Effects of storage time on nutritive qualities, volatile components, and microbial community of native grass hay

Microbial activity in stored native grass hay may induce quality deterioration and alter flavor profiles, resulting in significant economic losses and forage safety risks. This study elucidated the association between microbial communities, nutritive qualities, and volatile components during native grass hay storage. High-throughput sequencing was conducted for determining the microbial composition of stored native grass hay. Headspace solid-phase microextraction-gas chromatography-mass spectrometry was performed for identifying volatile compounds in native grass hay. This study also assessed the correlation of volatile compounds with the hay microbiome. According to the obtained results, the water-soluble carbohydrate and crude protein content of native grass hay significantly decreased by 14.37% and 25.24%, respectively, after 360 days of storage (P < 0.01). From the 112 volatile compounds identified in native grass hay, hydrocarbons and alcohols were the major contributors to the volatile profile characteristics of native grass hay during storage, while ketones, heterocyclic compounds, and aromatic compounds were the minor constituents. Forty-nine potential spoilage markers were screened based on OPLS-DA and VIP values. The dominant fungi at the phylum level were Ascomycota and Basidiomycota. Alternaria and Kabatiella were the main fungal genera during the storage of native hay. Correlation analysis showed that 3 key volatile compounds (eucalyptol, geranyl acetone, and dihydroactinidiolide) exhibited a high association with quality loss and Aspergillus of native grass hay. The present findings could improve our knowledge about how storage affects microbial communities and volatile components in native grass hay.