讨了黄芩素潜在治疗链球菌引起的脑膜炎的作用，推测该中药成分可以作为开发抗猪链球菌疾病的先导化合物，为开发治疗猪链球菌病的药物奠定研究基础。     

基于网络药理学分析银黄可溶性粉治疗猪喘气病的活性成分及作用机制

为了解银黄可溶性粉治疗猪喘气病的活性成分及作用机制，本试验采用网络药理学的方法进行探索，利用中药系统药理学数据库与分析平台(TCMSP)获取银黄可溶性粉的活性成分及对应的靶点，将靶点导入Uniprot数据库，利用Cytoscape 3.5.0软件构建药物-活性成分-靶点网络图，在Genecards数据库和人类孟德尔遗传数据库(OMIM)获取猪喘气病的靶点，将靶点导入Uniprot数据库，通过STRING数据库构建蛋白相互作用(PPI)网络图，在生物学信息注释数据库(DAVID)进行基因本体(GO)富集分析和基因组百科全书(KEGG)信号通路富集分析。结果显示，银黄可溶性粉筛选出48个活性成分，155个靶点；猪喘气病有关的靶点有3 154个；PPI网络有51个靶点，关键靶点有血管内皮生长因子A(VEGFA)和肿瘤坏死因子(TNF)等；GO功能注释得到98个条目(P<0.05);KEGG信号通路富集分析得到42条通路(P<0.05)。结果表明，银黄可溶性粉中槲皮素、木犀草素、山奈酚和汉黄芩素可能是治疗猪喘气病的活性成分，通过作用于VEGFA、TNF等靶点，调控结核通路和哮喘通路...     

基于网络药理学预测青蒿缓解奶牛氧化应激的作用机制

运用网络药理学分析青蒿的药理成分及其作用网络，探讨其缓解奶牛氧化应激的作用机制。通过TCMSP数据库确定青蒿的化合物组成并筛选活性成分靶点，使用Uniprot找到对应靶点基因；OMIM、Gene Cards和CTD数据库查找与氧化应激(热应激)有关的病理靶点。用Venny 2.1对活性成分靶点与氧化应激疾病的靶点取交集后导入STRING数据库，建立蛋白质互作(PPI)网络并应用Cytoscape 3.9.1软件进行可视化处理及获取核心靶点。DAVID数据库对活性成分和氧化应激疾病的共同靶点基因进行GO功能注释和KEGG通路富集，应用Cytoscape软件构建成分-靶点-通路的网络图。结果表明，青蒿的化合物组成共筛选到19个活性成分及217个对应的靶点基因，氧化应激对应靶点基因共11 442个。成分与氧化应激交集靶点基因共有136个，Cytoscape筛选得到5种关键活性成分和33个关键靶点。PPI网络分析共得到11个核心靶点基因，GO功能注释细胞组分、生物学过程、分子功能各320、37、105个条目，KEGG通路富集分析得到170条通路。综上，青蒿可通过多成分、多靶点、多通路抗奶牛氧化...     

基于网络药理学和分子对接探究芪芝口服液提高家禽免疫功能的作用机制

试验旨在探究芪芝口服液提高家禽免疫功能的作用机制。采用中药系统药理学数据库与分析平台（TCMSP）收集该复方中黄芪和灵芝2味药材的活性成分及其作用靶点,并与OMIM、TTD和GeneCards数据库收集免疫的靶点进行交集,获得芪芝口服液作用于家禽免疫的潜在靶点。运用Cytoscape 3.9.1软件构建中药-成分-靶点-通路-疾病网络图和蛋白质相互作用（PPI）网络,并对靶点进行GO富集和KEGG通路分析。使用分子对接技术进行活性成分和核心靶点的分子对接验证。结果显示,芪芝口服液30个成分对应66个靶点,家禽免疫329个靶点,其中交集靶点17个,PPI核心靶点包括核因子κB抑制因子α (NFKBIA)、白细胞介素-6 (IL-6)和干扰素-γ(IFNG)等。GO功能富集共有38条结果,包括33个生物过程条目、4个分子功能条目和1个细胞成分条目;KEGG通路分析显示交集基因主要富集于C型凝集素受体信号通路、FoxO信号通路和Toll样受体等信号通路。分子对接结果显示,关键成分与核心蛋白靶点有较好的结合活性,证明了网络药理学预测结果的可靠性。研究表明,芪芝口服液可通过多成分、多靶点、多通路...     

