共查询到19条相似文献，搜索用时 78 毫秒
1.
应用组织切片技术对11～53日龄吉林白鹅小肠绒毛高度、绒毛宽度、隐窝深度和肌层厚度进行测定。结果显示,小肠各段绒毛高度及宽度随日龄增加整体上呈增长趋势,空肠绒毛最长,回肠绒毛高度、宽度在39日龄达到峰值,早于空肠和十二指肠。回肠隐窝深度11～53日龄随日龄增加而增加,十二指肠和空肠隐窝深度在39日龄达到峰值,39～53日龄变浅。小肠各段肌层厚度与日龄呈正相关,回肠的肌层厚度在46日龄达到高峰,十二指肠和空肠的肌层厚度在53日龄达到高峰。小肠各段绒毛高度/隐窝深度的比值随日龄增加而增加,53日龄时空肠的绒毛高度/隐窝深度的比值最高。 相似文献
2.
试验旨在研究氨基酸转运载体相关基因在番鸭小肠不同肠段的表达规律。试验测定90和300日龄公番鸭体重与小肠形态发育,采用RT-PCR比较氨基酸转运载体相关基因SLC1A1、SLC1A4、SLC7A1、SLC7A5和SLC7A9在90和300日龄公番鸭小肠不同肠段的表达量,并进行高、低体重组300日龄公番鸭回肠氨基酸转运载体相关基因表达的验证试验。结果显示：除回肠绒毛高度外,300日龄番鸭十二指肠、空肠和回肠的肠壁厚度、隐窝深度和绒毛宽度以及十二指肠和空肠的绒毛高度均显著高于90日龄（P<0.05）;300日龄番鸭空肠和回肠的肠壁厚度显著高于十二指肠（P<0.05）,90、300日龄番鸭十二指肠的绒毛高度和隐窝深度显著高于空肠和回肠（P<0.05）;300日龄番鸭十二指肠和空肠SLC1A1 mRNA表达量、十二指肠和回肠SLC7A5 mRNA表达量以及十二指肠、空肠和回肠SLC7A9 mRNA表达量均显著高于90日龄（P<0.05）;300日龄番鸭回肠SLC1A1、SLC1A4、SLC7A5和SLC7A9 mRNA表达量显著高于空肠和十二指肠（P<0.05）;... 相似文献
3.
补料日龄对哺乳期仔猪小肠黏膜形态的影响 总被引：1，自引：0，他引：1
为研究补料日龄对哺乳期仔猪小肠绒毛形态的影响。试验采用单因素完全随机试验设计,选取母猪分娩时间相差在48 h之内、泌乳性能良好、产仔数接近的12窝仔猪,分4个处理组,每组3个重复,分别于仔猪出生后7、10、15日龄和21日龄开始补料。结果表明:28日龄断奶时,7日龄与10日龄补料组仔猪十二指肠、空肠前段和空肠后段部位小肠绒毛高度显著高于其他两组(P<0.05),10日龄补料组回肠部位绒毛高度最高(P<0.05)。7日龄与10日龄补料组仔猪十二指肠、空肠前段隐窝深度显著低于15日龄与21日龄补料组(P<0.05),而空肠后段和回肠部位的隐窝深度以10日龄最低(P<0.05)。除十二指肠外,补料日龄对小肠不同部位肠壁厚度没有显著影响。因此,仔猪出生后10日龄补料对断奶时仔猪小肠绒毛形态影响最小。 相似文献
4.
