Effect of atmospheric ammonia on bovine lung

Abstract

The effect of atmospheric ammonia on bovine lung was investigated in 3 experiments by means of bronchio-alveolar lavage (BAL). Cattle were placed in rooms simulating live export conditions and atmospheric ammonia was monitored throughout. Bronchio-alveolar lavage was performed 4 days before the cattle were placed in rooms and immediately after they left the rooms. The cattle were introduced to experimental diets 5 days before the first BAL was performed. In all experiments, wood shavings were used as bedding and, in room 2, these were mixed with gypsum (2:1) and partially changed every 2-3 days. In experiment 1, 10 Angus cross heifers were fed lucerne cubes diets (2.25% of liveweight (LW)) with 5 placed in each simulation room for 9 days. Atmospheric ammonia was significantly (P<0.05) higher in room 1 (42.3 ± 2.8 ppm) than in room 2 (22.0 ± 1.6 ppm). In experiments 2 and 3, 3 groups of 4 Angus cross heifers were used. They were fed (all at 3% of LW) either a basic export diet (BD) or a basic diet containing CaCl₂ (BD + CaCl₂). Two groups were kept in the simulation rooms for 12 days, and a third group was kept outdoors in a sand yard. In experiment 2, the animals in room 1 were fed BD while the animals in room 2 and outdoors were fed the BD + CalCl₂. Atmospheric ammonia was significantly different (P<0.05) among the 3 groups, and the values were 16.8 ± 0.68, 9.4 ± 0.34 and 0 ± 0 ppm, respectively, for rooms 1 and 2, and outdoors. In experiment 3, animals in room 1 and outdoors were fed the BD while the animals in room 2 were fed the BD + CalCl₂. Atmospheric ammonia values were18.6 ± 0.6, 10.6 ± 0.3 and 0 ± 0 ppm, respectively, for rooms 1 and 2, and outdoors. In experiments 1, there was a significant increase in total white cell and mononucleated cell counts (P<0.05) on the BAL samples performed after the animals left the rooms. There were no changes on BAL samples in either experiment 2 and 3. The recommended time-weighted average safety levels for atmospheric ammonia for humans (25 ppm) were exceeded on a number of occasions in both rooms in experiment 1. On the other hand, atmospheric ammonia did not exceed 25 ppm in either experiment 2 or 3. The dust levels in both rooms and sand yard were very low, therefore, ammonia was the most logically attributable cause for the irritation developed by the animals in experiment 1.