高锌对雏鸡免疫功能影响的研究

1日龄艾维茵肉鸡健雏200只随机分为4组，Ⅰ组(基础日粮，Zn100mg／kg)、Ⅱ组(基础日粮 Zn1400mg／kg)、Ⅲ组(基础日粮 Zn1900mg／k)和Ⅳ组(基础日粮 Zn2400mg／k)，试验期7周。病理组织学观察可见免疫器官的淋巴细胞减少，淋巴滤泡形成较少，其皮质变薄、髓质增宽并可见髓质部淋巴细胞减少。淋巴器官发育和外周血淋巴细胞的分裂增殖受抑，外周血T淋巴细胞的成熟率显著降低并引起其亚群CD4、CD8数量和组成的变化，导致机体细胞免疫和体液免疫功能的降低；雏鸡红细胞C3b受体花环率下降和免疫复合物花环率升高，引起红细胞免疫黏附功能降低。结果表明，日粮高锌可致雏鸡免疫功能受损。     

锌对雏鸭外周血T-淋巴细胞的影响

15 0只 1日龄天府肉鸭健雏随机分为 3组 ,分别喂给缺锌 (每千克日粮含 Zn 2 2 .9mg)、对照 (每千克日粮含 Zn10 0 mg)和锌中毒 (每 kg日粮含 Zn130 0 mg)日粮 7周或 4周 ,以酸性 - α-醋酸萘酯酶 (ANAE)染色法观测外周血 T-淋巴细胞的动态变化。结果锌缺乏组和锌中毒组雏鸭外周血 T-淋巴细胞的 ANAE阳性率显著低于对照组 (P<0 .0 1) ,表明锌缺乏或锌中毒可抑制 T-淋巴细胞的生成 ,降低其在外周血中的数量。本试验还对锌缺乏和锌中毒引起的外周血 T-淋巴细胞减少的机理进行了探讨     

高锌对天府肉鹅免疫功能的影响

将1日龄天府肉鹅健雏200只随机分为A、B、C、D共4组，A组作为对照组仅喂基础日粮（Zn 100mg／kg），B、C、D组分别饲喂基础日粮＋Zn900mg／kg、基础日粮＋Zn1400mg／kg和基础日粮＋Zn1900mg／kg，试验期7周，以研究高剂量锌对雏鹅免疫功能的影响。结果，与对照组相比，高锌的B、C和D组雏鹅淋巴器官发育受阻，胸腺、腔上囊和脾的器官生长指数程度不同地降低；胸腺、腔上囊和脾淋巴细胞数量减少、变性、坏死；淋巴细胞分裂增殖受抑，胸腺、腔上囊、脾和外周血淋巴细胞分裂指数程度不同地降低。结果表明，日粮高锌可致雏鹅免疫功能受损。     

铜中毒对雏鸡免疫功能影响的研究

180只1日龄艾维菌肉鸡健雏随机分为3组,分别喂以对照日粮(Cu 11.97 mg/kg)和铜中毒日粮(Cu 650 mg/kg,铜中毒Ⅰ组;Cu 850 mg/kg,铜中毒Ⅱ组)6周,观察铜中毒对免疫功能的影响.与对照组比较,两个铜中毒组雏鸡胸腺、脾脏和法氏囊的生长指数、淋巴细胞生长周期和外周血T淋巴细胞ANAE阳性率显著降低(P＜0.05或P＜0.01);病理组织学观察,淋巴免疫器官淋巴细胞显著减少并呈退性变.结果表明,铜中毒严重抑制淋巴免疫器官生长发育和外周血T淋巴细胞活化,并对淋巴免疫器官造成损伤,导致免疫功能下降.本中还就铜中毒对免疫功能的影响机理进行了讨论.     

实验性雏鸭锌中毒症的病理学研究

1日龄天府肉鸭健雏100只随机分为2组，分别喂以止常对照(Zn100mg／kg日粮)和锌中毒(Zn1300mg／kg日粮)日粮4周，进行系统的病理学研究。中毒鸭13d出现症状，18只死亡。尸检主要见腿部肌肉色白或灰白色，外观似蜡样；肌胃平滑肌色淡灰白；消化道充满黑褐色煤焦油样内容物。光镜下，骨骼肌纤维肿胀变性坏死；心肌和肌胃平滑肌局灶性坏死；胸腺、腔上囊、脾脏淋巴细胞减少。电镜观察，免疫器官淋巴细胞线粒体肿胀、嵴断裂。血液病理学变化主要是碱性磷酸酶活性、血清总蛋白与球蛋白含量以及红细胞总数和血红蛋白含量降低，血清谷丙转氨酶活性和锌含量升高。结果表明，高锌对鸭可产生明显的毒害作用。文中还对发病机理进行了探讨。     

实验性天府肉鹅锌中毒症的病理学观察

1日龄天府肉鹅健雏200只,随机分为4组,分别喂以:(1)基础日粮(Zn 100mg/kg日粮,对照组)、(2)基础日粮 Zn 900mg/kg、(3)基础日粮 Zn 1400mg/kg、(4)基础日粮 Zn 1900mg/kg,试验期7周,进行系统的病理学观察.中毒组雏鹅出现生长迟缓、拉稀、跛行等临床症状.组织学观察,肝细胞颗粒变性,骨骼肌及肌胃平滑肌变性坏死,胸腺、腔上囊和脾脏淋巴细胞数量减少、变性、坏死.血液病理学变化,主要是血清碱性磷酸酶活性下降,骨/肝碱性磷酸酶比值升高,谷丙转氨酶、肌酸激酶及淀粉酶活性程度不同地升高,血清胰岛素含量升高,仅基础日粮 Zn 1900mg/kg组49日龄降低.结果表明,高锌对鹅可产生明显的毒害作用.     

