Hygienic pelleting can decrease Hubbard × Ross 708 apparent ileal amino acid digestibility, broiler performance, and increase digestible amino acid requirement

SUMMARY: To reduce pathogenic bacteria such as Salmonella in feed and ensure a high-quality pellet, diets for broilers, turkeys, and breeders may be pelleted using high conditioning temperatures and extended times. However, increased conditioning temperature and time may alter amino acid conformation regarding secondary and tertiary structure, decrease digestibility and subsequent bird performance, and necessitate increased amino acid formulation density. The objective of this study was to evaluate increased conditioning temperature and exposure time within the pelleting process using a hygienizer (hygienic pelleting) in diets that vary in digestible lysine and corresponding amino acid ratio on Hubbard × Ross 708 starter broiler performance, apparent ileal amino acid digestibility (AIAAD), and requirement. A 5 × 2 factorial arrangement of treatments with 5 levels of digestible lysine (−20, −10%, 2019 Ross Broiler Starter Nutrition recommendation, +10, and +20%) and 2 techniques of pelleting (standard and hygienic) was utilized in a randomized complete block design. Standard pelleting utilized 77°C conditioning for 30 s and hygienic pelleting utilized 88°C conditioning for 60 s and 6-min retention time in a hygienizer. Each treatment was fed to 12 replicate pens of 10 male broiler Hubbard × Ross 708 chicks for a 21-day period. Standard pelleting and hygienic pelleting demonstrated a 1.19 and 1.37% digestible Lys requirement, respectively, using the 2 straight line, 1-breakpoint broken-line regression model. Performance data, AIAAD, and the broken-line regression model suggest an approximate 10% increase in digestible Lys and corresponding amino acid ratio relative to 2019 Ross Broiler Starter Nutrition Specifications for Hygienic Pelleting. Nutritionists should be cognizant that nutritional detriment may accompany procedures used to create hygienic pelleted feed.