膨化与加酶玉米对断奶仔猪生长性能和肠黏膜形态的影响 总被引：1，自引：0，他引：1
通过2个饲养试验，研究了膨化及加酶处理玉米对断奶仔猪的生长性能和肠黏膜形态的影响。试验一分别用普通玉米、膨化玉米、普通玉米加酶及膨化玉米加酶为主要能量原料的饲料饲喂仔猪做4种处理，每个处理6个重复，定时记录体质量和耗料量．计算日增重、日采食量和料肉比。结果表明，膨化和加酶玉米均可提高日增重，降低料肉比。试验二分别用普通玉米、膨化玉米、普通玉米加酶及膨化玉米加酶为主要能量原料的饲料饲喂仔猪做4种处理，每个处理6个重复，分别在断奶后第14天和第28天各屠宰1头公猪。取十二指肠、空肠前、中、后段以及回肠做组织切片，观察其黏膜厚度、绒毛高度、隐窝深度和绒毛宽度。结果表明，断奶后14d，与普通玉米组相比，膨化玉米组和加酶玉米组都显著提高了十二指肠的绒毛高度，二者共同处理组使十二指肠的绒毛高度极显著提高；2种处理组都显著降低了空肠中段的隐窝深度；显著增加了十二指肠、空肠前段、后段和回肠的黏膜厚度。断奶后28d，2种处理组都显著增加了十二指肠的黏膜厚度。 相似文献
5.
羔羊不同断奶日龄对小肠黏膜形态的影响 总被引：2，自引：0，他引：2
为了探索不同断奶日龄对羔羊小肠黏膜形态的影响,试验分别选取15、30和45日龄波尔山羊(♂)×南江黄羊(♀)杂交一代断奶羔羊各10只,分为3个试验组;同时选15日龄羔羊14只,自然断奶作为对照组。各试验组断奶后10 d(对照组分别在25、40和55日龄),空腹屠宰取十二指肠、空肠、回肠中部各2 cm作组织切片,观察其绒毛高度、隐窝深度和绒毛形态结构。结果表明:与对照组相比,各断奶组羔羊十二指肠、空肠和回肠的绒毛高度、隐窝深度和绒毛形态均有不同程度的变化。断奶日龄越早,羔羊小肠黏膜变化越明显,其中绒毛高度下降幅度越大,隐窝深度加深越严重,断奶10 d后恢复情况越差,断奶日龄推迟到30日龄时损伤较小,恢复较好。羔羊30日龄断奶饲喂代乳料,对其小肠形态结构影响较小,实施断奶最好。 相似文献
6.
试验旨在探索对仔猪床进行加温处理以及采用定时饲喂的方式的对早期断奶仔猪不同肠段黏膜形态和肠道发育的影响,从而为确定断奶仔猪适宜的饲养温度和科学的饲喂方式提供理论依据。试验采用2×2因子设计。选用21日龄杜长大断奶仔猪240头,随机分到4个处理组:1):28~30℃的仔猪床加温处理组;2)23~25℃的低温对照组(炉火暖气管道舍内加热);加温处理组和低温对照组中又根据不同的饲喂模式分为每天6次定时饲喂组和自由采食组。每个处理6个重复,每个重复10头猪。经过14 d的试验之后,在每圈仔猪中随机抽取1头,屠宰后取样检测小肠黏膜的绒毛高度、隐窝深度和肠壁厚度。结果表明:加温饲养组(28~30℃)的仔猪空肠中段的绒毛高度显著高于低温对照组(23~25℃)(P<0.05)。加温饲养组十二指肠的隐窝深度和空肠中段的肠壁厚度显著低于低温对照组(P<0.05)。定时饲喂饲养的仔猪空肠后段的绒毛高度显著高于自由采食饲养的仔猪(P<0.05)。定时饲喂组仔猪空肠中段的肠壁厚度和十二指肠隐窝深度显著低于自由采食组(P<0.05)。2因子的互作效应表明:加温定时饲喂组饲养的仔猪空肠后段的绒毛高度显著高于其他处理组。低温自由采食组饲养的仔猪空肠后段的绒毛高度极显著低于其他处理组(P<0.01)。加温定时饲喂组的仔猪空肠中段的肠壁厚度极显著低于其他处理组(P<0.01)。由结果可知,28~30℃的加温饲养组以及定时饲喂的饲喂模式有利于仔猪的肠道黏膜形态的改善,有益于肠道的发育和健康。 相似文献
7.
