Impact of inulin supplementation on mitigating ruminal emissions of methane

Ruminal fermentation of feed leads to methane production and wastes feed energy. Appropriate feed additives have shown to reduce ruminal methane production. Accordingly, it is important to identify compounds as feed additives to alter ruminal fermentation patterns to improve feed efficiency as well as reduce methane production. This experiment aimed to investigate the effect of inulin additive (as a prebiotic compound) on ruminal fermentation, feed digestibility, and methane production by in vitro techniques. Experimental treatments included control treatment (basal diet), 2% (w/w) inulin (basal diet with 2% inulin), and 4% (w/w) inulin (basal diet with 4% inulin). Gas production at 2, 4, 6, 12, 24, 48, 72, and 96 h of incubation as well as dry matter (DM) and organic matter digestibility (OMD) was determined. Also, some rumen fermentation parameters including pH, ammonia–nitrogen, volatile fatty acids, and methane production were determined. Per our findings, the addition of inulin increased gas production except for the first 2 h of incubation (p < 0.05). The addition of inulin changed the profile of ruminal volatile fatty acids (p < 0.05) so that the addition of inulin increased the concentration of propionic acid (p < 0.05). The addition of inulin also reduced lactic acid concentration (p < 0.05). Rumen ammonia–nitrogen was reduced by the addition of inulin (p < 0.05), which could indicate an improvement in rumen nitrogen metabolism. Addition of inulin reduced methane production from feed fermentation by rumen microbiota (p < 0.05). Dry matter and organic matter digestibility increased with the addition of inulin (p < 0.05). According to the results, the use of inulin (as a prebiotic of plant origin) not only does not disrupt ruminal fermentation but also improves the fermentation process, increases feed digestibility, and most importantly reduces methane excretion, which can increase production efficiency.