Effects of Urtica dioica, Matricaria chamomilla, and Vitex agnus-castus extracts on in vitro rumen fermentation in normal and following acidosis conditions

Abstract

The aim of this study was to investigate the effects of dry extracts of Urtica dioica, Matricaria chamomilla, and Vitex agnus-castus with high phenolic contents on rumen microbial fermentation as compared with those of monensin, a common ionophore antibiotic, using Rumen Simulation Technique (RUSITEC) under normal and acidosis conditions. The treatments were as follows: negative control (no additive), positive control (5 mg/d monensin), and extracts of U. dioica (500 mg/d), M. chamomilla (500 mg/d), and V. agnus-castus (500 mg/d). Neither the plant extracts nor monensin altered the ruminal pH under normal or acidosis conditions. All the treatments affected total volatile fatty acid (VFA) production, propionate production, and dry matter digestibility (DMD), regardless of the fermentation conditions. All three extracts increased (P<0.05) total VFA production similar to that observed with monensin (P<0.05). M. chamomilla and V. agnus-castus increased propionate production and DMD similar to that obtained with monensin (P<0.05). In contrast to the monensin treatment, all three extracts increased acetate production under normal conditions (P<0.05). Under acidosis conditions, acetate production remained unchanged in the U. dioica and V. agnus-castus treatments, as well as in the monensin treatment. Under both conditions, the acetate-to-propionate (A:P) ratio decreased only in the monensin treatment (P<0.05). U. dioica and M. chamomilla had antiprotozoal effects (P<0.05) similar to those of monensin, regardless of the condition. The NH3-N concentration declined only in the V. agnus-castus treatment under acidosis conditions (P<0.05). Similar to the monensin treatment, lactate concentrations remained unchanged in the V. agnus-castus treatment under both conditions. In conclusion, plant extracts stimulated fermentative activity of rumen microorganisms under normal and acidosis conditions. Although they did not improve ruminal pH, U. dioica and V. agnus-castus extracts had more favorable effects on some fermentation parameters under acidosis conditions.