Effect of dietary formic and propionic acids on salmonella pullorum shedding and mortality in layer chicks after experimental infection

This investigation was conducted to study the effect of dietary formic acid (FA) and propionic acid (PA) mixture on inhibitory effect of Salmonella pullorum in layer chicks. Nine equal groups of 1-day-old layer chicks, in addition to positive and negative controls, were fed on day 3 of age with acid-treated feed containing mixture of both acids at concentrations, from 0.5 to 1.5%. Positive and negative controls were fed untreated feed. All groups except the negative control were challenged orally on day 3 with 104 CFU/ml/bird S. pullorum. Cloacal swabs were taken at three successive days and at 7, 14 and 21 days of challenge. After 1, 2 and 3 weeks after challenge, four chicks from each group were killed, and crop and caecal contents were examined for S. pullorum and pH. The numbers of S. pullorum re-isolation from all treated groups, 'except groups treated with mixture of 0.5% and 0.5%, 1% and 0.5% as well as 0.5% and 1% FA and PA', decreased significantly (P < 0.05) compared with the positive control. The mortality rates of all treated groups except the group treated with 0.5% FA and 0.5% PA decreased significantly (P < 0.05) compared with the positive control. The treatment significantly (P < 0.05) lowered the pH of the crop and caecal contents in all groups except the group treated with 0.5% FA and 0.5% PA compared with the control. Also, the treatment significantly (P < 0.05) lowered the pH of the crop and caecal contents in all groups after 3 weeks of treatment compared with the first and second weeks. The treatments significantly (P < 0.05) lowered the frequency of S. pullorum recovery from crop and caecal contents in six groups treated with 1.5 and 0.5, 1 and 1, 1.5 and 1, 0.5 and 1.5, 1 and 1.5, 1.5% and 1.5% FA and PA, respectively. These results indicate that addition of FA and PA mixture in a total concentration of 2% or more to the diet of newly hatched infected layer chicks significantly decreases the crop and caecal colonization by S. pullorum and significantly decreases S. pullorum faecal excretion and reduced the chick mortality rate.     

雏痢净对人工感染雏鸡白痢的疗效观察

雏鸡白痢是由鸡白痢沙门氏菌引起的鸡和火鸡等禽类的传染病。雏鸡患病呈急性败血性经过，以白痢为主要症状，在成鸡多呈慢性经过或无症状感染。雏鸡白痢一般发生在3周龄内的雏鸡，发病率和死亡率都较高，是阻碍养鸡业发展的重要疾病之一。雏痢净是一种纯中药复方制剂，主要用于防治雏鸡白痢，为了客观评价其对雏鸡白痢的防治效果，特组织进行了本次雏鸡人工感染鸡白痢沙门氏菌病的治疗试验，报道如下。     

"雏痢净"对人工感染雏鸡白痢的疗效研究

对人工感染鸡白痢的艾维茵雏鸡采用"雏痢净"按高(0.5 g/只)、中(0.4 g/只)、低(0.3 g/只)三个剂量混饲治疗,用2%甲磺酸培氟沙星(药物对照)组、感染不用药(阳性对照)组、不感染不用药(阴性对照)组作为对照.结果:"雏痢净"高、中、低剂量组与2%甲磺酸培氟沙星组对雏鸡白痢均有较高的疗效,其中"雏痢净"高、中剂量组与2%甲磺酸培氟沙星组的治疗效果最好,但三者差异不显著(P＞0.05);"雏痢净"各组与2%甲磺酸培氟沙星组的相对增重率极显著高于感染不用药组(P＜0.01).研究表明,"雏痢净"高、中剂量组雏鸡用药后症状明显减轻且渐恢复,体重也明显增加,其疗效与2%甲磺酸培氟沙星相当.     

Role of glycoconjugates in adherence of Salmonella pullorum to the intestinal epithelium of chicks

1. The distribution of glycoconjugates on the surface of Salmonella pullorum and the ileal epithelium of chicks was demonstrated by lectin cytochemistry. The role of glycoconjugates in adherence of S. pullorum to the ileal epithelium was determined by a sugar inhibition assay using the scanning electron microscope.

