Potential of seaweed (Eucheuma cottonii) supplementation to reduce methane production, improve fermentation, and modulate the microbial composition of forages and crop by-products during in vitro rumen fermentation

Result showed that corn stalk produced the highest asymptotic gas, dry matter digestibility, shorted fermentation lag time, SCFA, metabolizable energy, and microbial crude protein. Corn stalk production the highest asymptotic (<i>p</i> < 0.001) methane gas, but had the lowest proportion of methane gas compared to total gas. Microbial analysis showed that rice straw without seaweed had the highest microbial diversity and evenness while rice straw with 8% seaweed group, exhibited lower methanogen abundance, increased <i>Rikenellaceae_RC9</i> gut group and <i>Ruminobacter</i>. Cornstalk was the most efficient forage in rumen fermentation, while <i>E. cottonii</i> supplementation modulated fermentation, enhanced microbial protein synthesis, reduced methane emissions, and altered microbial diversity. Therefore, corn stalks without seaweed is a highly effective crop-by product for ruminant nutrition offering better fermentation characteristic and energy yield.