Atmospheric ammonia inhibits broiler performance. Quantified effects are based on older genetic stock with a BW of 2,000 g at 7 wk. In contrast, modern genetic stock reaches 3,200 g at 7 wk of age. To assess the impact on present day broilers, 2 trials were conducted exposing male broilers to graded levels (0, 25, 50, and 75 ppm) of aerial ammonia…