Use of Lysozyme as a Feed Additive on In vitro Rumen Fermentation and Methane Emission

This study was conducted to determine the effect of lysozyme addition on in vitro rumen fermentation and to identify the lysozyme inclusion rate for abating methane (CH₄) production. An in vitro ruminal fermentation technique was done using a commercial concentrate to rice straw ratio of 8:2 as substrate. The following treatments were applied wherein lysozyme was added into 1 mg dry matter substrate at different levels of inclusion: Without lysozyme, 2,000, 4,000, and 8,000 U lysozyme. Results revealed that, lysozyme addition had a significant effect on pH after 24 h of incubation, with the highest pH (p<0.01) observed in 8,000 U lysozyme, followed by the 4,000 U, 2,000 U, and without lysozyme. The highest amounts of acetic acid, propionic acid (p<0.01) and total volatile fatty acid (TVFA) (p<0.05) were found in 8,000 U after 24 h of incubation. The CH₄ concentration was the lowest in the 8,000 U and the highest in the without lysozyme addition after 24 h of incubation. There was no significant differences in general bacteria, methanogen, or protozoan DNA copy number. So far, addition of lysozyme increased the acetate, propionate, TVFA, and decreased CH₄ concentration. These results suggest that lysozyme supplementation may improve in vitro rumen fermentation and reduce CH₄ emission.