鸡坏死性肠炎生物性防控研究进展

鸡坏死性肠炎(necrotic enteritis,NE)是现代化肉鸡集约养殖生产中最为突出的肠道疾病之一,给家禽产业带来了巨大的经济损失。随着世界范围内的立法限制、禁用抗生素生长促进剂,鸡坏死性肠炎的发病率在全球范围内呈上升趋势,这对家禽的生产和健康产生严重威胁。因此,迫切需要新的技术和新的产品代替抗生素来预防和控制鸡坏死性肠炎。作者着眼于NE的危害和疫苗、噬菌体、卵黄抗体、植物提取物、酸化剂、益生菌、低聚糖与微生物多糖等生物性防控进展,综述了目前有效预防和控制鸡坏死性肠炎的生物性措施的最新研究情况,既为鸡坏死性肠炎生物性防控提供技术参考,也为其深入研究提供了理论思考。     

鸡坏死性肠炎的诊治

1 发病情况 2007年6月20日格尔木市某鸡场突然发生5～6周龄的育成鸡不明原因的死亡,死前没有明显症状,只见拉黑色稀粪.     

鸡坏死性肠炎的病例

我们对沈阳市郊某蛋鸡场的青年鸡舍所发生的以小肠下部及盲肠充满气体,肠壁充血、出血、坏死及肝火面积坏死为主要特征的疾病,通过现场及实验室诊断,疑为产气荚膜杆菌引起鸡坏死性肠炎,报告如下。     

鸡坏死性肠炎及其防治

鸡坏死性肠炎是由产气荚膜杆菌(Clastridium Perfringens,C.P)引起的鸡的一种急性细菌性传染病,主要发生在11周龄以下的幼鸡,多发生于2～8周龄,特别是3周龄以下的鸡。以发病突然、急性死亡为特征。本病最早Parish(1961)发现与英国,目前欧洲、澳大利亚、美国、加拿大、斯里兰卡、日本及我国等世界各地均有大批发生或零散发生。欧美等一些国家和地区已将本病列为肉食鸡的重要疾病之一,并给予高度重视。 1 病因 关于鸡坏死性肠炎,许多研究者都报道过野外病例     

鸡坏死性肠炎的防控思路

该文介绍鸡坏死性肠炎发病原因、用药防控现状、药效不明显的原因以及防控思路。     

一起鸡坏死性肠炎的诊治

鸡坏死性肠炎是一种急性消化道传染病,该病在养鸡生产中发生较多,常给养鸡业带来经济损失。以一起河北省涞水县某养殖场发生的鸡坏死性肠炎为例,对该病的临床症状、病理变化、诊断方法及防治措施作一介绍,以期为有效防控该病提供参考。     

一起鸡坏死性肠炎的诊治

鸡坏死性肠炎是一种急性消化道传染病,该病在养鸡生产中发生较多,常给养鸡业带来经济损失。以一起河北省涞水县某养殖场发生的鸡坏死性肠炎为例,对该病的临床症状、病理变化、诊断方法及防治措施作一介绍,以期为有效防控该病提供参考。     

鸡梭菌性肠炎研究概论

从病原学、流行病学、症状及病变、致病机理、诊断、治疗及预防、免疫进展等方面对鸡梭菌性肠炎进行介绍,并对该病未来研究热点进行了展望,为开展鸡梭菌性肠炎的基础研究、疾病预防控制提供参考。     

Use of Bacitracin and Roxarsone to Reduce Salmonella Heidelberg Shedding Following a Necrotic Enteritis Challenge Model

This study was performed to determine if the enteric disease necrotic enteritis results in higher shedding of Salmonella. Fifty percent of the chicks per pen were challenged with a naladixic acid-resistant Salmonella Heidelberg. A necrotic enteritis challenge model using a coccidia vaccine to induce intestinal epithelium damage was used to demonstrate that neither the disease necrotic enteritis nor the control of that disease with the antibiotic bacitracin methylene disalycilate had an effect on the incidence of Salmonella Heidelberg. However, the feed additive 3-nitro-4-hydroxyphenylarsonic acid, which controls the cecal coccidia Eimeria tenella, significantly reduced the amount of Salmonella Heidelberg in the environment of the chick as measured by dragswabs and also reduced the number of ceca positive in the contact chicks.     

Research Progress on Prevention and Treatment of Necrotic Enteritis in Livestock

Necrotic enteritis is an acute gastrointestinal infectious disease with high morbidity and mortality which caused by Clostridium perfringens. The disease not only harms the livestock health and animal welfare,but also has been an emerging threat for breeding industry and human health. Antibacterial drugs played a positive role on preventing this disease,however,drug-resistant strains were increasing with irrational use of antibiotics,the incidence of necrotic enteritis has drastically increased, prevention and treatment of it faced severe challenges. The author reviewed the characteristics of necrotic enteritis include the etiology,physicochemical properties, epidemiology and clinical signs,at the same time, the control measures and common drugs were summarized,and the new development trend and direction for prevention and treatment necrotic enteritis was objective analyzed, aiming to establish a comprehensive understanding of the disease,provide references for prevention and treatment of the disease.     

