Effects of varying conditioning temperature and mixer-added fat on feed manufacturing efficiency, 28- to 42-day broiler performance, early skeletal effect, and true amino acid digestibility

Abstract

Three experiments (EXP) were conducted with the objective of evaluating the effects of varying steam conditioning temperatures (CT) and mixer-added fat (MAF) on a practical broiler finisher diet on feed manufacture variables (EXP 1), 28- to 42-d broiler performance (EXP 2), and early skeletal effect using 3-to 21-d broiler performance and tibiae ash measurements and true amino acid digestibility using cecectomized roosters (EXP 3). For all EXP, we used a 3 CT (74, 85, or 96°C) by 2 MAF (low or high) factorial arrangement, resulting in 6 experimental diets. Prior to EXP 2 and 3, all diets were ground to a common crumble size. In EXP 1, increasing both CT and MAF decreased relative electrical energy use at the pellet mill. In EXP 2, feeding finisher diets manufactured utilizing increased CT and decreased MAF to broilers from 28 to 42 d resulted in increased FCR. Also, CT by MAF interactions demonstrated the highest BW gain when birds were fed diets with high MAF, conditioned at 85°C. In EXP 3, feeding diets manufactured in EXP 1 to broilers from 3 to 21 d resulted in no significant effects on live performance variables. However, a significant CT by MAF interaction was observed, where chicks fed diets using low MAF conditioned at 85 and 96°C resulted in incrementally increased percent tibia ash over those with high MAF. In addition, based on true amino acid digestibility data, altering MAF and especially CT can affect the digestibility of several amino acids.