Turmeric rhizomes reduced <i>in vitro</i> methane production and improved gas production and nutrient degradability

Abstract

The present study aimed to evaluate the effect of dry turmeric rhizomes on <i>in vitro</i> biogas production and diet fermentability. Turmeric rhizomes were included at gradually increased levels: 0, 0.5, 1, 1.5 and 2% of a diet containing per kg dr matter (DM): 500 g concentrate feed mixture, 400 g berseem hay and 100 g rice straw, and incubated for 48 h. Gas chromatography-mass spectrometry analysis showed that <i>ar</i>-turmerone, <i>α</i>-turmerone and <i>β</i>-turmerone were the major bioactive compounds in the rhizomes. Turmeric rhizomes increased (<i>p</i> < 0.01) asymptotic gas production (GP) and rate and lag of CH₄ production and decreased (<i>p</i> < 0.01) rate of GP, lag of GP, asymptotic CH₄ production and proportion of CH₄ production. Turmeric rhizome administration linearly increased (<i>p</i> < 0.01) DM and fiber degradability and concentrations of total short-chain fatty acids, acetic and propionic acids and ammonia-N and quadratically (<i>p</i> < 0.05) decreased fermentation pH. It is concluded that including up to 2% turmeric rhizomes improved <i>in vitro</i> ruminal fermentation and decreased CH₄ production.