BACKGROUND Necrotic enteritis is a significant problem to the poultry industry globally and, in Norway up to 30% of Norwegian turkey grow-outs can be affected. However, despite an awareness that differences exist between necrotic enteritis in chickens and turkeys, little information exists concerning the pathogenesis, immunity, microbiota or experimental reproduction of necrotic enteritis in turkeys. In particular, it is important to determine the appearance of the gross lesions, the age dependency of the disease and the role of netB toxin of Clostridium perfringens. To this end, we report our findings in developing an in vivo experimental model of necrotic enteritis in turkeys. RESULTS A four tier (0-3) scoring system with clearly defined degrees of severity of macroscopic intestinal lesions was developed, based on 2312 photographic images of opened intestines from 810 B.U.T. 10 or B.U.T. Premium turkeys examined in nine experiments. Loss of macroscopically recognizable villi in the anterior small intestine was established as the defining lesion qualifying for a score 3 (severe intestinal lesions). The developed scoring system was used to identify important factors in promoting high frequencies of turkeys with severe lesions: a combined Eimeria meleagrimitis and Clostridium perfringens challenge, challenge at five rather than 3 weeks of age, the use of an Eimeria meleagrimitis dose level of at least 5000 oocysts per bird and finally, examination of the intestines of 5-week-old turkeys at 125 to 145 h after Eimeria meleagrimitis inoculation. Numbers of oocysts excreted were not influenced by Clostridium perfringens inoculation or turkey age. Among three different lesion score outcomes tested, frequency of severe lesions proved superior in discriminating between impact of four combinations of Clostridium perfringens inoculation and turkey age at challenge. CONCLUSIONS This study provides details for the successful establishment of an in vivo model of necrotic enteritis in turkeys.

中文翻译：

---

在火鸡中建立实验性坏死性肠炎模型-产气荚膜梭状芽胞杆菌，艾美球菌性小肠炎和宿主年龄对严重肠病变发生率的影响。

背景技术坏死性肠炎是全球家禽业的重要问题，在挪威，多达30％的挪威火鸡生长会受到影响。然而，尽管意识到在鸡和火鸡之间存在坏死性肠炎之间的差异，但是关于火鸡坏死性肠炎的发病机理，免疫力，微生物群或实验繁殖的信息很少。尤其重要的是，确定总体损伤的外观，疾病的年龄依赖性以及产气荚膜梭菌的netB毒素的作用。为此，我们报告了在开发火鸡坏死性肠炎的体内实验模型中的发现。结果开发了一种四层（0-3）评分系统，明确了宏观肠道损害的严重程度，基于在9个实验中检查的来自810 BUT 10或BUT Premium火鸡的开肠的2312张照片图像。宏观上可识别的绒毛在小肠前部的损失被确定为限定评分为3级的严重病变（严重肠病变）。发达的评分系统用于确定导致火鸡高频率带严重病灶的重要因素：合并的艾美球菌性小肠炎和产气荚膜梭状芽孢杆菌挑战，在五周龄而不是3周龄时进行挑战，使用至少艾美球菌性小肠炎剂量水平每只鸡5000个卵囊，最后，在接种艾美叶霉菌性手足炎后125至145小时检查5周龄火鸡的肠道。产气荚膜梭状芽孢杆菌的接种量或火鸡年龄都不会影响排泄的卵囊的数量。在测试的三种不同病变评分结果中，严重病变的频率被证明在区分四种产气荚膜梭状芽孢杆菌接种组合的影响和挑战时的火鸡年龄方面具有优势。结论本研究为成功建立火鸡坏死性肠炎的体内模型提供了细节。