关于肉鸡大肠杆菌病的论文

大肠杆菌是目前危害养鸡业的重要细菌性疾病之一。本病是由大肠杆菌各种血清型致病菌引起的表现多种症状的总称。

【病原】

大肠杆菌为革兰氏阴性菌，各种环境应激及鸡抵抗力下降时容易发病。

【流行特点】

各种家禽、各种龄的鸡均可感染，大肠杆菌无处不在，无处不有，饲料、水中普遍存在。

本病易通过呼吸道、污染的饲料、水中传播，当鸡群的饲养管理水平低下时，年四季均可发生，但以冬末春初多见。多雨季节和闷热季节也很多。

【重点诊断】

禽的大肠杆菌病潜伏期数小时到3天，没有特征性临床症状。病鸡一般表现为精神不振，缩脖，炸毛，闭眼等。

1.急性败血症 ：病鸡离群呆立或挤堆，拉黄白色稀粪（注意：新城疫、禽流感等病毒病前期也拉这种粪便），有呼吸困难的（支原体与其是姊妹病，所以有这种情况发生）。死鸡剖检可发现腹部皮肤紫红色，掀开皮肤，胸部肌肉紫红色，主要病变为纤维素心包炎、肝周炎、脾炎、有时脾脏变大，脾被摸下面有出血的。

这种急性型败血症很容易识别。

2.脐炎： 鸡苗会发现有很多肚脐发炎的症状，剖检可见卵黄为吸收好。（卵黄一般在10天内吸收完，我有以客户抱怨说他们当地兽医说40多天鸡卵黄没吸收掉，我都不好意思说那个兽医的资格证是怎么来的，纯属扯淡）

3.气囊炎： 这种病影响了一代又一代的肉鸡养殖户，严重时死亡率高，而且难治。

主要诊断可见气囊上不干净，大肠杆菌性气囊炎还是好治的，如果是不明原因的气囊炎，那才很难治。

4.卵黄性腹膜炎： 这种病一般是产蛋鸡，解剖时既可以看出来，不多解释。

5.大肠杆菌病还有肉芽肿、输卵管炎、出血性肠炎、眼炎、肿头综合症、腹水症、慢呼、关节炎等等。

6.一般大肠杆菌病很好认。

【实验结果与防

肉鸡大肠杆菌病Broiler'E. coli Infection Prevention of Escherichia coli infection in broiler chickens with a bacteriophage aerosol spray WE Huff, GR Huff, NC Rath, JM Balog, and AM Donoghue Poultry Production and Product Safety Research Unit, USDA, Poultry Science Center, University of Arkansas, Fayetteville 72701, USA. huff@ to an Escherichia coli isolate that is pathogenic in poultry were isolated from municipal sewer treatment facilities or poultry processing plants. Three studies were conducted to determine the efficacy of aerosol administration of bacteriophage to prevent an E. coli respiratory infection in broiler chickens. In all three studies the experimental design consisted of nine treatments with three replicate pens of 10 birds. Three treatments were not challenged with E. coli and consisted of unsprayed birds, birds sprayed with a diluent control, and birds sprayed with a combination of two bacteriophages. Six treatments were challenged with E. coli by injecting 10(4) cfu into the thoracic air sac when birds were 7, 8, or 10 d of age after being sprayed at 7 d of age with either a diluent control or a combination of two bacteriophages. In Studies 1 and 2, BW at 2 wk of age of all the birds challenged with E. coli, regardless of spray treatment, were decreased significantly from the unchallenged controls, except in Study 2 for the birds sprayed with bacteriophage and challenged at 10 d of age. There was a significant decrease in mortality in Studies 1 and 2 when the birds were challenged with E. coli immediately after bacteriophage administration and in Study 2 in birds challenged at 10 d of age. In Study 3 a suspected pre-existing E. coli infection resulted in mortality in the unchallenged, unsprayed controls, and in the diluent sprayed controls of 20 and 27%, respectively. The mortality in the unchallenged bacteriophage sprayed birds was 3%, representing a significant decrease. Mortality in Study 3 was significantly decreased in the bacteriophage-sprayed birds challenged with E. coli immediately or 1 d later but not 3 d after bacteriophage administration. The decrease in BW at 2 wk of age in challenged birds indicates that bacteriophage treatment did not provide complete protection; however, in all three studies mortality was significantly decreased, indicating that aerosol spray of bacteriophage may be practical for administration of bacteriophage and may provide an alternative to the use of antibiotics in poultry production.