Effect of supplementation of exogenous β-glucans and enzymes on nutrient digestibility, manure odour and ammonia emissions from finisher boars

It was hypothesised that supplementation of an exogenous mixed-linkage (1 → 3), (1 → 4)-β-d-glucan to a wheat-based diet may beneficially modulate manure odour and ammonia emissions associated with intensive pig production, without depressing nutrient digestibility as has been observed with intact β-glucans. A complete randomised design experiment was conducted to investigate the addition of β-glucans and enzyme supplementation on nutrient digestibility, manure odour and ammonia emissions from finisher boars. Twenty boars (74.2 kg s.d. 5.6) were assigned to five dietary treatments (n = 4); (1) a basal wheat-based diet, (2) wheat-based diet + exogenous β-glucan, (3) wheat-based diet + exogenous β-glucan + enzyme, (4) barley-based diet and (5) barley-based diet + exogenous enzyme. The wheat-based diets containing β-glucans were formulated to contain comparable concentrations of total β-flucans with barley-based diets. The enzyme mix used contained both β-glucanase and β-xylanase. Inclusion of exogenous β-glucan to a wheat-based diet had no effect on digestibility of dry matter (P > 0.05), ash (P > 0.05), neutral detergent fibre (P > 0.05) or nitrogen (P > 0.05) compared with the basal wheat diet.Pigs offered the barley-based diets decreased manure ammonia emissions from 0 to 240 h (P < 0.05) and increased manure odour emissions (P < 0.05) compared with the basal wheat diet. In conclusion exogenous β-glucans did not effect nutrient digestibility, or beneficially influence manure ammonia emissions.