The objective of this study was to determine the effect of dry medicinal plants (wormwood, chamomile, fumitory and mallow) and dietary substrates containing a mix of the plants on the end products of in vitro ruminal and intestinal fermentation, rumen protozoan population and ruminal antioxidant capacity of sheep. The experiment consisted of fermentations with the four plants used individually as the sole substrate and fermentation of a mix of medicinal plants (Plants): meadow hay:barley grain (MH:B), 700/300 w/w and Plants:MH:B, 100/600/300 w/w/w. The experiment was conducted using the in vitro gas production technique (IVGPT) with 35 ml of buffered inocula and approximately 250 mg (DM basis) of substrate incubated for 24 hr at 39°C in anaerobic conditions. Quantitative analyses of the bioactive compounds by ultra-high-resolution mass spectrometry in Plants identified three main groups: flavonoids (22 mg/g DM), phenolic acids (15 mg/g DM) and alkaloids (3 mg/g DM). The total antioxidant capacity (TAC) of the plant extracts and rumen fluid was analysed using a ferric reducing antioxidant power assay. The values of total and individual short-chain fatty acids, acetate:propionate ratio, pH and total gas production were significantly affected by the single plant substrates and inocula (p < .001). Apart from these parameters, the values of ammonia N, methane production and total gas produced were decreased in Plants:MH:B in comparison with MH:B (p < .001). A positive correlation was recorded between total polyphenols content and TAC of plant extracts (R2 = .778, p < .001). The counts of the total ciliate protozoan population in rumen fluid after 24 hr of fermentation were not significantly different (p > .05). Results suggest that the dietary substrate containing the medicinal plant mix possessed strong ruminal antioxidant capacity, had the potential to reduce methane emission and ammonia concentration and caused desirable changes in the gastrointestinal ecosystem.
Keywords: antioxidant capacity; bioactive compounds; ciliated protozoa; methane production; ruminal fermentation parameters.
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