Effect of the Steam Conditioning and Pelleting Process on the Microbiology and Quality of Commercial-Type Poultry Feeds

Effects of variations in steam conditioning and pelleting poultry feed to eliminate Salmonella were investigated in a commercial pellet mill. Layer-breeder and broiler-starter rations differing primarily in fat and limestone content were evaluated. Total bacteria counts were reduced only slightly, but Enterobacteriaceae counts were reduced appreciably by steam conditioning; however, pelleting was also necessary to eliminate Enterobacteriaceae consistently. Salmonella were present in about 50% of the feed samples before conditioning and in only about 4% of all samples after conditioning and pelleting. No Salmonella was detected after pelleting with high or very high steam pressure conditioning. Moisture content of the feed remained in an acceptable range regardless of steam pressure used. Temperature of the feed following the conditioning process was 134 to 135 F (57 C), 162 to 169 F (72 to 76 C), and 181 to 187 F (83 to 86 C) with low, medium, and high steam, respectively. The layer-breeder pellets were slightly more durable than the broiler-starter pellets, and overall pellet durability increased with increasing steam pressure.