Investigation of xylanase, diet formulation method for energy, and choice of digestibility index marker on nutrient and energy utilization for broiler chickens and pigs.

The aim of this study was to investigate the growth performance and nutrient utilization responses of broiler chickens and the nutrient utilization of pigs to xylanase, experimental diet formulation method for energy (FME), and digestibility index marker (DIM). In Exp. 1, a total of 448 male broiler chickens were used in a randomized complete block design with body weight as a blocking factor. Seven dietary treatments were prepared in a 3 × 2 + 1 factorial arrangement with inclusion of sand, diatomaceous earth (DAE), or wheat bran (WB) as FME and without or with xylanase (26,400 unit/kg of diet) plus positive control. Each of chromic oxide and titanium dioxide were incorporated at 5 g/kg in diets. There were 8 replicate cages of 8 birds per cage. Birds were weighed on d 7, 14, and 21, and feed consumption were recorded. Excreta samples were collected from d 19 to 21. On d 21, birds were euthanized, and ileal digesta samples were collected. In Exp. 2, twenty-one barrows (initial body weight = 33.0 ± 0.3 kg), fitted with simple T-cannulas at the distal ileum, were used in a triplicate 7 × 2 incomplete Latin Square design with 7 dietary treatments, which were prepared by the same arrangement as in broilers, and 2 periods giving 6 replicates per diet. Fecal samples were collected on d 4 and 5, and ileal digesta samples were collected on d 6 and 7 of each period. In Exp. 1, the growth performance of birds was not affected by xylanase. There were interactions (P < 0.05) between xylanase and FME for apparent ileal digestibility (AID) of crude protein, His, Met, Thr, and Trp. Inclusion of xylanase decreased (P < 0.05) the AID of crude protein and Trp in sand diet and AID of His and Thr in DAE diet, but increased (P < 0.05) AID of Met in WB diet. Greater (P < 0.05) AID of energy and nutrients except Arg and Met was determined by Cr than Ti. In Exp. 2, there were interactions (P < 0.05) between xylanase and FME for AID of dry matter, energy, Arg, and Lys. Inclusion of xylanase decreased (P < 0.05) the AID of Lys in DAE or WB diet, but increased (P < 0.05) AID of Arg in sand diet and AID of energy in WB diet. The DIM type had no effect on responses in pigs. In conclusion, the efficacy of xylanase on ileal energy and amino acids digestibility depends on the choice of formulation method for energy in broilers and pigs, and digestibility index marker affects ileal digestibility in broilers.