Nitrogen retention, energy, and amino acid digestibility of wheat bran, without or with multicarbohydrase and phytase supplementation, fed to broiler chickens1

The study was conducted to determine the effects of multicarbohydrase (MC) preparation (700 U α-galactosidase, 2,200 U galactomannanase, 3,000 U xylanase, and 22,000 U β-glucanase per kg of diet) and phytase (Phy, 500 FTU per kg of diet) supplementation on the nutritive value of wheat bran (WB) in broiler chicks. Trial 1 determined retention of nutrients and apparent metabolizable energy corrected by nitrogen (AMEn). One reference diet (RD) protein-free (85% corn based) was fortified to determine the WB nutrient retention coefficient. Trial 2 determined standardized ileal digestibility (SID) of AA, when pancreas and liver were weighed. An additional group of bird was fed with an RD with 5% casein-corn starch diet, fortified with vitamins and minerals to quantify the endogenous fraction and determine SID of AA. For each trial, the test diets were made by mixing RD and WB 7:3 (wt/wt) and fed without or with MC or Phy or combination. Male broilers (Cobb 500), 245 d old, were allocated to five treatments to give seven replicates (seven birds/cage). The birds were fed a commercial diet from day 0 to10 followed by Trial 1 diets from day 11 to 18 and finally Trial 2 diets from day 19 to 21. Excreta samples were collected on days 15-18 and all birds were slaughtered on day 21 for ileal digesta. There was an interaction (P < 0.05) between MC and Phy on retention of DM, N, P, and AMEn. An interaction (P < 0.05) was also observed on SID of Arg, His, Leu, Lys, Phe, Thr, Val, Asp, Cys, Glu, and Ser. Responses of MC plus Phy supplementation were higher (P < 0.05) on overall SID of AA by 6.05% (75.18 to 94.26%), compared with responses for MC (2.35%; 72.04 to 88.97) or Phy (3.46%; 73.27 to 92.13). Liver and pancreas weights were affected (P < 0.05) by the single MC supplementation. The MC and Phy combination may be an effective strategy to improve AA utilization of WB in broiler chickens.