Apparent component digestibility and manure ammonia emission in finishing pigs fed diets based on barley, maize or wheat prepared without or with exogenous non-starch polysaccharide enzymes

Abstract A 3×2 factorial-design experiment was conducted with finishing pigs to examine the effect of cereal type (barley, maize or wheat) and a non-starch polysaccharide enzyme supplement (endo-1,3(4)-β-glucanase and endo-1,4-β-xylanase) on apparent nutrient digestibility, nitrogen (N) balance and manure ammonia (NH 3 -N) emission. Diets were formulated to contain similar concentrations of digestible energy and lysine, sulphur amino acids, threonine and tryptophan. After a 14-day dietary adaptation period, urine and faeces were collected from 24 boars (four boars per treatment, 61 kg initial live weight), housed in metabolism crates. NH 3 -N emission was measured over 10 days using a laboratory scale procedure. The procedure consisted of a sealed vessel containing 2 kg slurry, vacuum pump and three impingers in series per sample. The coefficient of total tract apparent digestibility (CTTAD) of dry matter (DM), gross energy (GE) and N digestibilities were higher in wheat-based diets than maize- or barley-based diets (P 3 -N emission was affected by a cereal×enzyme interaction (P 3 -N emission in the barley-based diet and decreased NH 3 -N emission in the wheat-based diet. In conclusion, ammonia emission from the manure of finishing pigs is affected by the use of cereal types differing in the concentration of β-glucan and arabinoxylans and exogenous non-starch polysaccharide enzyme supplementation.