The present invention relates to a microorganism having an ability to produce propionic acid and a bulky feed composition comprising the same. The purpose of the present invention is to provide a bulky feed composition having excellent fatting promoting effects and a method for fatting a ruminant by using the bulky feed composition including rumen microbes. To this end, provided is a bulky feed composition including a microorganism having an ability to produce propionic acid separated from the ruminant stomach and Lactobacillus mucosae KCCM11440P.본 발명은 프로온산 생성능을 갖는 미생물 및 그를 포함하는 조사료 조성물에 관한 것이다.
