Effects of energy levels of diet and β-mannanase supplementation on growth performance, apparent total tract digestibility and blood metabolites in growing pigs

The present study investigated the effects of energy levels of diet and β-mannanase supplementation on growth performance, apparent total tract digestibility (ATTD) of nutrients, blood metabolites and fecal volatile fatty acids (VFAs) and ammonia-N emission in growing pigs. A total of 192 grower pigs [average initial body weight (BW), 36.2 kg] were randomly allotted to 4 treatments on the basis of BW. There were 4 replicates in each treatment with 12 pigs per replicate. Pigs were fed diets containing 13.7 or 14.0 MJ/kg metabolizable energy (ME) and 0 or 400 units (U) of β-mannanase/kg in a 2 × 2 factorial arrangement. The experimental diets were fed in a meal form for 42 d. The final BW, average daily gain (ADG) and gain:feed (G:F) of pigs fed diets supplemented with β-mannanase were greater (P < 0.05) than in pigs fed diets without (0 U/kg) β-mannanase. In addition, final BW, ADG and G:F of pigs fed 14.0 MJ/kg ME diets were greater (P < 0.05) than in pigs fed 13.7 MJ/kg ME diets. The ATTD of dry matter (DM), gross energy (GE), mannose and galactose of pigs fed diets supplemented with β-mannanase was greater (P < 0.05) than in pigs fed diets without β-mannanase. The blood glucose concentration was increased (P < 0.05) in pigs fed diets containing β-mannanase or 14.0 MJ/kg ME diets. The energy level of diet and β-mannanase supplementation had no effect (P > 0.05) on fecal volatile fatty acids and ammonia-N concentrations. Moreover, final BW, ADG, G:F, ATTD of DM, GE, mannose and galactose and blood glucose concentration were not different (P > 0.05) among pigs fed 13.7 MJ/kg ME diet with β-mannanase and 14.0 MJ/kg ME diet without β-mannanase. These results indicate that dietary supplementation of 400 U of β-mannanase/kg had potential to improve the growth performance, ATTD of nutrients and may provide the equivalent of 0.36 MJ/kg of ME to growing pig diets.