Stacking broiler litter to reduce natural hormones

Abstract

Estrone, 17β-estradiol, and testosterone are naturally occurring hormones excreted in broiler litter. With some potential for environmental concern from the hormones, understanding management practices effect on hormone concentrations is beneficial for the poultry industry. As the amount of hormones potentially introduced into the environment is directly related to the concentration at the time of land application, the purpose of this study was to investigate hormone dynamics in stacked broiler litter during the storage period before removal from the farm and/or land application. Stack temperatures and hormones concentrations were monitored at 15, 45, 75 cm, and 105 cm (measured from the stack bottom) in 6 different on-farm stack houses over 4 or 8 wk. Significant differences in temperature were determined by height and by stack. Stack temperatures during the first 4 wk ranged from 41.5°C to 54.5°C, and all stacks reached maximum temperature by 7 D. Highest temperatures were observed at the 45-cm or 75-cm height. Average stack temperatures correlated with the ambient temperature. Hormone concentration did not vary with height within each house. In 5 of the 6 stack houses, the concentrations of 17β-estradiol and/or testosterone significantly decreased after stacking for 4 or 8 wk (35 to 64%) with only one house showing a significant decrease in estrone concentration (72% in 4 wk). The percent change of estrone and 17β-estradiol mineralization during the first 4 wk was negatively correlated with the 7-D temperature of the pile (r2 = 0.80), indicating that the high temperatures observed during stacking may inhibit estrogen mineralization. In this study, hormone degradation decreased with high temperatures. Therefore, stack management favoring at least a period of low temperatures may help promote mineralization of these hormones and reduce any potential for introduction into the surrounding environment.