2. S. pullorum exhibited binding to Concanavalin A (Con A) and wheat germ agglutinin (WGA) but not to soyabean agglutinin (SBA), Ricinus communis agglutinin (RCA) and Ulex europaeus agglutinin (UEA).

3. The ileal epithelium of chicks bound WGA, Con A and SBA. The binding sites for WGA were on the brush border and cytoplasm of columnar enterocytes as well as on goblet cells. The binding of Con A was confined to the cytoplasm of columnar enterocytes, while SBA bound, in a limited way, to the brush border of columnar enterocytes.

4. After an oral dose of S. pullorum, adherence to the ileal epithelium was inhibited by methyl α‐D‐mannopyranoside.     

Pathology of experimental chlamydiosis in chicks

Twelve one-day-old chicks were experimentally inoculated with Chlamydia psittaci derived from turkeys. Acute chlamydial septicemic lesions were induced by the inoculation into the air sac and trachea. No lesions were produced by the esophageal injection. Clinically, the affected chicks showed emaciation and mouth breathing, and were inactive while some birds died. Grossly, they had hepatomegaly, splenomegaly and airsacculitis. Histopathologically, fibrinopurulent airsacculitis, pneumonia and bronchitis, multiple fibrinous serositis in the hepatic and splenic capsules, peri- and epicardium, and mesenterium, focal endoarteritis in the aortae, activation of reticuloendothelial cells in the spleen, and hepatic necrosis were noted. Immunohistochemically, chlamydial antigen granules were present in the cytoplasm of epithelial cells of the respiratory system, hepatocytes, macrophages in the air sac, lung, serous membrane, liver, spleen, aortae, reticuloendothelial cells in the spleen, and mesothelial cells in various organs or tissues. Chlamydial multiplication in the cells of the organs or tissues involved was preceded to form the lesions.     

种鸡场鸡白痢病的综合防治

鸡白痢是由鸡白痢沙门氏杆菌引起的鸡和火鸡等禽类的传染病。要防治本病,必须从种鸡抓起,有计划地进行鸡白痢检疫,淘汰阳性鸡,切断横向传播和垂直传播途径,结合综合防治措施,有效控制此病的发生。1种蛋消毒1.1种鸡场要建立严格的种蛋消毒措施。每栋种鸡舍要设种蛋消毒柜,饲养员必须按规定每2h集蛋一次,然后检出脏蛋、破蛋、畸形蛋后,将种蛋大头向上码放在蛋盘里,放入种蛋消毒柜,用28ml/m3福尔马林熏蒸30min。1.2种蛋送入孵化厅后,按上述方法再次消毒后,或入孵,或送种蛋库保存,保存时间不要超过一周。特别在炎热的夏季,种蛋要低温(18～25℃)…     

甲硝唑对鸡马立克氏病疫苗免疫作用影响的观察

选1日龄雏鸡,肌肉注射火鸡疱疹病毒(HVT)冻干疫苗,随机分为4组,每组20只.1组和2组鸡免疫同时分别应用10、100毫克/千克体重·天甲硝唑,3组免疫同时应用10毫克/千克体重·天左旋咪唑,连用3天,4组为空白对照组.采集外周血淋巴细胞和血清,应用淋巴细胞转化试验和酶联免疫吸附试验(ELISA)测定T淋巴细胞转化和抗HVT抗体滴度.结果表明,10和100毫克/千克体重·天甲硝唑用药鸡外周血T淋巴细胞转化和鸡血清抗HVT抗体滴度均比空白对照组明显升高;10毫克/千克体重·天左旋咪唑用药后也具有类似作用.     

黄芩提取物治疗肉仔鸡白痢试验

1 材料与方法 1．1 鸡白痢沙门氏菌标准血清、鸡白痢沙门氏菌标准抗原(作对照用)由山东省兽医总站化验中心购进。