<p><em>Since rice straw is seasonal and low quality roughage, </em><em>thus, </em><em>a supplementation for it is needed. Lamtoro lea</em><em>f</em><em> meal (LLM) and soybean meal (SBM), hav</em><em>e</em><em> both soluble and bypass protein</em><em>, </em><em>so it enough potential to supply nutrients </em><em>to</em><em> optimize of rumen microbes and improv</em><em>e </em><em>animal performance. Supplementation with LLM or SBM significantly increase</em><em>d</em><em> dry matter, organic matter, crude protein and crude fiber intake (</em><em>P</em><em>&lt;0.05). This fact showed that LLM or SBM supplementation made an </em><em>improvement</em><em> of rumen fermentation by microbes. Comparison between LLM and SBM to basal diet clearly showed that basal diet </em><em>wa</em><em>s the lowest (</em><em>P</em><em>&lt;0.0</em><em>5</em><em>) nutrien</em><em>t</em><em> intake and nutrien</em><em>t</em><em> digestibility, however, the animal fed basal diet degraded crude fiber was not </em><em>affected</em><em>. It </em><em>has been shown that</em><em> sup</em><em>p</em><em>lementation with lamtoro lea</em><em>f</em><em> meal or soybean meal </em><em>we</em><em>re palatable, fermentable and reasonably digestible. </em><em>Therefore, the</em><em> use</em><em> of these feedstuffs</em><em> as supplement to rice straw </em><em>are</em><em> strongly recommended. </em></p><p><em> </em></p><p><strong><em>Key words</em></strong><em> : </em><em>concentrate</em><em>, PO beef cattle, </em><em>performance, </em><em>digestibility</em></p>