Assessment of sterilization methods on by-products used in Total Mixed Ration for safe feed production

Abstract.: Several studies focus on finding alternative feed for livestock farms to reduce cost in breeding. Formulating Total Mixed Ration (TMR) feed with agricultural by-products (mushroom, palm kernel expeller, soy sauce cake etc.) via fermentation using effective microbes as facilitators has been in consideration lately. Unwanted microbes usually contaminate and compete with the effective microbes intended to act on the by-products. Establishing an efficient fermentation protocol for a safe by-product feed is the research focus. Mixed by-products were collected from TMR plant in Gyeongju, South Korea using aseptic techniques. Initial analyses indicated the presence of Bacillus cereus (3.0 x 10⁶ CFU/g), Yeast (less than 10⁶ CFU/g) and Lactic Acid Bacteria (10⁶ CFU/g) in the untreated samples. Different selected conditions of steam treatment (121°C, 100°C, and 80°C at 15 minutes respectively) and Ultra Violet (UV) radiation (320 nm for 15 minutes) were investigated. Enumeration for the pathogenic microbe (Bacillus cereus) after sterilization confirmed presence of less than 10⁶ CFU/g at the different steam treatment conditions whereas UV treatment reduced the concentration to 10⁶ CFU/g. Steam sterilization was more efficient and considered for inclusion in setting up a fermentation smart tank.