Ocular responses to ammonia in broiler chickens

In two trials, 60 male commercial broilers were placed in each of eight environmentally controlled chambers receiving 0, 25, 50, or 75 ppm aerial ammonia from 1 to 28 days. Birds exposed to 25 ppm (lower concentration) ammonia gas developed ocular abnormalities but at a slower rate when compared with birds exposed to 50 and 75 ppm (higher concentrations). Birds exposed to higher concentrations also developed more severe lesions. With little atmospheric ammonia present after 28 days of the grow-out stage, the corneas indicated signs of healing. Lymphocytes and heterophils were seen in the iris at 49 days in ammonia-exposed birds even when ammonia exposure was terminated at 28 days. The lower ammonia concentrations resulted in abnormalities that were slight when compared with those seen at the higher ammonia concentrations. As measured by the incidence of inflammatory infiltrates in the trachea, lung, and air sacs, respiratory tract tissues did not appear to be affected by any tested level of aerial ammonia. The findings in this investigation represent the first report indicating that ammonia-induced uveitis in chickens clears rapidly after exposure to ammonia ceases.