Metabolizable energy and digestible nutrient values of protease-supplemented field pea for broiler chicken

A study was conducted to determine the effects of protease supplementation of field pea (in comparison with soybean meal; SBM) for broilers on apparent metabolizable energy (AMEn) and standardized ileal digestibility (SID) of amino acids (AA). One hundred and forty broiler chicks were divided into 35 groups of 4 birds/group and fed 5 diets in a completely randomized design (7 groups/diet) from 14 to 21 d of age. The diets were cornstarch-based containing SBM or field pea as the sole protein source without or with protease (ProSparity 250^TM; CBS Bio Platforms, Calgary, AB, Canada) in 2 × 2 factorial arrangement, and N-free diet. Protease was added to diets to supply 6,250 U/kg. Digestibility of AA and N retention for feedstuffs were determined by the direct method, whereas digestibility and retention of energy for feedstuffs were determined by the difference from the N-free diet. On as fed basis, SBM and field pea contained 90.0 and 88.9 dry matter, 46.6 and 20.2 % crude protein, 2.88 and 1.47 % Lys, and 14.3 and 14.7 % non-starch polysaccharides, respectively. On as fed basis, the AMEn value for field pea was lower (P < 0.05) than that of SBM (2,006 vs. 2,414 kcal/kg). Also, the SID values of most indispensable AA in field pea were lower (P < 0.05) than those in SBM. Feedstuff (field pea vs. SBM) and protease did not interact on AMEn and SID of AA values. The supplemental protease increased (P < 0.05) AMEn values of the SBM and field by an average of 187 kcal/kg but decreased (P < 0.05) the SID values of all indispensable AA (except His) for the SBM and field, by an average of 2.7 percentage points. Results indicate that the protease product used in the current study marginally reduced the SID of AA for both SBM and field pea. However, the protease product can be beneficially included in diets based on SBM or field pea for broilers to enhance their AMEn values. The response to the protease on the AMEn was consistent regardless of the protein source in the diet, implying that the protease used in this study has similar positive impact on energy availability in both field pea and SBM.