Effect of enzyme supplementation of broiler diets based on corn and soybeans

Digestibility of diets based on corn and soybean meal or soybeans treated b y roasting or extrusion, with or without an enzyme supplementation, was mea sured by "true" (Sibbald) methods, by analysis of excreta, and by analysis of ileal digesta. Only analysis of ileal digesta was able to consistently m easure differences between soybean and enzyme treatments in the digestibili ty of CP, starch, fat, and ME. The amino acid (AA) digestibility of the die ts was measured by analysis of the ileal contents. Whereas enzyme supplemen tation improved overall CP digestibility by 2.9%, this improvement was not equal for all AA. Of the AA most important for broilers fed corn-soybean di ets, the digestibilities of Lys, Met, and Arg were not improved or not impr oved significantly by the enzyme supplementation; however, that of Val was improved by 2.3% and that of Thr was improved by 3.0%. A performance trial demonstrated that enzyme supplementation with equal diet formulation improv ed BW and the feed conversion ratio by 1.9 and 2.2%, respectively. A second performance trial compared standard diet formulations with formulations us ing enzyme supplementation and energy levels that were reduced by the amoun t of improvement provided by the inclusion of enzyme in the first performan ce trial. No difference was seen between treatments, showing that the impro vement of nutrient utilization brought about by enzyme supplementation comp letely compensated for the reduced energy content. Whereas enzyme supplemen tation should allow a reduction in CP formulation as well, individual AA we re not improved equally by supplementation and should also be balanced.