The role of monoammonium glycyrrhizinate as a methane inhibitor to limit the rumen methane emissions of Karakul sheep

Methane (CH₄) from ruminant production systems produces greenhouse gases that contribute to global warming. Our goal was to determine whether monoammonium glycyrrhizinate could inhibit CH₄ emissions over the long term without affecting animal performance and immune indices in Karakul sheep. This study aimed to assess the effects of medium−term (60 days) addition of monoammonium glycyrrhizinate on growth performance, apparent digestibility, CH₄ emissions, methanogens, fibre-degrading bacteria and blood characteristics in Karakul sheep. Twelve male Karakul sheep (40.1 ± 3.59 kg) with fistula were randomly divided into two groups (n = 6): the Control group received a basal diet + the same volume of distilled water (30 ml) and the Treatment group received a basal diet + 8.75 g/kg monoammonium glycyrrhizinate injected via fistula. The adaptation stage was 15 days, and the measurement stage was 60 days. The sampling during the measurement stage was divided into two stages, stage I (1 ∼ 30 d) and stage II (31 ∼ 60 d). The results showed that monoammonium glycyrrhizinate significantly reduced the relative abundance of Bacteroides caccae, daily CH₄ emission and protozoa population, significantly increased the relative abundance of Lachnospiraceae bacterium AD3010, Lachnospiraceae bacterium FE2018, Lachnospiraceae bacterium NK3A20, Lachnospiraceae bacterium NK4A179 and Lachnospiraceae bacterium V9D3004 in stage I (P < 0.05); significantly increased the relative abundance of Lachnospiraceae bacterium AD3010, but significantly decreased the relative abundance of Lachnospiraceae bacterium NK4A179 and Lachnospiraceae bacterium C6A11 in stage II (P < 0.05). Therefore, monoammonium glycyrrhizinate could be used as a CH₄ inhibitor to limit the rumen CH₄ emissions of Karakul sheep in short−term period (30 days) without affecting the growth performance, fibre digestibility and blood parameters.