Hatch weight (HW) affects broiler growth and low HW (LHW) often leads to suboptimal performance. Sodium butyrate (SB) has been shown to promote growth through enhanced intestinal health. This study investigated how broilers with different HW responded to in ovo SB injection and whether SB could enhance gut health and performance in LHW chicks. Ross 308 broiler eggs were injected on incubation d 12 with physiological saline (control) or SB at 0.1% (SB1), 0.3% (SB3), or 0.5% (SB5). Post-hatch, male chicks from each treatment were categorized as high HW (HHW) or LHW and assigned to 8 groups in a 4 × 2 factorial design. Production parameters were recorded periodically. Intestinal weight, length, and gene expression related to gut barrier function and immune response were examined on d 14 and 42. Cecal microbiota dynamics and predicted functionality were analyzed using 16S rRNA gene sequencing. SB treatments did not affect hatchability. HHW-control group exhibited consistently better weight gain and FCR than LHW-control group. SB dose-dependently influenced performance and gut health in both HW categories, with greater effects in LHW broilers at 0.3%. LHW-SB3 group attained highest body weight on d 42, exceeding controls but not significantly differing from HHW-SB3 group. LHW-SB3 group showed upregulation of gut-barrier genes CLDN1 in ileum, TJP1 in jejunum and anti-inflammatory cytokine IL-10 in both jejunum and ileum on d 14. Additionally, LHW-SB3 group upregulated mucin-producing MUC6 gene in ileum, while HHW-SB5 group increased pro-inflammatory IL-12p40 cytokine in caecum on d 42. LHW-SB3 group demonstrated shorter relative intestinal lengths, while HHW-SB5 had longer lengths. HHW-control group had higher bacterial diversity and growth-promoting bacteria while LHW-control group harbored the potential pathogen Helicobacter. SB reshaped gut microbiota biodiversity, composition, and predicted metabolic pathways in both HW categories. The LHW-SB3 group exhibited highest alpha diversity on d 14 and most beneficial bacteria at all timepoints. HHW-SB5 group presented increased pathogenic Escherichia-Shigella and Campylobacter on d 42. HW significantly affects subsequent performance and SB has differential effects based on HW. LHW chicks benefited more from 0.3% SB, showing improvements in growth, intestinal development, health, and gut microbiota characteristics.

中文翻译：

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在卵中，丁酸钠给药对低孵化体重和高孵化体重肉鸡的生长性能、肠道屏障功能、免疫反应和肠道微生物群特性的影响不同


孵化重量 （HW） 会影响肉鸡的生长，而低 HW （LHW） 通常会导致性能不佳。丁酸钠 （SB） 已被证明可以通过增强肠道健康来促进生长。本研究调查了不同 HW 的肉鸡对卵 SB 注射的反应，以及 SB 是否可以增强 LHW 雏鸡的肠道健康和生产性能。在孵化 d 12 中，用 0.1% （SB1）、0.3% （SB3） 或 0.5% （SB5） 的生理盐水（对照）或 SB 注射 Ross 308 枚肉鸡蛋。出雏后，来自每个处理的雄性雏鸡被归类为高 HW （HHW） 或 LHW，并以 4 × 2 因子设计分为 8 组。定期记录生产参数。在第 14 天和第 42 天检查与肠道屏障功能和免疫反应相关的肠道重量、长度和基因表达。使用 16S rRNA 基因测序分析盲肠微生物群动力学和预测功能。SB 处理不影响孵化率。HHW 对照组的体重增加和 FCR 始终优于 LHW 对照组。SB 剂量依赖性地影响了两个 HW 类别的生产性能和肠道健康，在 LHW 肉鸡中的影响更大，为 0.3%。LHW-SB3 组在第 42 天体重最高，超过对照组，但与 HHW-SB3 组无显著差异。LHW-SB3 组在 d 14 时显示回肠肠道屏障基因 CLDN1 、空肠 TJP1 和空肠和回肠抗炎细胞因子 IL-10 上调。此外，LHW-SB3 组上调回肠产粘蛋白的 MUC6 基因，而 HHW-SB5 组在第 42 天增加盲肠中促炎性 IL-12p40 细胞因子。LHW-SB3 组表现出较短的相对肠长，而 HHW-SB5 具有较长的肠长。 HHW 对照组具有较高的细菌多样性和促生长细菌，而 LHW 对照组携带潜在的病原体 Helicobacter。SB 重塑了两个 HW 类别中肠道微生物群的生物多样性、组成和预测的代谢途径。LHW-SB3 组在第 14 天表现出最高的 α 多样性，并且在所有时间点都表现出最有益的细菌。HHW-SB5 组在 d 42 时致病性 Escherichia-Shigella 和 Campylobacter 增加。HW 显著影响后续性能，SB 与 HW 的影响不同。LHW 雏鸡更多地受益于 0.3% SB，在生长、肠道发育、健康和肠道微生物群特性方面表现出改善。