Four experiments at the Division of Agriculture-University of Arkansas Applied Broiler Research Unit were conducted (2 in Cobb 500 male broilers and 2 in Ross 708 male broilers). Results indicated that increasing dietary leucine to lysine ratios from 1.35 to 1.55 does not result in practical antagonisms. Further, corn and soybean meal-based diets resulted in classic broiler responsiveness to increasing amino acid density (i.e., soybean meal), but when corn based distillers grains were added, the amino acid density response was altered and worsened in terms of performance and efficiencies.

Amino acid density research in corn and soybean-based diets, but not corn, soybean meal, and corn distillers-based diets, followed conventional wisdom as to increasing amino acid density via soybean meal to improve broiler efficiency. This work points to increased broiler responsiveness when fed corn and soybean meal diets, without high protein distillers grains inclusion, are fed Further, the consistency of soybean meal was measured by broiler treatment responses.