title: The feed mixture was formulated as 1:2 (TD) oxytetracycline bacterial residue:soya meal (mass ratio, dry weight), third day
design: To target the hypervariable V4V5 region of the bacterial 16S rRNA gene, the universal primers 314F and 828R were selected for the amplification of gut DNA samples. The specific methods and procedures, which contained the PCR reaction system and conditions, and the PCR product purification and quantification.