Berberine hydrochloride

Three isolipidic (10.10% crude lipid) and isonitrogenous (45.91% crude protein) diets were formulated, which contained 12% cassava starch (NCD), 20% cassava starch (HCD) and 20% cassava starch adding 50 mg/kg berberine (HCD + BBR), respectively. All the ingredients of each diet were crushed and sieved through a 100-mesh sieve. The BBR (Berberine hydrochloride, Solarbio, Beijing, China) was thoroughly mixed by progressive enlargement method after accurate weighing. Then, all the ingredients were completely mixed and extruded into 2 mm diameter pellets under the following extrusion conditions: feeding section (90°C/5 s), compression section (150°C/5 s), and metering section (120°C/4 s) using a twin-screwed extruder (Jinan Dingrun Machinery CO., LTD., Jinan, China). The pellets were dried in an oven (60°C) and stored at 4°C for 7 weeks. The formulation and approximate composition of the experimental diets were shown in Table 1.

Antimicrobial agents include berberine hydrochloride (BBH), amikacin, ciprofloxacin (Solarbio, Beijing, China), sulbactam (Aladdin, Shanghai, China), tigecycline (BioVision, San Francisco, USA), meropenem, and tetracycline (National Institutes for Food and Drug Control, Beijing, China). They were dissolved in sterile distilled water and stored at -20°C before the test. Unless otherwise noted, all antimicrobial powders have a purity greater than 98%. Efflux pump inhibitors carbonyl cyanide m-chlorophenylhydrazone (CCCP) and reserpine were purchased from Solarbio (Beijing, China), and phenylalanine-arginine β-naphthylamide (PAβN) from MedChemExpress (Shanghai, China).