21日龄断奶对仔猪肠道形态、肠道通透性及肠黏膜屏障的影响 总被引：2，自引：0，他引：2
本试验旨在研究21日龄断奶对仔猪肠道形态、肠道通透性及肠黏膜屏障的影响。采用2×3双因子完全随机试验设计,组别(哺乳组、断奶组)和日龄(22、24和28日龄)为2个主效应。选取6窝体况相近的健康大白仔猪,每窝选取6头平均体重为(6.1±0.2)kg的仔猪,随机分为2组,分别为断奶组和哺乳组,每组18头,分别于22、24和28日龄时屠宰,测定其生长性能、肠道形态、肠道通透性及肠黏膜屏障。结果表明:1)28日龄时,断奶组仔猪的末重和平均日增重均极显著低于哺乳组(P0.01)。2)组别和日龄对仔猪的空肠隐窝深度和绒毛高度/隐窝深度、回肠绒毛高度有极显著交互作用(P0.01);断奶组的空肠、回肠隐窝深度极显著高于哺乳组(P0.01),空肠、回肠绒毛高度和绒毛高度/隐窝深度极显著低于哺乳组(P0.01);哺乳组28日龄时的空肠绒毛高度/隐窝深度极显著高于22和24日龄时(P0.01),24日龄时的回肠绒毛高度极显著高于22日龄时(P0.01)。3)组别和日龄对仔猪的空肠黏膜二胺氧化酶(DAO)活性有显著交互作用(P0.05),断奶组的空肠、回肠黏膜DAO活性显著低于哺乳组(P0.05)。4)组别和日龄对仔猪空肠黏膜闭锁蛋白(occludin)的mRNA表达量有极显著交互作用(P0.01);空肠黏膜闭锁小带蛋白1(ZO-1)和哺乳组空肠黏膜occludin的mRNA表达量随着日龄的增加先升高后降低(P0.05);与哺乳组相比,断奶组回肠黏膜ZO-1、occludin和24日龄时空肠黏膜occludin的mRNA表达量显著降低(P0.05);24日龄时回肠黏膜ZO-1的mRNA表达量显著高于22日龄时(P0.05)。5)组别和日龄对仔猪空肠黏膜肿瘤坏死因子α(TNF-α)的mRNA表达量有显著交互作用(P0.05);断奶组24和28日龄时空肠黏膜TNF-α的mRNA表达量显著高于哺乳组(P0.05),空肠黏膜白细胞介素10(IL-10)的mRNA表达量显著低于哺乳组(P0.05)。回肠黏膜白细胞介素1β(IL-1β)的mRNA表达量随着日龄的增加而降低(P0.05)。综上所述,哺乳仔猪22~28日龄时肠道发育趋于成熟,而断奶会破坏仔猪肠道上皮细胞的结构和紧密连接蛋白的mRNA表达,引起肠道绒毛变短和脱落、肠道通透性增加和炎症反应,降低平均日增重。 相似文献
8.
谷氨酰胺和牛磺酸对仔猪肠黏膜形态的影响 总被引：1，自引：0，他引：1
甘氨酰谷氨酰胺( Gly-Gln)和牛磺酸(Tau)对早期断奶仔猪小肠各段黏肠DNA和形态的影响.以28日龄杜×长×大断奶仔猪为研究对象,通过饲养和屠宰试验,研究Gly-Gln和Tau对早期断奶仔猪十二指肠、空肠和回肠黏肠DNA及形态的影响.结果表明:饲粮中分别或同时添加Gly-Gln和Tau均可提高小肠各段黏膜DNA的含量.Gly-Gln组能显著提高空肠和回肠段的黏膜DNA含量,Tau组和复配组对小肠各段黏膜DNA含量影响不显著;Gly-Gln组极显著增加了十二指肠和回肠的黏膜厚度(MT),显著提高了十二指肠和回肠后段的绒毛高度(VH),显著或极显著降低了空肠前段和中段的隐窝深度(CD),极显著提高了空肠前段和中段的VH/CD,显著提高了回肠段的VH/CD;Tau组极显著提高了十二指肠段的VH并降低了CD,极显著提高了十二指肠段和空肠中段的VH/CD;复配组显著或极显著降低了十二指肠段和空肠中段的CD,极显著提高了空肠前段、中段和回肠段的VH/CD.这说明,在早期断奶仔猪饲粮中分别或同时添加0.25%Gly-Gln和0.1% Tau能有效提高仔猪肠黏膜的发育及功能. 相似文献
9.
