Lowering the dietary protein levels by the use of synthetic amino acids and the use of a mono component protease

Abstract

Responses of broilers to dietary amino acids (AA) have been extensively studied especially after their synthetic and crystalline forms became available. Synthetic (DL-Met and Met analogue) as well as crystalline (l-Lys and l-Thr) AA are now widely used in commercial production diets to reduce crude protein (CP) levels to allow competitive bird performance. In parallel, birds diets formulated without excess CP have reduced nitrogen excretion as well as lower costs. Diet composition affects the order of limiting AA after Thr and this has led to some debate on the feasibility of including the next limiting AA, which would be the fourth, in most of the scenarios. Using maize-soy type diets, the literature suggests that Val is the fourth AA limiting. As the commercial cost of l-Val is progressively reduced, concerns have been raised on the effectiveness of its supplementation to produce broiler responses that are similar compared with feed that does not contain this AA. Antagonisms between branched-chain amino acids (BCAA) have been reported in the past; however, their use in the current maize-soy diet commercial setting is unlikely. Formulation of diets with crystalline l-Val can potentially modify the ratio between BCAA as it is supplemented in diets that are further reduced in CP. Increased availability of AA can also be achieved when diets are supplemented with exogenous proteases; however, the resulting impact in the total profile of AA is different because a wider group of AA becomes simultaneously available when compared to diets receiving addition of synthetic/crystalline AA one by one. A scenario of CP reduction in diets seems clear with the increasing use of supplemental AA along with protease in broiler diets. The knowledge of CP reduction strategies, such as protease and synthetic AA supplementation, can be a valuable asset due to the competitive nature of broiler meat production business.