The Effects of Diet Formulation and Thermal Processes Associated With Pelleting on 18-day Broiler Performance and Digestible Amino Acid Concentration

The objectives of the study were to assess performance and digestible amino acid concentration of diets fed to broilers that differed in formulation and degree of thermal processing. Basal diets were corn, soybean meal (SBM), and dried distillers grains and solubles (DDGS) based and formulations were balanced to be similar in calculated metabolizable energy and digestible amino acids. Treatments were arranged in a 3 × 3 factorial that varied in diet formulation (basal, basal + meat and bone meal (MBM), and basal + bakery byproduct (BBP)) and degree of thermal processing (unprocessed mash, pellet, double pellet). All treatments were ground to similar particle size and fed to 10 replicate raised wire cages of 10 straight-run Hubbard x Cobb 500 broiler chicks for 18 d. Broilers provided a basal + MBM diet improved FCR (P = 0.0046). Pelleting and double pelleting improved FCR compared to unprocessed mash (P = 0.0003). Formulation and processing effects interacted to affect digestible lysine, methionine, threonine, and cysteine concentrations (P < 0.05). Digestible amino acid concentration improved when basal and basal + MBM diets were thermally processed. However, digestible lysine and cysteine concentrations decreased when basal + BBP were thermally processed. In vitro available lysine results did not support digestible lysine concentration results. Thermal processing decreased trypsin inhibitor complex activity for each formulation. Nutritional benefit or detriment of thermal processes associated with pelleting was dependent on diet formulation.