背景:坏死性肠炎(NE)是一种由产气荚膜梭菌引起的感染性肠道疾病(C.产气荚膜)现在正在重新出现,并引起家禽业的关注。以前,在饲料中补充抗生素是最流行的产气荚膜梭菌控制策略。然而,随着禁止在牲畜饲料中补充促进生长的抗生素,抗生素的替代品对于控制坏死性肠炎至关重要。抗生素的可能替代可以是中链或长链脂肪酸(MCFA或LCFA),因为它们能够破坏细胞膜,这进而导致细菌死亡。在这项研究中,不同组合与微囊化辛酸(C8:0)的体外抗菌活性,癸酸(C10:0),分析了月桂酸(C12:0)和肉豆蔻酸(C14:0)对产气荚膜梭菌的作用以及在肉鸡中对NE诱导的产气荚膜梭菌的体内控制。
结果:最低抑菌浓度(MIC)和最低杀菌浓度(MBC)测定结果表明,三种不同的中/长链脂肪酸组合对A型产气荚膜梭菌的抗菌活性不同(CVCC52,质量控制),产气荚膜杆菌A型菌株(C8-1),产气荚膜梭菌G型菌株(D25)和产气荚膜梭菌G型菌株(MZ1)。具体来说,C12:0和C14:0(C12-14)的组合对四种产气荚膜梭菌(MIC≤12.5μg/mL,MBC=50μg/mL),其次是C10:0和C12:0(C10-12)的组合(MIC,MBC≤50μg/mL)。体内研究,在818只杂交鸡中,有189只饲喂以小麦为基础的饮食,并随机分为九组,六个治疗组分别补充了高剂量(1g/kg)或低剂量(0.5g/kg)的三种组合。其余三组采用阿维霉素阳性组补充剂(0.01g/kg),受感染的对照和未感染的对照。从第14天到第17天用产气荚膜梭菌攻击所有鸡,除了未感染的对照组中的那些。在第20天,计算十二指肠和空肠坏死病变评分,结果表明,C12-C14高剂量组(1.43±0.23,0.48±0.13)和C10-12高剂量组(1.52±0.19,0.48±0.11)与感染组(2.86±0.21,1.20±0.28)相比,有明显下降。
结论:这一发现表明,日粮微囊化C12-C14和C10-C12可以抑制鸡产气荚膜梭菌的生长,这证明了作为替代用于由产气荚膜梭菌引起的坏死性肠炎的抗生素的可行性。
BACKGROUND: Necrotic enteritis (NE) is an infectious intestinal disease caused by Clostridium perfringens (C. perfringens) that is now re-emerging and causing concern within the poultry industry. Previously, the supplementation of antibiotics in feed was the most popular control strategy against C. perfringens. However, with the ban on supplementing growth-promoting antibiotics in livestock feed, alternatives to antibiotics will be essential in order to control necrotic enteritis. A possible alternative to antibiotics could be the medium or long chain fatty acids (MCFA or LCFA) as these are able to destroy cell membranes which in turn results in the death of bacteria. In this
study, the in vitro antimicrobial activity of different combinations with microencapsulated caprylic acid (C8: 0), capric acid (C10: 0), lauric acid (C12: 0) and myristic acid (C14: 0) against C. perfringens and in vivo control the NE-inducing C. perfringens in broiler chicken were analyzed.
RESULTS: The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assay results revealed that three different combinations of medium/long chain fatty acids varied in antimicrobial activities against C. perfringens type A strain (CVCC52, quality control), C. perfringens type A strain (C8-1), C. perfringens type G strain (D25) and C. perfringens type G strain (MZ1). Specifically, combination of C12: 0 and C14: 0 (C12-14) showed the highest antimicrobial activity against the four strains of C. perfringens (MIC ≤ 12.5 μg/mL, MBC = 50 μg/mL), followed by the combination of C10: 0 and C12: 0 (C10-12) (MIC, MBC ≤ 50 μg/mL). The in vivo
study, 189 of 818-crossbred chickens that were fed a wheat-based diet and randomly divided into nine groups, with six treatment groups supplemented with either a high dose (1 g/kg) or low dose (0.5 g/kg) of three combinations respectively. The remaining three groups comsisted of a positive group supplement with avilamycin (0.01 g/kg), an infected control and an uninfected control. All chickens were challenged with C. perfringens from day 14 to day 17, except those in the uninfected control group. On day 20, the duodenum and jejunum necrotic lesions scores were calculated and the results showed that there was significant decrease in the C12-C14 high dose group (1.43 ± 0.23, 0.48 ± 0.13) and the C10-12 high dose group (1.52 ± 0.19, 0.48 ± 0.11) compared to the infected group (2.86 ± 0.21, 1.20 ± 0.28).
CONCLUSIONS: This finding indicated that dietary microencapsulated C12-C14 and C10-C12 could inhibit the growth of C. perfringens in chickens, which proves is viability to serve as an alternative to antibiotics used for necrotic enteritis caused by C. perfringens.