The rumen is a microbial-rich ecosystem in which rumen fungi play an important role in the feed digestion of ruminants. The composition of rumen fungi in free-range ruminants such as gayals, yaks, Tibetan yellow cattle, and the domesticated Yunnan yellow cattle was investigated by sequencing an internal transcribed spacer region 1 (ITS1) using Illumina MiSeq. A total of 285 092 optimized sequences and 904 operational taxonomic units (OTUs) were obtained from the four cattle breeds. The rumen fungi abundance and Chao and Simpson indexes were all higher in free-range ruminants than in domesticated ruminants. Three fungal phyla were identified by sequence comparison: Neocallimastigomycota, Basidiomycota, and Ascomycota. Basidiomycota and Ascomycota have very low abundance in the rumen of four breeds cattle but anaerobic fungi (AF) Neocallimastigomycota occurred in a high abundance. In Neocallimastigomycota, the dominant genera were Piromyces, Anaeromyces, Cyllamyces, Neocallimastix, and Orpionmyces in four cattle breeds. The composition of the major genera of Neocallimastigaceae varied greatly among the four cattle breeds. The unclassified genera were unequally distributed in gayals, yaks, Tibetan and Yunnan yellow cattle, accounting for 90.63%, 98.52%, 97.79%, and 27.01% respectively. It appears that free-range ruminants have more unknown rumen fungi than domesticated ruminants and the cattle breeds and animal diets had an impact on the diversity of rumen fungi.

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An infrared perfect absorber structure is designed based on GaAs/Au/SiO2 metamaterial with numerical simulation, in which gold split ring resonators (SRR) embedded in the GaAs layer. The absorption exceeds 99% at 1360 nm under the plane wave excitation with its polarization perpendicular to the opening direction of the SRR. When the polarization of the plane wave is parallel to the opening direction, the absorption exceeds 97% and 56% at 970 and 2070 nm, respectively, which realize dual-band absorption. The absorption peaks are effectively modulated by controlling surface current density distribution and resonant electromagnetic response. In addition, the resonant wavelengths are further manipulated by optimizing the resonant ring structural parameters, which achieve ultrawide-band absorption ranging from near-infrared to mid-infrared region. The absorber remains absorption peaks above 96% under wide-angle plane wave incidence, and the resonant peak positions are independent of the incident angle. This work exhibits the promise of GaAs-based metamaterial in practical applications in energy harvesting and night vision imaging.