Department of Animal Science, Faculty of Agriculture, University of Tehran, P.O. Box 4111, Karaj, I.R. Iran.
Department of Animal and Marine Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), P.O. Box 14965/161, Tehran, I.R. Iran.
The effects of non-starch polysaccharide (NSP) content of wheat and xylanase supplementation (XS) of the diet, on intestinal enzyme activity (amylase, aminopeptidase and lipase), fat digestibility and ileal viscosity of laying hens has been studied. Two hundred forty Hy-Line W-36 layer from 20 to 25 week of age were studied under a factorial experiment (4×2) in completely randomized design with 8 treatments including four levels of wheat (0, 23, 46 and 69%) corresponding to a dietary xylose content of 1.9, 2.1, 2.3 and 2.5% and two levels of xylanase (none or added at the dosage recommended by the supplier). Each treatment was replicated five times each with six hens. Wheat inclusion in the diet increased amylase and lipase activity in the duodenum and jejunum, respectively (P<0.001). Wheat inclusion, increased ileal viscosity while adding xylanase to diet, reduced it (P<0.001). Fat digestibility was decreased by wheat increment levels (P<0.001). The pH of the digesta content in different segments of gastro-intestinal tract (GIT) was not affected by wheat levels or XS, except for cecum that decreased with increasing the level of wheat. Relative weight and length of duodenum,
jejunum and ileum were not affected by dietary treatment. Results suggested that wheat inclusion at high
levels increased endogenous enzyme activity but could not alleviate the adverse effect of NSP content of
diet on fat digestibility. Keywords: Fat digestibility; Intestinal enzymes; Laying hen; Wheat; Xylanase