The Effect of Feed Manufacture Techniques on Pathogen Reduction and Feed Nutrient Value

The Effect of Feed Manufacture Techniques on Pathogen Reduction and Feed Nutrient Value Timothy P. Boltz Experiments were conducted to evaluate how differing feed manufacture techniques, such as varying conditioning times and new equipment, can affect pathogen mitigation, feed manufacture metrics, amino acid digestibility, and enzyme recovery in feed. Feed hygienics are of increasing importance in providing safe feed to animals, and ultimately safe food for consumers. Salmonella has been identified as a major microbial hazard in animal feed that has been linked to animal and human illness. In chapter 2, the effects of standard pelleting and more thermally aggressive techniques were utilized to determine pathogen mitigation potential. Use of antibiotics has decreased in recent years due to policies and practices of poultry production, increasing opportunities for potential pathogens in feed to affect poultry and poultry products. More thermally aggressive pelleting decreased pellet mill motor load (P=0.02), increased hot pellet temperature (P=0.02), and tended to increase pellet durability (P=0.07). E. faecium ATCC 8459, as a Salmonella surrogate colonies were reduced with standard pelleting relative to inoculated mash and reduced further with more thermally aggressive pelleting (P<0.05). Standard pelleting and more thermally aggressive pelleting resulted in a 3 and 4-log reduction in E. faecium ATCC 8459 colonies respectively, relative to inoculated mash. In chapter 3, varying steam conditioning temperature and conditioning time were utilized to examine the how these interacted to affect pellet mill motor load, pellet quality, digestible amino acid concentration, and enzyme recovery. Corn and soybean meal based diets that included DDGS and meat and bone meal were conditioned at either 76°C, 82°C, or 88°C with conditioning times of either 30 or 60 seconds. Conditioning temperature and time interacted to affect pellet mill motor load (P<0.05). Motor load decreased for 30 second conditioning compared to 60 second conditioning when diets were subjected to 76 and 82°C, but motor load was similar among conditioning times at 88°C. This interaction was likely due to the result of lower feed volume in the conditioner as per 30 second conditioning obtaining greater moisture condensation and lubrication at lower conditioning temperatures. Pellet quality increased with increased conditioning temperature (P<0.05), likely associated with greater starch gelatinization and protein gelation. Lysozyme activity decreased when conditioned at 88°C (P<0.05), but was not affected by retention time. Conditioning temperature and time interacted to affect digestible amino acid concentrations of methionine, lysine, threonine, alanine, aspartic acid, glutamic acid, isoleucine, leucine, proline, and valine (P<0.05). Increased conditioning temperatures at 30 seconds increased digestible amino acid concentrations. Similarly, diets conditioned at 60 seconds increased digestible amino acid concentration between 76 and 82°C. However, the digestible amino acid concentration decreased when diets were conditioned at 60 seconds and 88°C. Perhaps negative effects on digestibility of trypsin inhibitor complexes and ingredient aleurone layers were decreased with increasing temperatures; however, the 60 second 88°C treatment may have been too thermally aggressive and rendered the proteins indigestible.