Effects of additives and storage time on chemical composition and microbial population of native grass pellet

The objective of this study was to investigate the effects of additives and storage time on the chemical composition and microbial population of native grass pellets. Scutellaria baicalensis and propionic acid were added to native grass, with a mass fraction of 1%, to make pellets. Samples were taken at 0, 30, 60, 90, 120, and 150 days of storage to determine the chemical composition and the number of microorganisms. The results showed that storage time had significant effects on dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) contents of native grass pellets (P < 0.05), and at the later stage of storage, the contents of NDF and ADF in native grass pellets decreased significantly (P < 0.05); but storage time had no significant effects on their crude protein (CP) and organic matter (OM) contents; the DM content of native grass pellets showed an increasing trend during storage, and tended to be stable at 120 d. At a later stage of storage, the content of NDF and ADF in native grass pellets decreased significantly (P < 0.05). Propionic acid significantly increased the contents of DM, NDF, and ADF in native grass pellets during storage (P < 0.05) and decreased the number of Escherichia coli and aerobic bacteria attached to the pellets ( P < 0.05). The addition of Scutellaria baicalensis significantly increased OM content (P < 0.05), decreased CP content (P < 0.05), and significantly inhibited the activities of yeast and aerobic bacteria on the surface of native grass pellets ( P < 0.05).