This study aimed to explore the diversity and functions of rumen mycobiota in 14‑ (PLf) and 15‑rib (DLf) Jiani yaks using ITS sequencing. A total of 1,079,105 and 1,086,799 filtered sequences were obtained for the PLf and DLf groups, respectively, with 491 ASVs common to both. No significant difference regarding the α‑diversity of mycobiota within the two groups was observed. While β‑diversity analysis indicated that the abundance of fifteen (15) genera in the PLf group and two (2) genera in the DLf group was found to be significantly different (p <
0.05). 16S rRNA sequencing results indicated that at the phylum level, in 14 ribs yaks Ascomycota, Basidiomycota, and Olpidiomycota, while in 15 rib yaks, Neocallimastigomycota, Mortierellomycota, and Rozellomycota were found to be significantly different (