Effect of an acidifying diet combined with zeolite and slight protein reduction on air emissions from laying hens of different ages

The objectives of the study were to evaluate the effectiveness of a reduced-emission (RE) diet containing 6.9% of a CaSO4-zeolite mixture and slightly reduced CP to 21-, 38-, and 59-wk-old Hy-Line W-36 hens (trials 1, 2, and 3, respectively) on egg production and emissions of NH3, H2S, NO, NO2, CO2, CH4, and non-CH4 total hydrocarbons as compared with feeding a commercial (CM) diet. At each age, 640 hens were allocated, randomly to 8 environmental chambers for a 3-wk period. On an analyzed basis, the CM diet contained 18.0, 17.0, and 16.2% CP and 0.25, 0.18, and 0.20% S in trials 1, 2, and 3, and the RE diet contained 17.0, 15.5, and 15.6% CP and 0.99, 1.20, and 1.10% S in trials 1, 2, and 3. Diets were formulated to contain similar Ca and P contents. Average daily egg weight (56.3 g), average daily egg production (81%), average daily feed intake (92.4 g), and BW change (23.5 g), across ages, were unaffected by diet (P > 0.05) over the study period. Age effects were observed for all performance variables and NH3 emissions (P < 0.05). In trials 1, 2, and 3, daily NH3 emissions from hens fed the RE diets (185.5, 312.2, and 333.5 mg/bird) were less than emissions from hens fed the CM diet (255.1, 560.6, and 616.3 mg/bird; P < 0.01). Daily emissions of H2S across trials from hens fed the RE diet were 4.08 mg/bird compared with 1.32 mg/bird from hens fed the CM diet (P < 0.01). Diet (P < 0.05) and age (P < 0.05) affected emissions Of CO2 and CH4. A diet effect (P < 0.01) on NO emissions was observed. No diet or age effects (P > 0.05) were observed for NO2 or non-CH4 total hydrocarbons. Results demonstrated that diet and layer age influence air emissions from poultry operations.