بررسی اثر عمل آور ی به روش انباشت بر ارزش غذایی و ایمن سازی کود بستر جوجه گوشتی

This study was conducted to investigate the effects of deep-stacking process, with different moisture contents, on the nutrients concentration and disinfection of broiler litter (BL). Broiler litter was provided from poultry house of Animal Science Research Institute (Karaj, Iran) and deep-stacked with three moisture levels (15, 25 or 35%), using 11.5ا1ا m containers, prepared with still frame and nylon sheet. Daily temperature of the deep-stacked BL at different depths (30, 60 and 120 cm) was recorded during 21 days. At the finite temperature point, representative samples were taken from different depths. The raw BL and deep-stacked samples were studied for microbial contents including total count, and specific microorganisms (Salmonella, Escherichia coli and Coliformes) and chemical compositions. Data were statistically analised, using a split plot design. The maximum temperature (55.7 and 51.6 C) was recorded, in 9th days of starting, for 30 and 60cm depths, respectively. But the maximum temperature (45.1 C) was lower for 120cm depths in 12th day; thereafter it showed a reduction trend. The temperature was affected by moisture contents in different depths (P<0.05), during days 1-4 and 9-12. An interaction effect of moistureاdepths was found on the variation of temperature. The bacterial count, Coliforms and Escherichia coli (E. coli) were decreased as compared with non processed samples (P<0.05) with the exception of the 30cm-depth at 15% moisture and 120cm-depth at 25% moisture. There was not any Coliforms count in processed BL at depth 30cm with 25% moisture and at depth 30 and 60cm with 35% moisture. The E. coli. populations were zero at the different depths of deep-stacked BL with 35% moisture. The Salmonella count was zero at depths 30 and 60cm with 25 and 35% moisture contents and at depth 120cm with 35% moisture content. Deep-stacking BL, with 25 and 35% moisture increased temperature and reduced organic matter and crude protein but increased NDF and ADF (P<0.05). Protein fractions were also affected by the deep stacking with decreasing fractions A and B1 but increasing B2, B3 and C. Fractions B1, B2, B3 and C were affected by depths, moisture and their interactions but fractions A was affected only by the moisture levels. Overall, deep-stacking BL with 35% of moisture for 9 days (to reach the final destined temperature of 60 C) decreased the total count bacteria and other Coliforms and eliminated the pathogenic bacteria (E. coli and Salmonella). Key words: broiler litter, deep-stacking, pathogenic bacteria