Abstract
1. Excreta from broiler chickens, when sterilised at 121 °C for 20 min, released little ammonia gas after incubation at 33 °C for 24 h. 2. Addition of thiopeptin to fresh excreta decreased ammonia production after incubation. Caprylohydroxamic acid did not have such an effect. 3. Dietary additions (100 mg/kg) of thiopeptin or zinc bacitracin resulted in decreased ammonia gas production from incubated fresh excreta. Similar addition of caprylohydroxamic acid did not decrease ammonia production. 4. Dietary supplements of thiopeptin (2.5 mg/kg) or zinc bacitracin (20 mg/kg) resulted in somewhat decreased ammonia production from incubated fresh excreta.