Effect of cereal type and exogenous enzyme supplementation in pig diets on odour and ammonia emissions

A 2 x 2 factorial experiment was conducted to investigate the interaction between cereal type (wheat vs. barley) and exogenous enzyme supplementation (with or without) on odour concentration and ammonia emissions in grower-finisher pigs. The enzyme supplement used contained Endo-1, 3 (4)beta-glucanase (EC 3.2.1.6) and Endo-1, 4-beta-xylanase (E.C 3.2.1.8). The diets were formulated to contain similar levels of digestible energy and lysine. The experimental treatments were as follows: (1) wheat-based diet, (2) wheat-based diet containing a beta-glucanase and beta-xylanase mixed enzyme supplement, (3) barley-based diet and (4) barley-based diet containing a beta-glucanase and beta-xylanase mixed enzyme supplement. The diets were offered to the pigs for 4 weeks and this was repeated 4 times (n = 4). Odour and ammonia emissions were measured on days 9, 11, 14, 16, 21 and 23 of each experimental period. Odour samples were collected in 20-litre Nalophan bags and analysed for odour concentration using an ECOMA Yes/No Olfactometer. Ammonia concentrations were measured using Drager tubes. There was a cereal x enzyme interaction in odour emission rates (P < 0.05) and in ammonia emissions (P < 0.01). The addition of an enzyme supplement increased odour emissions and had no effect on ammonia emissions in the barley-based diet. The enzyme supplementation had no effect on odour but decreased ammonia emissions in the wheat based diet. (c) 2007 Elsevier B.V. All rights reserved.