基于网络药理学探究芪翁黄柏散治疗仔猪腹泻的有效成分及作用机制

【目的】基于网络药理学预测芪翁黄柏散治疗仔猪腹泻的有效成分，并探究其作用机制。【方法】通过TCMSP数据库筛选芪翁黄柏散潜在的有效成分和靶标蛋白，利用Cytoscape 3.9.1软件构建药物成分-靶点网络；通过GeneCards和OMIM数据库检索腹泻靶点并去重，获得疾病与药物的共同靶点，导入STRING数据库并构建蛋白互作（PPI）网络，对共同靶点进行GO功能和KEGG通路富集分析。【结果】共获得芪翁黄柏散37个有效成分和74个靶点，其中与疾病相交的共同靶点有68个；GO功能注释得到生物过程147个条目，细胞组分15个条目，分子功能32个条目；KEGG通路富集分析获得98个通路。槲皮素、山奈酚、豆甾醇、四氢小檗碱、小檗碱等为其有效成分，肿瘤坏死因子（TNF）、肿瘤蛋白P53（TP53）、血管内皮生长因子A （VEGFA）、白细胞介素6（IL6）、IL10、C-C基序趋化因子配体2（CCL2）、上皮生长因子（EGF）、核因子κB抑制剂α（NFKBIA）等为药物关键靶点，癌症、磷脂酰肌醇3-激酶/蛋白激酶B （PI3K-Akt）、丝裂原激活的蛋白激酶（MAPK）、IL17、炎症性肠病等信号通路为关键通路，还涉及到免疫应答、转录、细胞凋亡、细胞因子活性、细胞外等方面。【结论】本研究预测了芪翁黄柏散治疗仔猪腹泻的有效成分及作用机制，体现了中药多成分、多靶点、多通路的特点，并为后续研究提供方向和参考。     

基于网络药理学探究乌梅散加减方治疗猪传染性胃肠炎的作用机制

【目的】 借助网络药理学手段探究乌梅散加减方治疗猪传染性胃肠炎（TGE）的作用机制。【方法】 利用中药系统药理学数据库与分析平台（TCMSP）、Swiss TargetPrediction获取乌梅散加减方的活性成分与作用靶点，应用公共比较毒理基因组学数据库（CTD）获取TGE的相关靶点，使用STRING数据库绘制乌梅散加减方与TGE交集靶点的蛋白互作（PPI）网络图，利用DAVID对交集靶点进行GO功能和KEGG通路富集分析，探究乌梅散加减方治疗TGE的作用机制。【结果】 从乌梅散加减方中共筛选到槲皮素、山柰酚、芒柄花素等125种活性成分和JUN原癌基因（JUN）、肿瘤坏死因子（TNF）、信号传导与转录激活因子3（STAT3）等58个作用靶点。GO功能富集分析显示，共得到生物过程138个条目，涉及免疫反应、血管内皮因子生成、RNA聚合酶Ⅱ启动子对pri-miRNA转录的正调控等；细胞组分13个条目，涉及胞外区、细胞外空间、膜筏等；分子功能32个条目，涉及细胞因子活性、生长因子活性、白细胞介素2（IL2）受体活性等。KEGG通路富集分析显示，共得到135条信号通路，其中IL17信号通路、Th17细胞分化、TNF信号通路、HIF-1信号通路是乌梅散加减方治疗TGE的主要信号通路。【结论】 乌梅散加减方主要通过槲皮素、山柰酚、芒柄花素等多个活性成分调控JUN、TNF、STAT3等靶点，通过参与IL17信号通路、Th17细胞分化等治疗TGE。     

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。     

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.     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

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.     

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.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.