Abstract: [Objective] To establish a method for preparing turbid microbial suspension agent and to evaluate its stability. [Method] Microbial water suspension system was prepared with xanthan gum and sodium carboxymethyl cellulose as stabilizers and microbial feed additive powder agent as suspension components. The stability of the prepared suspension agent was evaluated using indexes including stability coefficient, viscosity, storage stability, cold storage stability, and total number of viable bacteria. [Result] With the increase of stabilizer proportion, the stability coefficient of suspension agent increased gradually. When 0.20% stabilizer was added, the stability coefficient of the system rose to 91.38% which was significantly （P<0.01） higher than the control. The viscosity of the suspension system elevated with the increase of stabilizer addition amount and the decrease of storage temperature. When the stabilizer addition ratio was 0.20%, the system had no stratification and reached a stable state. After 24 hours of cold storage at 4 ℃, the number of viable bacteria in the suspension agent with 0.10% stabilizer declined. With 0.10%-0.25% stabilizer addition, the number of viable bacteria was significantly （P<0.05） lower than the control, but remained above 10⁹ CFU/mL. [Conclusion] There is no stratification in the prepared turbid microbial suspension agent for feed use when the addition amount of stabilizer is 0.20%. The number of viable bacteria in the prepared suspension agent remains above 10⁹ CFU/mL after 24 hours of cold or room temperature storage, ensuring the effective amount of viable bacteria in the microbial agent for feed use.

Key words: microbial agent for feed use, suspension agent, stability coefficient, viscosity