The effect of protease and nonstarch polysaccharide enzymes on manure odor and ammonia emissions from finisher pigs

A 2 x 2 factorial experiment was conducted to investigate the effect of dietary protease (0 and 200 mg/kg) and xylanase (0 and 200mg/kg) in reducing manure odor and NH3 from finisher pigs. Sixteen pigs were assigned to 1 of 4 dietary treatments, (i) basal diet, (ii) basal diet + xylanase, (iii) basal diet + protease, or (iv) basal diet + xylanase + protease, for 24 d. The manure samples from pigs offered diets containing protease showed increased (P < 0.05) molar proportions of isobutyric acid, isovaleric acid, valeric acid, and branched-chain fatty acids in contrast to pigs offered diets without protease supplementation. The pigs offered diets with xylanase inclusion had reduced (P < 0.05) manure odor emissions compared to pigs offered diets without xylanase supplementation [ 598 vs. 1306 European odor units (OuE)/m(3)]. Pigs offered protease-supplemented diets alone had significantly higher NH3 emissions compared to basal fed pigs. However, NH3 emissions were reduced when protease was combined with xylanase. In summary, this study indicates that protease supplementation increased protein-derived VFA in manure and also increased manure NH3 emissions when offered singularly. Consumption of diets containing xylanase reduced manure odor emissions.