KU Center for Food Safety, College of Veterinary Medicine, Konkuk University, Seoul, Republic of Korea.
Department of Animal Science and Technology, Konkuk University, Seoul, Republic of Korea.
Poult Sci. 2021 Jan;100(1):302-313. doi: 10.1016/j.psj.2020.10.019. Epub 2020 Oct 14.
High necrotic enteritis (NE) incidence and mortality rates in poultry can be caused by Clostridium perfringens (CP) coinfected with Eimeria spp., a causative agent of coccidiosis. Banning of prophylactic use of antibiotics in feed has been accompanied by increased NE outbreaks, resulting in economically devastating losses to the broiler industry. To determine alternatives for controlling NE, we isolated CP-specific bacteriophages (BP), characterized their properties, evaluated their inhibitory effects on pathogenic CP, selected a highly effective phage (φCJ22), and used φCJ22 as a dietary supplement in experimental NE-afflicted broiler chickens. Male broilers (n = 780) were randomly assigned to 60 pens (n = 13 broilers/pen) and into 5 groups [CP-uninfected negative control (NC), basal diet (BD) without CP and BP; CP-infected positive control (PC), BD + CP; and 3 BP groups receiving low- (LP; BD + CP+10 BP), medium- (MP; BD + CP+10 BP), and high-phage (HP; BD + CP+10 BP plaque-forming units/kg) concentrations]. The results showed that MP and HP groups presented an antimicrobial activity toward clinical CP isolate strains, and the groups decreased NE lesions and mortality rates without changes in chicken performance at the end of the experimental period. After CP-challenge body weight gain and feed efficiency were significantly lower in phage-fed groups than that in the PC group (P < 0.05), and NE-associated mortality was the lowest in the HP group (P < 0.001). Moreover, histopathology revealed lesser gastrointestinal mucosal damage in the NC and BP-treated (LP, MP, and HP) groups than that in the PC group, and MP and HP significantly lowered viable CP number in the cecum content by up to 1.24log10 relative to only CP-infected PC group (P < 0.05). These findings suggest that addition of φCJ22 to chicken feed might effectively ameliorate NE, which is accompanied by reduced CP strains in the gut and compensate the performance of NE-afflicted broilers.
高坏死性肠炎（NE）发病率和死亡率可由梭状芽孢杆菌（CP）与艾美耳球虫（一种球虫病的病原体）共同感染引起。饲料中预防性使用抗生素的禁令出台后，NE 爆发增加，给肉鸡产业带来了经济上的毁灭性损失。为了确定控制 NE 的替代方法，我们分离了 CP 特异性噬菌体（BP），对其特性进行了表征，评估了它们对致病性 CP 的抑制作用，选择了一种高效噬菌体（φCJ22），并将其作为膳食补充剂用于实验性 NE 感染的肉鸡。雄性肉鸡（n=780）被随机分配到 60 个笼子（n=13 只肉鸡/笼），并分为 5 组[CP 未感染阴性对照（NC），不含 CP 和 BP 的基础日粮（BD）；CP 感染阳性对照（PC），BD+CP；和 3 个 BP 组分别接受低（LP；BD+CP+10 BP）、中（MP；BD+CP+10 BP）和高噬菌体（HP；BD+CP+10 BP 噬菌斑形成单位/千克）浓度]。结果表明，MP 和 HP 组对临床 CP 分离株表现出抗菌活性，且在实验结束时，各组降低了 NE 病变和死亡率，而鸡的性能没有变化。在 CP 攻毒后，与 PC 组相比，噬菌体喂养组的体重增加和饲料效率明显降低（P<0.05），且 HP 组的 NE 相关死亡率最低（P<0.001）。此外，组织病理学显示，与 PC 组相比，NC 和 BP 处理（LP、MP 和 HP）组的胃肠道黏膜损伤较小，而 MP 和 HP 组可使回肠内容物中 CP 活菌数分别降低多达 1.24log10，与仅 CP 感染的 PC 组相比（P<0.05）。这些发现表明，将 φCJ22 添加到鸡饲料中可能有效改善 NE，同时减少肠道中的 CP 菌株，并补偿 NE 感染肉鸡的性能。
