The objective of this study was to evaluate the effect of dietary energy level reduction and xylanase inclusion on the performance and on intestinal mucosa morphometry of two- to six-week-old laying hens. In total, 400 Hy-line W36 laying hens were distributed according to a completely randomized design in 2 x 2 factorial arrangement (energy level x inclusion of xylanase), totaling four treatments with 10 replicates of 10 birds per experimental unit. The following treatments were evaluated: positive control (balanced diet); positive control + xylanase; negative control (diet with of 100 kcal ME reduction /kg); negative control + xylanase. Body weight, weight gain, feed conversion ratio, uniformity and livability were not influenced by diets with metabolizable energy reduction and xylanase inclusion; however, the addition of xylanase to the diets resulted in shallower crypts depth and greater villus:crypt ratio in the ileum. The energy reduction of the diet associated with the supplementation of xylanase did not influence performance, but increased the feed intake of 2- to 6-week-old laying hens and increased villus height in the ileum of 6-wk-old hens. Xylanase reduces crypt depth in the ileum of 6-week-old hens.
Body weight; crypt depth; energy reduction; flock uniformity; villus height
