The effect of benzoic acid concentration on nitrogen metabolism, manure ammonia and odour emissions in finishing pigs

A complete randomised block design experiment was conducted to investigate the effects of benzoic acid inclusion level on nitrogen (N) metabolism, and manure ammonia (NH3) and odour emissions in finishing pigs. Sixteen boars (64kg live weight±1.5kg) were assigned to one of four dietary treatments (T) varying in benzoic acid concentration: (T1) 0g benzoic acid/kg (as fed); (T2) 10g benzoic acid/kg; (T3) 20g benzoic acid/kg; (T4) 30g benzoic acid/kg. Animals were housed in individual metabolism crates and feed was provided ad libitum. All diets were formulated to have similar concentration of digestible energy and ileal digestible lysine with benzoic acid replacing wheat in the diet. There was a linear decrease in NH3 emission (P0.05) of benzoic acid on odour concentration. Urinary nitrogen (N) excretion, total N excretion and the urinary:faecal N ratio were linearly reduced (P