Effect of dietary fiber on the relative messenger RNA (mRNA) expression of intestinal development-related genes in growing pigs. Control, corn–soybean meal-based diet (1.5% CF). Beet pulp, corn–soybean meal + beet pulp-based diet (5.74% CF). Pairing, corn–soybean meal-based diet (the feed intake was equal to the beet pulp group, 1.5% CF). EGF, epidermal growth factor; IGF-1, insulin-like growth factor 1; GLP-2, glucagon-like peptide 2; IGF-1R, insulin-like growth factor 1 receptor; GLP-2R, glucagon-like peptide 2 receptor. a,b Within a row, means without a common superscript letter differ (p < 0.05).