Fig. 3

Effects of EAI on phenolic and indole compounds concentrations in the feces of pigs with different CP levels diets. (Con-LP, ; Ant-LP, ; Con-NP, ; Ant-NP, ). a On d 77. b On d 185. EAI: early antibiotic intervention. The commercial creep feed with or without in-feed antibiotics (50 mg/kg olaquindox, 50 mg/kg oxytetracycline calcium, and 50 mg/kg kitasamycin) was fed to pig from d 7 to d 42. Thereafter, the control and antibiotic group were further randomly assigned to provide a normal (20%, 18%, 14% CP from d 42 to d 77, d 77 to d 120, d 120 to d 185, respectively) or low CP diet (16, 14, 10% CP from d 42 to d 77, d 77 to d 120, d 120 to d 185, respectively), respectively. The P values indicate main effects for antibiotic (A), protein level (C) and their interaction (AC), respectively