Avoidance of atmospheric ammonia by domestic fowl and the effect of early experience

Abstract

An experiment was carried out to determine if broiler fowl, when given a free choice, would avoid ammoniated environments. The effect of rearing aerial environment on these preferences was tested subsequently during a similar free choice experiment. Firstly, each of four flocks of twelve 26-day-old female Ross broiler fowl, reared in fresh air, was placed in a preference chamber with access to four compartments. After an initial 4-day acclimatisation period, where no ammonia was provided, birds were given a free choice of 4, 11, 20 and 37 ppm atmospheric ammonia over a period of 16 days. Coloured panels in each of the compartments provided the birds with a secondary cue to associate with aerial environment. Ammonia/colour cue treatment was relocated to a different compartment every 4 days. Data collection occurred during two periods that differed in light level: bright (100 lx) and dim (10 lx). The birds avoided the two higher ammonia concentrations, choosing to spend equal amounts of their time in 4 and 11 ppm during the bright phase. During the dim period, broiler fowl spent significantly more time in 4 ppm (light intensity and ammonia occupancy interaction: F 3,60 = 5.40; P = 0.002). Ammonia significantly affected compartment visit duration with back transformed mean visits of 37, 28, 20 and 15 min for 4, 11, 20 and 37 ppm, respectively (Wald statistic = 29.07; d.f. = 3; P < 0.001). Secondly, eight flocks of 12 female broiler fowl were exposed to either 2 or 19 ppm ammonia from 1 to 26 days of age. At 26 days, each flocks, was placed in a preference chamber with access to four compartments and kept at the same atmospheric ammonia concentration (2 or 19 ppm) during an acclimatisation periods of 4 days. Following acclimatisation, a 4-day test was conducted in which the birds were given a choice of compartments containing 4, 12, 20 and 37 ppm ammonia with colour cues. Birds again avoided the two higher ammonia concentrations ( F 3,15 = 8.54; P = 0.002) and there was no significant interaction between ammonia and previous exposure. Again there was an effect of ammonia on compartment visit duration (Wald statistic = 15.94; d.f. = 3; P = 0.001) but there was no significant interaction between ammonia and previous exposure. Broiler fowl avoid ammonia at concentrations commonly found on poultry units regardless of previous experience, suggesting it to be aversive at concentrations above approximately 10 ppm.