Performance of laying hens fed wheat, wheat-barley or wheat-barley-wheat bran based diets supplemented with xylanase

Two experiments were conducted to study the response of laying hens to a commercial enzyme preparation (Safizyme XP20) containing 70 000 IU g(-1) xylanase. In the first experiment, 270 laying hens (ISA Brown), aged 28 wk, were fed basal diets of wheat (W), wheat-barley (WB) or wheat-barley and wheat bran (WBB) without xylanase, or supplemented with 1400 W xylanase kg(-1) in 3 x 2 factorial arrangement. In the second experiment, 180 ISA Brown laying hens, aged 28 wk, were assigned to 2 x 2 factorial arrangement and fed wheat-based diets containing 2753 or 2653 kcal metabolizable energy (ME) kg(-1) without xylanase, or supplemented with 1400 IU xylanase kg(-1). Egg production (% hen-day), egg weight, egg mass, feed conversion ratio and changes in body weight were recorded for 12 wk. The effects of xylanase on true metabolizable energy (TME) values of wheat, barley and wheat bran were determined using roosters. Layers fed W-, WB- or WBB-based diets had similar egg mass. The feed conversion ratio of layers fed the WBB-based diet was better (P less than or equal to 0.05) than that of the other groups. Xylanase improved (P less than or equal to 0.05) egg mass of layers fed W- or WB-based diets, but it did not affect the performance of hens fed the WBB-based diet. Low dietary ME significantly (P less than or equal to 0.05) reduced the performance of laying hens. Xylanase supplementation improved (P less than or equal to 0.05) egg production, egg mass and feed conversion ratio of layers fed the low energy diet. It did improve the feed conversion ratio of layers fed the high-energy diet. Addition of 1400 IU xylanase kg(-1) to the low-energy diet was equivalent to an increase of at least 100 kcal ME kg(-1). Xylanase increased (P < 0.05) the TME values by 5.2 and 2.44% for wheat and barley, respectively, and did not affect the TME value of wheat bran.