甲砜霉素中毒对肉仔鸡免疫器官损伤的病理学影响

Pathologic effect of thiamphenicol poisoning experimently on immune organs of chickens

4日龄AA+肉鸡304只,随机分为4组,分别以0(对照组)、500(Ⅰ组)、1 000(Ⅱ组)1、500(Ⅲ组)mg/kg饲料的甲砜霉素剂量饲喂6周,研究甲砜霉素对肉鸡免疫器官的病理学损害。试验开始后每天观察肉鸡的临床症状,每周称重1次计算平均体质量,分别在第2、4、6周测定红细胞数量、血红蛋白含量、免疫器官脏器系数,并取免疫器官作石蜡切片以研究甲砜霉素对肉鸡免疫器官的病理组织学影响。结果显示,对照组、Ⅰ组、Ⅱ组和Ⅲ组的死亡率分别为0%、9.21%、64.47%和68.42%;中毒鸡表现为食欲减退、体质量增长缓慢、贫血;法氏囊、脾脏和胸腺脏器系数显著降低,淋巴细胞减少。结果表明,即使以500 mg/kg饲料的甲砜霉素持续饲喂肉鸡,均可对肉鸡的免疫器官结构造成明显损伤,尤其是体液免疫器官,并且这种损伤存在剂量效应关系。

The harmful effect of dietary thiamphenicol on the pathology of immune organ in the chicken was investigated. 304 four-day-old AA＋ chickens were randomly divided into four groups, and fed on diets as follows：0,500, 1 000 and 1 500 mg/kg for 6 weeks. Clinical signs and mortality were observed daily and body weight was measured weekly during the treatment. After 2,4 and 6 weeks, five of＇three treated groups and control group were examined for the amounts of RBC, hemoglobin level, immune organs ralative weight and histology of the immune organs by paraffin section. The mortality were 0%, 9.21 %, 64.47% and 68.42%, respectively. Appetite of chickens receiving TAP decreased,and growth rate was much retarded significantly. The Hb level and the RBC amounts dropped. Organs ralative weight of bursa of Fabricius and spleen and thymus decreased; leukomonocyte of the immune organs in the chicken decreased. The results demonstrated that 500 mg/kg thiamphenicol in diet could induce morphological injury of immune organ especially humoral immune organ,and damage degrees may be relative to thiamphenicol dosage in a certain extent.