文章旨在研究用5%花椒籽替代基础饲粮中玉米,对生长育肥猪小肠组织形态的影响,探究花椒籽作为新型饲料来源对育肥猪生长发育的影响。试验选取144头90日龄、体重33 kg的健康杜×长×大杂交猪,随机分为2组,每组72头猪,以饲喂添加5%花椒籽替代基础饲粮中玉米作为试验组,以饲喂基础饲粮为对照组,试验结束后,采集对照组和试验组的生长育肥猪的小肠组织（十二指肠、空肠和回肠）放置于10%多聚甲醛液中固定,对两组生长育肥猪的十二指肠、空肠和回肠的组织进行苏木精-伊红染色（HE染色）并测量分析,分别检测了猪只各小肠组织（回肠、空肠和十二指肠）的绒毛高度、隐窝深度、绒毛宽度和肠壁厚度四个指标,对其进行SPSS单因素分析和独立样本t检验分析,结果表明：花椒籽可以显著增加回肠和空肠的绒毛高度和绒毛宽度（P<0.05）,降低隐窝深度,从而增强生长育肥猪的消化吸收能力,促进其生长发育。 相似文献
10.
谷氨酰胺对早期断奶仔猪生长性能及肠道形态发育的影响 总被引：1，自引：0，他引：1
选21日龄断奶的杜大长仔猪72头,按试验要求分为2组,每组3个重复,每重复12头。分别饲喂基础日粮和含1%谷氨酰胺(Gln)日粮,试验期21 d,在断奶后0 d、7 d和14 d分别屠宰取小肠测重,并取十二指肠、空肠、回肠测定绒毛高度和隐窝深度。试验结果表明:断奶后7 d,日粮中添加Gln可显著提高仔猪的平均日增重和小肠相对重量,提高十二指肠和空肠绒毛的高度,降低十二指肠和空肠的隐窝深度;断奶后14 d,日粮中添加Gln对断奶仔猪的生长和肠道形态发育影响与基础日粮组相比差异不显著。 相似文献
11.
M.C. Marinho M.A. Pinho R.D. Mascarenhas F.C. Silva M.M. Lordelo L.F. Cunha J.P.B. Freire 《Livestock Science》2007,108(1-3):240-243
Forty eight 21 days old piglets were used to compare the effect of prebiotic or probiotic supplementation and ileo rectal anastomosis on the morphology of the small intestine. Half of the piglets were maintained intact and the other half was subjected to an ileo rectal anastomosis (IRA). Each group of piglets received one of the following diets: 1) basal diet (C), 2) basal diet supplemented with a Xylo-oligosaccharide (XOS), 3) basal diet supplemented with a Saccharomyces cerevisiae (SC) and 4) basal diet supplemented with XOS and SC. Villus height was greatest with XOS and with XOS + SC, only in the ileum, as compared to controls. In the duodenum, crypt width was highest in the control group, but no significant differences were found in the jejunum and ileum. The IRA piglets had longer villi in the jejunum and shorter villi in the ileum. The crypt depth was greater in the duodenum and in the ileum of IRA piglets. Villus height/crypt depth was lower in the duodenum and in the ileum, in the IRA piglets. In conclusion, the XOS, but not the SC, moderately modified the intestinal morphology. The IRA modified the intestinal villus and crypt architecture but its consequence on the absorption of nutrients needs to be investigated. 相似文献
12.
试验旨在研究基础日粮中添加植物乳杆菌(Lactobacillus Plantarum)WEI-70菌粉对产蛋鸡的生产性能、蛋品质、组织病理学影响,评价菌株WEI-70对产蛋鸡的安全性和功效性。试验使用305日龄海兰褐蛋鸡288只,随机分为2组,每组设6个重复,每个重复24只鸡,对照组饲喂基础日粮,试验组在基础日粮中添加植物乳杆菌WEI-70冻干菌粉,每克日粮中的活菌浓度为1×10~6 CFU。结果表明:与对照组相比,试验组的平均日产蛋量显著提高了2.71%(P0.05),平均料蛋比显著下降了3.27%(P0.05),哈氏单位显著提高了3.42%(P0.05),蛋黄颜色显著提高了4.37%(P0.05);试验组和对照组的心、肝、脾的脏器重量和脏器指数均无显著差异(P0.05),都没有出现病理学变化,但与对照组相比,试验组的空肠绒毛高度显著提高了31.82%(P0.05)。由此可见,植物乳杆菌WEI-70在蛋鸡养殖生产中能够促进蛋鸡生产性能、蛋品质的提升和空肠绒毛高度增加,并且不会引起脏器的病理变化,体现出较高的安全性。 相似文献
13.
