Akademik Veri Yönetim Sistemi
Ankara Universitesi Veteriner Fakultesi Dergisi, cilt.73, sa.2, ss.145-153, 2026 (SCI-Expanded, Scopus, TRDizin)
A B S T R A C T The aim of the present study was to investigate the in vitro effects of two lysozyme doses (10 and 50 FIP U/mL) on rumen fermentation and microbial populations using the artificial rumen system Rusitec with an 80:20 concentrate-to-forage diet. The ruminal pH, the total number of protozoa, total and individual volatile fatty acid (VFA) production, and methane (CH4) release were not significantly affected by the tested quantities of lysozyme. However, the ammonia nitrogen (NH3-N) concentration was significantly increased by supplementation with Lysozyme-50 (P < 0.05). The dry matter digestibility (DMD) was significantly higher in Lysozyme-50 than in Lysozyme-10 (P < 0.05). The total bacterial count decreased linearly in response to the addition of Lysozyme-50 (P < 0.05). Furthermore, in the presence of Lysozyme-50, the abundance of Butyrivibrio fibrisolvens decreased in both linear and quadratic manners (P < 0.05), and the abundance of Fibrobacter succinogenes decreased in a linear manner (P < 0.05). A linear decline tendency in the cell numbers of Ruminococcus albus (P = 0.092) and Megasphaera elsdenii (P = 0.085) was observed with Lysozyme-50 treatment. These findings suggest that while core fermentation parameters such as VFA production and digestibility remained stable, the elevated ammonia nitrogen concentration may reflect reduced nitrogen utilization efficiency, particularly at high doses. Additionally, since lysozyme has limited selectivity for certain rumen bacteria within the Rusitec system, lysozyme may influence rumen microbes differently from conventional antibiotics, warranting further in vitro and in vivo studies across diverse diets and dose ranges.