畜禽坏死性肠炎防制研究进展

畜禽坏死性肠炎主要是由产气荚膜梭菌引起的一种急性消化道传染病,具有较高的发病率和死亡率。该病不仅损害畜禽健康,影响动物福利,而且对养殖业发展及人类健康造成了严重威胁。抗菌药的出现对该病起到了积极限制的作用,然而随着抗菌药的不合理使用,耐药菌株不断增加,坏死性肠炎的发病率呈现升高的趋势,防制坏死性肠炎面临严峻挑战。作者从坏死性肠炎的特征入手,综述了坏死性肠炎的病原学、理化特性、流行病学、临床症状等,与此同时对坏死性肠炎的防制措施及目前常用药物进行了总结,客观分析了防制坏死性肠炎的趋势与发展方向,旨在健全对该病的认识,为坏死性肠炎的防制研究提供参考。     

Necrotic enteritis: Applications for the poultry industry

Considering market demands concerning the decreased use of growth promoters and anticoccidial drugs in feed formulations, the poultry industry has been trying to reduce or eliminate the inclusion of subtherapeutic doses of antimicrobials into feed. Formulating diets not only to meet birds’ nutrient requirements for growth but also for gastrointestinal health parameters is increasingly important. Maintenance and enhancement of intestinal integrity is essential for bird performance when antimicrobials are not included in feed, as commercial poultry face numerous enteric pathogen challenges. Necrotic enteritis has reemerged as an important disease of poultry in recent years. The reduction in the use of antimicrobials in poultry feeds has been attributed as one of the main contributing factors for the increasing incidence of necrotic enteritis (NE) in commercial poultry. Mortality due to NE is extremely high (1% daily mortality), which results in great economic losses. Economic losses due to NE are not only associated with high mortality, but also associated with decreases in bird performance and FE, particularly in subclinical cases of NE. Birds that survive NE outbreaks usually have a reduced ability to digest and absorb nutrients due to extensive damage to the mucosal lining, which ultimately results in reduced profitability.     

Necrotic Enteritis in Broiler Chickens II. Pathology and Proposed Pathogenesis

The intestines from 124 dead, sick and normal broiler chickens from 24 cases of necrotic enteritis were subjected to histological examination. Tissue sections from the duodenum, jejunum, ileum and ceca from each broiler were examined histologically for lesions of necrotic enteritis and the presence of coccidia. Lesions of necrotic enteritis were present in one or more areas of the intestine in all but six of 94 dead or sick birds and they were most common and severe in the jejunum. Coccidia were found in only small numbers in both diseased and normal birds.

Brown and Brenn stained sections showed Gram-positive bacilli intimately associated with early necrotic lesions on the tips of villi. Tissue sections from the intestines of sick birds permitted a proposed pathogenesis for this disease with the lesion starting at the tips of villi.

The similarity in pathogenesis and pathological lesions in this disease of broilers and Clostridium perfringens type C enteritis in baby pigs is discussed.

     

Effect of Spray-Dried Plasma Form and Duration of Feeding on Broiler Performance During Natural Necrotic Enteritis Exposure

The effect of duration of feeding (continuous or discontinued after d 14) and form (granular vs. powder) of spray-dried plasma (SDP) on performance and mortality of broilers using used litter was evaluated with 240 Ross × Ross 308 male broilers (6 broilers per pen, 8 pens per treatment). Dietary treatments were control (no SDP) or SDP as powder or granular included in the pellet and fed continuously (d 0 to 35) or discontinued after d 14. During the experiment, broilers developed necrotic enteritis, and tissue cultures were positive for Escherichia coli and Salmonella, resulting in 50% mortality on control broilers. Addition of SDP to the feed improved (P < 0.05) average daily gain, feed intake, and feed efficiency for each period of the study (d 0 to 14, 15 to 28, 29 to 35, and 0 to 35). Continuous feeding of SDP improved (P < 0.05) average daily gain, feed intake, and feed efficiency from d 15 to 35 compared with broilers fed SDP to d 14. Liveability was improved (P < 0.05) in broilers consuming SDP either for 14 d or continuously throughout the experiment compared with control broilers. Spray-dried granular plasma was more effective than spray-dried powder plasma from d 0 to 14. The results of this experiment confirmed that SDP improved broiler growth rate, feed intake, feed efficiency, and minimized enteric challenge associated with necrotic enteritis with maximal protection afforded by continuous feeding. The response to SDP was independent of age of the broiler.     

鸡传染性支气管炎病毒致病机理的研究进展

鸡传染性支气管是由鸡传染性支气管炎病毒引起鸡的一种急性高度接触性呼吸道传染病,由于病毒血清型较多,易于发生变异而难以免疫预防,成为养鸡业发展的重大阻力。文章就该病毒的致病机理方面的研究情况做一综述,为防制鸡传染性支气管炎提供科学依据。