异麦芽寡糖对肉仔鸡生产性能及肠道生理生化指标的影响 总被引：11，自引：1，他引：10
试验选用 90 0只雌雄各半 1日龄艾维茵肉鸡分 6组 ,每组 3重复 ,分别在饲料中添加异麦芽寡糖 (IOS) 0 %、0 .1%、0 .2 %和 0 .4 %、金霉素 15 0mg kg及金霉素 15 0mg kg+0 .4 %IOS ,研究了ISO对肉鸡的生产性能及肠道生理和生化指标的影响。IOS和金霉素处理均促进 0～ 3周肉鸡的采食 (P <0 .0 5 ) ,且IOS促进肉鸡采食的作用随添加量的提高而增强。IOS和金霉素处理降低 3周龄肉鸡回肠内容物中挥发性盐基氮含量 (P <0 .0 5 )和盲肠内容物中丙酸含量 (P <0 .0 1)。IOS处理增加 3周龄肉鸡空肠绒毛长度 (P <0 .0 1)。与添加 15 0mg kg金霉素组比较 ,IOS处理提高 3周龄肉鸡盲肠中丁酸含量 (P <0 .0 5 )和空肠绒毛长度 (P <0 .0 1) ,对其它各指标无影响。 相似文献
14.
苜蓿草粉对黄河鲤鱼消化生理指标的影响 总被引：1，自引：0，他引：1
选取来源一致、体质健康、尾均重为248.70±1.31 g的黄河鲤鱼750尾,采用单因子完全随机设计,设5个处理,3个重复,分别在基础饲粮中添加0%(对照组)、5%(试验Ⅰ组)、10%(试验Ⅱ组)、15%(试验Ⅲ组)和20%(试验Ⅳ组)紫花苜蓿草粉,研究其对黄河鲤鱼消化生理指标的影响。结果表明:1)苜蓿草粉的添加对黄河鲤鱼消化道指数无显著影响(P>0.05)。2)肝胰脏和前、中、后各肠段的蛋白酶和淀粉酶活性均随着苜蓿草粉的添加比例的增加呈现先升后降的趋势。其中,5%和10%的苜蓿草粉添加组在肝胰脏和后肠中的蛋白酶活性显著高于对照组(P<0.05);5%和10%添加组在肝胰脏和各个肠段的淀粉酶活性均显著高于对照组(P<0.05);3)适宜水平的苜蓿草粉(5%、10%)能够提高黄河鲤鱼肠绒毛高度,在前肠,10%添加组的肠绒毛高度显著高于对照组(P<0.05);而高含量的苜蓿草粉(15%、20%)则降低了肠绒毛高度。综合表明,在黄河鲤鱼饲粮中添加10%苜蓿草粉能显著提高其消化酶活性及肠绒毛高度。 相似文献
15.
Rassnick KM Gieger TL Williams LE Ruslander DM Northrup NC Kristal O Myers NC Moore AS 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2001,15(3):196-199
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. 相似文献
16.
Davis MS Willard MD Nelson SL Mandsager RE McKiernan BS Mansell JK Lehenbauer TW 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(3):311-314
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. 相似文献
17.
Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects 总被引：1，自引：0，他引：1
Johansson AM Gardner SY Levine JF Papich MG LaFevers DH Fuquay LR Reagan VH Atkins CE 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(6):887-895
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. 相似文献
18.
Tropical Animal Health and Production - 相似文献
19.
Waruiru RM Thamsborg SM Nansen P Kyvsgaard NC Bogh HO Munyua WK Gathuma JM 《Tropical animal health and production》2001,33(3):173-187
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. 相似文献