Two experiments were conducted to evaluate the effect of alum on ammonia emission, live performance, and health of
broilers. In experiment 1, the effect of alum (0, 2, and 4%) supplementation on the emission of ammonia was measured. The
effects of alum-treated litter and stocking density (12, 16, and 20 birds m-2) on the live performance and incidence of
footpad and hock dermatitis were investigated in experiment 2. Alum supplementation in chicken excreta significantly
decreased pH from 8.06 to 5.27 and 3.62 by 2 and 4% alum treatments, respectively. Ammonia emission rate was reduced
73.0 and 75.8% by 2 and 4% alum treatments, respectively. The suppressed litter urease activity was detected in 4% alum
treatment. Alum-amended litter (1 kg m-2) decreased atmosphere ammonia concentrations by 30% in broiler house. Alumamended
litter maintained a lower pH until 35 d of age. Body weight (BW) gain was decreased by alum treatment in the
period of 4-7 wk of age. Higher stocking density (20 birds m-2) increased BW gain in the first 3 wk of age but decreased BW
gain during the period of 4-7 wk of age. Neither alum nor stocking density treatments had a significant effect on feed
intake and feed efficiency. Alum-treated litter had no detrimental effect on the development of footpad and hock burns.
In contrast, high stocking density (20 bird m-2) increased the incidence of footpad and hock lesion. The result suggests
that the decreased litter pH and suppressed bacterial urease activity by alum treatment is responsible for the decreased
ammonia emission. At high stocking density, the increased litter moisture content should be responsible, at least partially,
for the development of footpad and hock lesions.