Controlling enteric diseases of broilers is crucial. Among many additives, organic acids (OA) and their blends are gaining attention to combat diseases in the post-antibiotic era. The current study evaluated the potentials of short-chain fatty acids (SCFA) and medium-chain fatty acids (MCFA) blends and/or phenolic compounds on intestinal integrity, intestinal pH, caecal microbiota, and caecal SCFA profiles of broilers under necrotic enteritis (NE) challenge. The additives used were: (A) a blend of SCFA, MCFA, and a phenolic compound (SMP), (B) a blend of free and buffered SCFA with MCFA (SMF), and (C) a blend of free and buffered SCFA with a high concentration of MCFA (SHM). A total of 1,404 male parental chicks of Ross 308 broilers were randomly allocated to 78 floor pens on hatching day with 6 treatments replicated 13 times with 18 birds per pen. The treatments were: UCC, unchallenged control; CHC, challenged control; BAC, challenged group plus zinc bacitracin; SMP, challenged group plus additive SMP; SMF, challenged group plus additive SMF; SHM, challenged group plus additive SHM. Birds were challenged with field-strain Eimeria spp. on d 9 and Clostridium perfringens on d 14. Birds challenged with NE increased fluorescein isothiocyanate dextran (FITC-d) concentration in serum, reduced acetate and butyrate concentrations, and increased Bacteroides and C. perfringens load in the caeca (P < 0.05). Birds fed additives decreased FITC-d from gut to serum, reduced Bacteroides (d 16, P < 0.05) and numerically reduced C. perfringens load compared to CHC group. Birds fed additive SHM had higher concentrations of acetate and butyrate (d 21, P < 0.05) than CHC group but were not different from SMP and SMF groups. All the additives exhibited similar intestinal protection against NE compared to the BAC group indicated by FITC-d concentration in serum, acetate, propionate and butyrate concentrations in the caeca, and caecal bacterial loads except for the C. perfringens (P > 0.05). The SMP group had a higher load compared to BAC (P < 0.05). These findings suggest the promising effects of OA blends as alternatives to BAC to ameliorate the impact of NE challenge of broilers as indicated by improved intestinal health.

控制肉鸡的肠道疾病至关重要。在许多添加剂中，有机酸 (OA) 及其混合物在后抗生素时代对抗疾病的作用越来越受到关注。目前的研究评估了短链脂肪酸 (SCFA) 和中链脂肪酸 (MCFA) 混合物和/或酚类化合物对坏死性肠炎下肉鸡肠道完整性、肠道 pH 值、盲肠微生物群和盲肠 SCFA 谱的潜力。 NE）挑战。使用的添加剂是：(A) SCFA、MCFA 和酚类化合物 (SMP) 的混合物，(B) 游离和缓冲 SCFA 与 MCFA (SMF) 的混合物，以及 (C) 游离和缓冲 SCFA 的混合物含有高浓度的 MCFA (SHM)。Ross 308肉鸡的1,404只亲代雄性雏鸡在孵化日随机分配到78个地板栏，6个处理重复13次，每栏18只鸡。处理是：UCC，未受攻击的对照；CHC，挑战控制；BAC，攻击组加杆菌肽锌；SMP，挑战组加附加 SMP；SMF，挑战组加附加 SMF；SHM，挑战组加上添加剂 SHM。鸟类受到野外应变的挑战艾美耳属。第 9 天，产气荚膜梭菌在第 14 天。 用 NE 攻击的鸟类增加了血清中异硫氰酸荧光素葡聚糖 (FITC-d) 的浓度，降低了乙酸盐和丁酸盐的浓度，并增加了盲肠中拟杆菌和产气荚膜梭菌的负荷（P  < 0.05）。与 CHC 组相比，喂食添加剂的鸡从肠道到血清的 FITC-d 减少，拟杆菌减少（第 16 天，P  < 0.05），并且在数值上减少了产气荚膜梭菌负荷。饲喂添加剂 SHM 的家禽具有更高浓度的醋酸盐和丁酸盐（第 21 天，P < 0.05) 与 CHC 组相比，但与 SMP 和 SMF 组没有区别。与 BAC 组相比，所有添加剂对 NE 表现出相似的肠道保护，由血清中的 FITC-d 浓度、盲肠中的乙酸盐、丙酸盐和丁酸盐浓度以及除C外的盲肠细菌负荷所指示。产气荚膜( P  > 0.05)。与 BAC 相比，SMP 组具有更高的负荷（P  < 0.05）。这些发现表明，OA 混合物作为 BAC 的替代品，在改善肠道健康所表明的改善肉鸡 NE 挑战的影响方面具有良好的效果。