Effect of adding an anaerobic fungal culture isolated from a wild blue bull (Boselophus tragocamelus) to rumen fluid from buffaloes on in vitro fibrolytic enzyme activity, fermentation and degradation of tannins and tannin‐containing Kachnar tree (Bauhinia variegata) leaves and wheat straw

Abstract

AbstractThe study investigated the effects of adding an anaerobic fungus (Piromyces sp FNG5; isolated from the faeces of a wild blue bull) to the rumen fluid of buffaloes consuming a basal diet of wheat straw and concentrates on in vitro enzyme activities, fermentation and degradation of tannins and tannin‐rich tree leaves and wheat straw. In experiment 1, strained rumen fluid was incubated for 24 and 48 h, in quadruplicate, with or without fungal culture using condensed tannin‐rich Bauhinia variegata leaves as substrates. In experiment 2, in vitro incubation medium containing wheat straw and different concentrations of added tannic acid (0–1.2 mg mL−1) were incubated for 48 h, in quadruplicate, with strained buffalo rumen fluid with or without fungal culture. In experiment 3, tolerance of the fungal isolate to tannic acid was tested by estimating fungal growth in pure culture medium containing different concentrations (0–50 g L−1) of tannic acid. In in vitro studies with Bauhinia variegata tree leaves, addition of the fungal isolate to buffalo strained rumen liquor resulted in significant (P < 0.01) increase in neutral detergent fibre (NDF) digestibility and activities of carboxymethyl cellulase (P < 0.05) and xylanase (P < 0.05) at 24 h fermentation. There was 12.35% increase (P < 0.01) in condensed tannin (CT) degradation on addition of the fungal isolate at 48 h fermentation. In in vitro studies with wheat straw, addition of the fungus caused an increase in apparent digestibility (P < 0.01), true digestibility (P < 0.05), NDF digestibility (P < 0.05), activities of carboxymethyl cellulase (P < 0.001), β‐glucosidase (P < 0.001), xylanase (P < 0.001), acetyl esterase (P < 0.001) and degradation of tannic acid (P < 0.05). Rumen liquor from buffaloes which had never been exposed to tannin‐containing diet had been found to have substantial inherent tannic acid‐degrading ability (degraded 55.3% of added tannic acid within 24 h of fermentation). The fungus could tolerate tannic acid concentration up to 20 g L−1 in growth medium. The results of this study suggest that introduction of an anaerobic fungal isolate with superior lignocellulolytic activity isolated from the faeces of a wild herbivore may improve fibre digestion from tannin‐containing feeds and degradation of tannins in the rumen of buffaloes. Copyright © 2005 Society of Chemical Industry