RESPIRABLE TISSUE DAMAGE IN BROILERS EXPOSED TO AEROSOL PARTICLES AND AMMONIA

摘要

Air within housing for broiler chickens has been shown to contain high concentrations of respirable aerosol (RACs) and noxious gases. Equipment to reduce these concentrations can be properly designed if threshold limits of contaminants are defined. Broiler chickens raised in laboratory chambers were exposed to treatments of population density and air recirculation rates to create different airborne environments. In order to assess the harm to broiler’s respiratory system caused by these treatments, various methods were used including measuring broiler weight gain, feed conversion and mortality; examination of tissue by an avian pathologist; and a new test procedure which measures bursting pressure of the respiratory system. Results indicate that broilers exposed to mean RACs ranging from 9.5 to 46.6 particles/mL did not experience reduction in mean weight gain or an excessive increase in mortality and feed conversion over a 7-week growout period. Broilers grown during a treatment where mean RAC and ammonia concentration were highest (46.6 particles/mL and 24 ppm) had the highest mean body weights and lowest feed conversion and mortality rates. Mean lung bursting pressures (BPs) were not significantly different between treatments indicating that the treatment levels of air contamination had little effect on respiratory tissue