Table S1 Correlation analysis between key cecal bacterial genera and growth performance, intestinal morphology, and barrier function indicators in 14-day-old broilers

This table presents the correlation analysis results between 9 key cecal bacterial genera and 17 indicators related to growth performance, intestinal morphology and intestinal barrier function in 14-day-old broilers, with * (P＜0.05) and ** (P＜0.01) marking the significance levels of correlations. Among them, the genus Alistipes exhibited a strong positive effect, showing extremely significant positive correlations with average daily feed intake, average daily gain and body weight, and an extremely significant negative correlation with feed-to-gain ratio; it also had significant/extremely significant positive correlations with intestinal morphological indicators such as jejunal villus height and villus-to-crypt ratio, as well as barrier indicators including jejunal ZO-1 and OCCLUDIN, and extremely significant negative correlations with jejunal and ileal crypt depth. The genus Bacteroides exerted a positive influence on intestinal morphology, with significant positive correlations with jejunal and ileal villus height, an extremely significant negative correlation with ileal crypt depth and an extremely significant positive correlation with ileal villus-to-crypt ratio, yet no significant correlations with growth performance indicators. The genus Oscillibacter had a weak positive correlation, only showing significant positive correlations with average daily gain and body weight and a certain positive correlation with some jejunal barrier indicators. In contrast, Faecalibacterium, Escherichia-Shigella, Fournierella, Flavonifractor, Negativibacillus and Pseudoflavonifractor all presented negative correlations to varying degrees. Specifically, Escherichia-Shigella and Pseudoflavonifractor had extremely significant negative correlations with average daily gain and body weight and extremely significant positive correlations with feed-to-gain ratio; Flavonifractor and Negativibacillus had a particularly significant negative impact on ileal morphology. These genera generally showed negative correlations with intestinal villus height, positive correlations with crypt depth, significant/extremely significant negative correlations with villus-to-crypt ratio, and also negative correlations with some intestinal barrier indicators. Overall, the cecal bacterial genera had more significant correlations with jejunal barrier function indicators (ZO-1, MUC2, OCCLUDIN) in broilers, while their effects on ileal barrier indicators were mostly weak and without significant markings.