Abstract: The major constraint for forage storage is chemical composition and mycotoxin. To study the effects of baling density and stacking method on chemical composition and mycotoxin levels of native hay, a randomized split-plot experiment (2×3 factors) was carried out. Baling density as the primary factor and stacking method as the secondary factor was used. The primary factor was 160 and 120 kg·m^-3, the secondary factor was cross-stacking, vertical-stacking and transverse-stacking. Baling density was the main plot factor and sacking method was the subplot factor. For baling density, no significant differences were found for hay dry matter (DM), ash (Ash), neutral detergent fiber (NDF), aflatoxin B₁ (AFB₁), T-2 toxin (T-2) or ochratoxin A (OTA) (P>0.05). However, acid detergent fiber (ADF), crude protein (CP), deoxynivalenol (DON) and zearalenone (ZEN) did differ significantly with baling density (P<0.05). For stacking method, there were no significant differences in Ash, DM, ADF, NDF, CP, DON, AFB₁, T-2 and OTA (P>0.05). However, there was a significant difference between stacking methods for ZEN levels in the hay (P<0.05). In summary, baling density, and stacking method did significantly change hay chemical composition and mycotoxin levels. The optimal combination from this experiment in Xilinhot, was a baling density of 160 kg·m^-3 with cross-stacking of bales.

Key words: native grassland, hay, baling density, stacking ways, chemical composition, mycotoxin