Abstract:

The objective of this study was to improve the fermentation quality of Italian ryegrass silage and inhibit the loss of α-tocopherol and β-carotene during ensilage. Italian ryegrass was ensiled without additives （CK）， or with 0.4% propionic acid （PA）， Lactobacillus plantarum B11 （LP）， Bacillus circulans 12（BC）， or the combination of LP and BC （LP+BC）. At days 3， 7， 35， and 70 after ensiling， the Italian ryegrass silage fermentation quality， nutritional quality， α-tocopherol content， and β-carotene content were evaluated. It was found that additives significantly affected the silage fermentation quality （P<0.05）. The silage fermentation quality was the highest in the LP+BC treatment， followed by the LP treatment. In the later period of ensilage， compared with CK， all treatment groups showed lower pH values， all of which were below 4.0. Compared with CK， silages fermented with LP， BC， and LP+BC showed significantly increased lactic acid content and lactic acid/acetic acid ratio （P<0.05）. The addition of PA inhibited lactic acid fermentation in the early stage of ensilage and improved the fermentation quality in the later stage， but the effect of PA was weaker than those of the other three additives. During ensiling， the α-tocopherol content was significantly higher in silages fermented with PA than in those fermented with other additives or in CK （P<0.05）. After ensiling for 35 and 70 days， except for silages fermented with PA， those fermented with LP had the highest α-tocopherol contents （P<0.05）. After ensiling for 7 days， the β-carotene contents were higher in all the treatment groups than in CK （P<0.05）， and silage fermented with LP had the highest β-carotene content at days 7 and 35 after ensiling （P<0.05）. In conclusion， the addition of LP to Italian ryegrass silage resulted in good fermentation quality， reduced α-tocopherol losses， and increased the β-carotene content.

Key words: Italian ryegrass, additives, fermentation quality, α-tocopherol, β-carotene