铜中毒对雏鸡淋巴细胞凋亡的影响

选用1日龄艾维菌肉鸡健雏180只，随机分为3组，分别喂以对照日（Cu 11．97mg／kg）、中毒Ⅰ日（Cu 650mg／kg）和中毒Ⅱ日粮（Cu 850mg／kg），为期6周，以流式细胞术的5r法观察研究了铜中毒对雏鸡免疫器官淋巴细胞凋亡的影响。研究结果表明，铜中毒可诱导淋巴细胞凋亡，2个中毒组免疫器官淋巴细胞凋亡百分率显著高于对照组（P〈0．05或P〈0．01）。     

铜中毒对雏鸭免疫器官细胞凋亡影响的研究

选用1日龄天府肉鸭健雏210只，随机分为3组，分别喂以对照日粮(Cu12．16mg，kg)、中毒1日粮(Cu850mg／kg)和中毒11日粮(Cu1050mg／kg)7周，以超微病理学和流式细胞术的方法观察研究了铜中毒对雏鸭免疫器官淋巴细胞凋亡的影响。电镜观察，铜中毒Ⅰ组和中毒Ⅱ组免疫器官淋巴细胞发生凋亡的频率明显高于对照组。发生凋亡的淋巴细胞表现为染色质凝聚、边集、细胞核呈新月形、“C”形、花瓣状、圆环状或圆斑状，并出现凋亡小体。流式细胞术测定．2个中毒组免疫器官淋巴细胞凋亡百分率也明显高于对照组。上述研究结果表明．铜中毒可以诱导淋巴细胞凋亡。     

实验性雏鸡铜中毒的病理学研究

选用1日龄艾维菌肉鸡180只随机分为3组，分别以对照日粮（Cu 11．97mg／kg）、铜中毒Ⅰ组日粮（Cu 650mg／kg）和铜中毒Ⅱ组日粮（Cu 850mg／kg）饲喂6周，以实验病理学方法系统研究了铜中毒对雏鸡组织器官和某些血液指标的影响。2个铜中毒组在试验的第2、3周先后出现临床症状；铜中毒Ⅱ组雏鸡的发病率和死亡率高于铜中毒Ⅰ组。病理形态学观察，2个铜中毒组的病变基本一致，表现为肌胃角质层增厚、龟裂，肠绒毛裸露断裂，伴有坏死；肝细胞脂肪变性；肾小管上皮细胞变性，坏死脱落；淋巴免疫器官体积缩小、重量减轻、淋巴细胞数量减少。2个铜中毒组雏鸡血清谷草转氨酶（AST）活性显著升高，红细胞数量、血红蛋白含量显著降低（P〈0．05或P〈0．01）。表明，雏鸡在生长发育的2～6周对高剂量铜较为敏感，毒性损坏的靶器官是肝、肾、胃肠道和淋巴免疫器官，铜中毒导致雏鸡组织器官受损、功能障碍及免疫功能低下，最终导致发病、死亡。     

高铜对雏鸡外周血T-淋巴细胞ANAE阳性率的影响

选用1日龄艾维菌健康肉鸡420只,随机分为7组,分别喂以对照日粮(Cu 11 mg/kg)和高铜日粮(Cu 100mg/kg),高铜Ⅰ组,Cu 200 mg/kg,高铜Ⅱ组;Cu 300 mg/kg,高铜Ⅲ组;Cu 400 mg/kg,高铜Ⅳ组,Cu 500 mg/kg,高铜Ⅴ组;Cu 600 mg/kg,高铜Ⅵ组)6周,观察日粮铜添加水平对雏鸡外周血T-淋巴细胞ANAE阳性率的影响.与对照组比较,高铜Ⅰ、Ⅱ组雏鸡外周血T-淋巴细胞ANAE阳性率增加,但差异不显著;高铜Ⅲ、Ⅳ、Ⅴ、Ⅵ组雏鸡外周血T-淋巴细胞ANAE阳性率降低,且与日粮含铜量呈负相关,同时胸腺淋巴细胞减少,凋亡细胞比例增高.结果表明,与对照组比较,日粮铜含量100～200 mg/kg对雏鸡外周血中T-淋巴细胞ANAE阳性率有促进作用,但差异不显著;日粮铜含量300～600 mg/kg程度不同地降低了T-淋巴细胞ANAE阳性率,细胞免疫功能受损.     

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.     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -     

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.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein