Ruminal Hydrolytic Enzymes Activity and In Vitro Gas Production Kinetics of Pelleted Leaves Mixture as Tannin Source: Acacia mangium Willd, Swietenia mahagoni, and Artocarpus heterophyllus

The objective of this study was to investigate the effect of feed pellet containing three leaves mixtures as tannin sources (Acacia mangium Willd, Swietenia mahagoni, and Artocarpus heterophyllus) on rumen fermentation parameters in vitro, especially on ruminal enzymes activity and gas production kinetics. Pelleted leaves were applied to substitute the use of concentrate in the diet (grass:concentrate, 60:40) with three substitution levels equal to tannin concentration at 0, 1, and 2 based on dry matter (DM). All dietary treatments were used as a substrate for in vitro fermentation by Menke and Steingass gas production method at 48 hours of incubation time. Fermentation medium and gas production after incubation were used to determine rumen hydrolytic enzymes activity and gas production kinetics. Data were analysed by one-way analysis of variance (ANOVA) and continued by Duncan's Multiple Range Test (DMRT). The application of pelleted leaves mixture as a tannin source of up to 2 could reduce the activity of amylase, CMC-ase, and protease significantly (P<0.05). β-glucosidase enzyme activity was decreased significantly at 2 tannin. Gas production from soluble fractions (a) was decreased significantly (P<0.05) but gas production from insoluble fraction (b), the gas production rate (c), and the amount of (a+b) fraction was not affected (P>0.05). The substitution of concentrate with pelleted leaves as tannin source could decrease in vitro rumen hydrolytic enzymes activity and the kinetics of gas production in terms of insoluble fraction. © 2023 American Institute of Physics Inc.. All rights reserved.