Effects of dietary crude protein on growth, ammonia concentration and litter composition in broilers

An experiment was conducted to reduce NH₃ emissions and N content of broiler litter by reducing dietary protein (CP) levels and supplementing with amino acids without adversely affecting bird performance. The results would suggest that reducing CP (and lysine) below 241 g/kg (13.7 g/kg lysine) in the diets fed during the first 3 weeks may slightly reduce feed:gain and therefore may not be advisable. During the period 22 to 43 days there were no significant differences in weight gain and body weight at six weeks of age when reducing the crude protein content from 215 g/kg (11.5 g/kg lysine) to 196 g/kg (11.3 g/kg lysine) but food intake and feed:gain ratio increased. However, reducing CP did cause equilibrium NH₃ gas concentration and litter N to decline by 31% and 16.5%, respectively. Both of these advantages will improve air quality within the housing facility and possibly reduce heating costs during winter associated with higher ventilation rates required to reduce elevated ammonia gas concentrations.