Abstract: To determine the optimal drying duration for forage oat （Avena sativa L.） hay preparation and mitigate fungal contamination risks， this study monitored microbial counts and the succession of fungal communities on oats and the attached topsoil during the drying process （days 1-5）. The results showed that with prolonged drying time， the counts of molds， yeasts， coliforms， and aerobic bacteria in both oats and topsoil generally exhibited a logarithmic growth trend. Specifically， aerobic bacteria counts remained at their lowest levels on days 1-2， while mold counts peaked on day 3. Notably， from days 2 to 5， the counts of molds and aerobic bacteria significantly exceeded the limits specified in the Hygienic Standard for Feeds （GB 13078-2017）. Regarding community structure， Ascomycota （72.24%） and Basidiomycota （21.10%） were identified as the dominant phyla. The dominant genera on the oat surface exhibited a distinct succession pattern： the relative abundances of Bulleromyces （19.22%） and Sarocladium （16.12%） decreased with prolonged drying， whereas those of Microdochium （15.14%） and Cryptococcus （11.07%） significantly increased. Correlation network analysis indicated that the fungal community network underwent a topological shift from a simple， sparse structure in topsoil to a complex， dense structure on oat plants. Furthermore， correlation analysis revealed a succession path of potential pathogens： the community dominated by potential toxin-producing or endophytic pathogenic taxa （represented by Sarocladium and Acremonium） in the topsoil gradually evolved into a community dominated by soil-borne root rot pathogens （represented by Plectosphaerella and Idriella） on the plants. In conclusion， to inhibit pathogen colonization and ensure the hygienic quality of hay， it is recommended to control the drying duration within 1-2 days in production practice.

Key words: Feed oats, Hay modulation, Fungi, Fungal community

摘要： 为探究饲用燕麦干草调制的最佳晾晒时长以降低真菌污染风险，本研究监测了晾晒过程（1~5 d）中燕麦及其附着表土的微生物数量与真菌群落演变。结果显示：随着晾晒时间的延长，燕麦与表土中的霉菌、酵母菌、大肠菌群及好氧细菌数量总体呈对数增长趋势。其中，好氧细菌数量在第1~2 d维持在最低水平，霉菌数量于第3 d达到峰值；值得注意的是，第2~5 d的霉菌及好氧细菌数量已显著超过GB 13078-2017饲料卫生标准。在群落结构上，子囊菌门（72.24%）和担子菌门（21.10%）为绝对优势菌门。燕麦表面的优势属表现出明显的演替规律：布勒掷孢酵母属（Bulleromyces，19.22%）和帚枝霉属（Sarocladium，16.12%）丰度随晾晒时间延长而降低，而微座孢属（Microdochium，15.14%）及隐球菌属（Cryptococcus，11.07%）丰度则显著升高。相关性网络分析表明，从表土到燕麦植株，真菌群落网络经历了由简单稀疏向复杂紧密的结构转变，且相关性分析进一步揭示了表土中以Sarocladium和顶孢霉属（Acremonium）为代表的潜在内生致病类群，逐渐演变为植物体上以褶球壳属（Plectosphaerella）和伊德里霉属（Idriella）为主导的土传根腐病原菌群落的潜在致病菌群的演替路径。综上所述，为阻断病原菌定殖并保障干草卫生品质，建议在生产实践中将晾晒时间控制在1~2天以内。

关键词: 饲用燕麦, 干草调制, 霉菌, 真菌群落