Abbreviation Key: FE = feed efficiency; FI = feed intake; GLM = General Linear Model; SCWL = Single Comb White Leghorn. ABSTRACT A total of 640 22-wk-old pullets (Shaver SX 288) housed four birds per cage in 40 experimental units (four cages per unit), were randomly assigned eight experimental diets in a 2 × 2 × 2 factorial arrangement. The treatments consisting of two grain sources (wheat and rye) two levels each of crude enzyme preparation (0 and 0.1% Roxazyme ® G), and added inorganic

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... rus (0 and 0.105%) were fed for five 4-wk periods. At 42 wk of age, 40 individually caged layers were fed the experimental diets with 0.3% chromic oxide (5 individual birds per treatment) to determine AME n and available P. Plasma P and Ca were also determined. Egg production, feed intake (FI), egg weight, feed efficiency (FE), and specific gravity of eggs were significantly (P ≤ 0.05) affected by the experimental periods. Hens fed wheat-based diets had higher (P ≤ 0.05) tibia ash (54.3 vs 52.5%), excreta dry matter (22.0 vs 17.7%), and eggshells with ≥ 1.080 specific gravity (93.5 vs 89.9%) than birds fed rye. Enzyme supplementation significantly improved AME n (P ≤ 0.01) and FE by 6.2 and 3%, respectively. Egg production increased numerically from 87.6 to 90.1%. Inorganic P supplementation significantly increased egg production (P ≤ 0.01), FI, FE, and AME n (P ≤ 0.05) by 4.4, 2, 3, and 2.8%, respectively, but significantly (P ≤ 0.05) decreased the proportion of eggs having a specific gravity ≥ 1.080 from 92.8 to 90.6%. The enzyme and inorganic P supplementation had no effect on tibia ash content and total plasma Ca and P. Rye can be used in layer rations yielding satisfactory performance when fed with a fungal crude enzyme preparation high in pentosanase/xylanase activity. (