To explore the seasonal variation patterns of the skin microecology of Altay sheep under transhumant grazing conditions, skin swabs were collected from 60 free-grazing Altay sheep at seasonal transition nodes in the Altay region. Metagenomic sequencing combined with untargeted metabolomics was used to characterize their bacterial community structure, functional pathways, and metabolite profiles. The results showed that the skin microecology of Altay sheep presented obvious seasonal variation patterns. In spring, 35 of the 39 highly abundant bacteria were environmentally derived, five proliferation-related pathways were significantly enriched, and the levels of five metabolites associated with microbial community regulation and skin barrier defense were elevated. In summer, the abundance of three skin symbiotic bacteria increased, the activities of eight pathways mainly related to biofilm formation were significantly enhanced, and the contents of five metabolites primarily associated with membrane lipid homeostasis and selective bacteriostasis increased. In autumn, the abundances of nine radiation-resistant and cold-tolerant strains increased, together with the elevated abundance of two opportunistic pathogens; five repair-related pathways were active, and the levels of four anti-inflammatory and repair-associated metabolites were synchronously increased. In winter, the abundance of two cold-tolerant strains increased, the activities of pathways related to nitrogen metabolism and energy synthesis were enhanced, and one lignan compound was identified as the key metabolite. These findings elucidate the seasonal dynamic patterns of the skin microecology of Altay sheep and provide a theoretical basis for research on the adaptive mechanisms and seasonal health management of Altay sheep and other sheep in alpine regions.

In this experiment, the rumen microbiota of healthy cows, cows with left-displaced abomasum (LDA), and cows after 7 days of LDA treatment (LDA_7) were compared to explore the correlation between LDA and the rumen microbiota and identify early warning markers for LDA. Compared with the healthy group and the LDA_7 group, the LDA group exhibited fewer Operational Taxonomic Units (LDA: 21,361; Healthy: 23,231; LDA_7: 23,956; p < 0.05). The results revealed significant differences in community structure between LDA-affected cows and healthy cows, as well as between treated and untreated LDA-affected cows. Specifically, the relative abundance of Bacteroidota significantly increased and the relative abundance of Firmicutes significantly decreased in LDA-affected cows (p < 0.05). At the genus level, the abundances of UCG_002, UCG_010, and Bacteroidales_BS11_gut_group significantly increased (p < 0.01), whereas those of Trichosporon, Chryseomicrobium, and [Ruminococcus]_gauvreauii_group significantly decreased in LDA-affected cows (p < 0.01). Functional prediction analysis indicated that amino acid biosynthesis and glycerol ester metabolism were significantly downregulated in LDA-affected cows (p < 0.01). After treatment, the abundance of key microbial taxa (UCG_002 and Lachnospira) and metabolic functions normalized to levels similar to healthy cows (p > 0.05). These findings suggest that changes in rumen microbiota richness and diversity could serve as early warning markers for LDA detection.

To prevent the spread of antibiotic resistance, bacteriophages have gradually become the most promising alternative to antibiotics for treating bacterial infectious diseases. In this study, using E. coli DC1 as the host strain, we isolated a bacteriophage named Escherichia coli phage XJA18 from farm sewage. We conducted morphological identification, host range determination, biological characteristic analysis, genomic feature analysis, and evaluation of in vitro and in vivo antibacterial effects. Electron microscopy revealed that phage XJA18 belongs to the class Caudoviricetes, with an icosahedral head and a non-contractile long tail. Whole-genome sequencing revealed that the phage has dsDNA with a length of 50,572 bp, with a GC content of 45.33%. The genome does not contain any antibiotic resistance genes or virulence genes, indicating good safety. XJA18 showed lytic activity against 24% of clinically isolated E. coli strains. The optimal multiplicity of infection (MOI) was 0.001, with a latent period of 10 min, a burst period of 30 min, and a burst size of 2.22 × 10² PFU/cell. It remained stable at 4–50 °C and pH 4–12. In vitro antibacterial results revealed that XJA18 had the most pronounced initial bacterial growth suppression at MOI = 0.001 during the first 4 h. In vivo experiments demonstrated that both prophylactic and therapeutic administration of XJA18 could protect against E. coli infection, significantly reducing inflammatory cytokine levels and bacterial loads in the livers and spleens of mice (p < 0.001), significantly increasing body weight (p < 0.05), and reducing histopathological damage to the colon, liver, and lungs. In summary, phage XJA18 can effectively inhibit E. coli and is safe and stable. These characteristics indicate that phage XJA18 has great potential as a novel biological agent to replace antibiotics for treating bacterial infectious diarrhea in calves.

Vermipsyllid parasitize the body surface of sheep, feeding on blood and transmitting diseases, causing severe economic losses to the livestock industry. An outbreak of sheep Vermipsyllid fleas in the mountain pastures of Xinjiang’s Altai region showed that several commonly used commercial anthelmintic drugs had poor therapeutic effects on the prevalent flea species. This study first conducted species identification of Vermipsyllid through morphological analysis of 200 female and 40 male specimens collected from the Altai region, followed by molecular biological identification of 6 randomly selected fleas (3 females and 3 males). Finally, pharmacodynamic experiments were performed to screen for highly effective anthelmintic drugs. Ninety Altai multiparous ewes infected with Vermipsyllid were divided into six groups (fifteen sheep per group): an untreated control group (Ctr), avermectin injection group (Group I), ivermectin injection group (Group II), moxidectin pour-on group (Group III), cypermethrin pour-on group (Group IV), and dichlorvos pour-on group (Group V), with a 14-day trial period. On Day 0, each group received a single treatment according to drug instructions and specified dosages. The number of fleas, flea population reduction rates, and cure rates were measured on Day 0, Day 3, Day 7, and Day 14 to screen for effective anthelmintic drugs. Results showed that unfed female and male fleas were grayish-brown. Engorged females reached 14.15 mm in size, appearing pale white or yellow, with their sterna maintaining the original size and shape despite abdominal distension. Female fleas had 20–21 segments on the labium, while males had 16–19 segments. The hind tibiae featured four notches, and each side of the tergite had 13 ± 1 cup-like indentations. Molecular biological identification indicated that the identified fleas belonged to D. ioffi (Vermipsyllidae, Dorcadia Ioff), showing 99.13% sequence similarity with D. ioffi from Xinjiang, China. In pharmacodynamic experiments, the number of D. ioffi in Groups IV and V decreased to zero on both Day 7 and Day 14, which was extremely significantly lower than other groups (p < 0.01). The flea population reduction rates in Groups IV and V reached 100% on both days. By Day 14, the cure rates of Groups I, II, and III were 0%, while those of Groups IV and V were 100%. Avermectin injection, ivermectin injection, and moxidectin pour-on showed poor anthelmintic effects, whereas cypermethrin and dichlorvos pour-on exhibited high anthelmintic activity against this flea species.