Effects of bacterial β-mannanase on apparent total tract digestibility of nutrients in various feedstuffs fed to growing pigs

OBJECTIVE: The objective of this study was to determine the effects of β-mannanase on metabolizable energy (ME) and apparent total tract digestibility (ATTD) of protein in various feedstuffs including barley, copra meal, corn, corn distillers dried grains with solubles (DDGS), palm kernel meal, sorghum, and soybean meal. METHODS: A basal diet was formulated with 94.8% corn and 0.77% amino acids, minerals, and vitamins and test diets replacing corn-basal diets with barley, corn DDGS, sorghum, soybean meal, or wheat (50%, respectively) and copra meal or palm kernel meal (30%, respectively). The basal diet and test diets were evaluated by using triplicated or quadruplicated 2×2 Latin square designs consisting of 2 diets and 2 periods with a total of 54 barrows at 20.6±0.6 kg (9 wk of age). Dietary treatments were levels of β-mannanase supplementation (0 or 800 U/kg of feed). Fecal and urine samples were collected for 4 d following a 4-d adaptation period. The ME and ATTD of crude protein (CP) in feedstuffs were calculated by a difference procedure. Data were analyzed using Proc general linear model of SAS. RESULTS: Supplementation of β-mannanase improved (p<0.05) ME of barley (10.4%), palm kernel meal (12.4%), sorghum (6.0%), and soybean meal (2.9%) fed to growing pigs. Supplementation of β-mannanase increased (p<0.05) ATTD of CP in palm kernel meal (8.8%) and tended to increase (p = 0.061) ATTD of CP in copra meal (18.0%) fed to growing pigs. CONCLUSION: This study indicates that various factors such as the structure and the amount of β-mannans, water binding capacity, and the level of resistant starch vary among feedstuffs and the efficacy of supplemental β-mannanase may be influenced by these factors.