Effects of small-scale silo types and additives on silage fermentation and bacterial community of high moisture alfalfa on the Qinghai-Tibetan Plateau

Abstract

Alfalfa is cultivated throughout the world, but its preservation remains challenging to small farms in cold climates. This study aimed to investigate the effects of small-scale silo types and additives on the silage quality of high moisture alfalfa on the Qinghai-Tibetan Plateau. Alfalfa with moisture of about 80% was ensiled in small farm bucket silos (FBS) or wrapped bale silos (WBS) at ambient temperature (5–15 °C) for 180 days. At ensiling, forage was treated without any additive (CK) or with a chemical additive (SB; a mixture of sodium benzoate, potassium sorbate, and sodium nitrite) or a lactic acid bacteria (LAB) inoculant (PBB; a mixture of Lactiplantibacillus plantarum, Bifidobacterium brevis and Pediococcus pentosaceus). Among the CK silages, higher (P < 0.05) acetic acid levels, bacterial diversity indices and relative abundance of L. plantarum were found in WBS vs FBS. Overall, silage treated with SB had the highest crude protein (CP) content, the lowest amylase-treated neutral detergent fiber (aNDF) and acid detergent fiber (ADF) contents and dry matter (DM) loss. Compared with CK, treatments with SB and PBB increased (P < 0.05) lactic acid content and decreased (P < 0.05) final pH value and butyric acid content of silage. In addition, treatment with PBB reduced (P < 0.05) the relative abundance of Lactilactobacillus sakei and increased (P < 0.05) the similarity of silage samples from different silos. There was negligible difference in fermentation quality of silage occurred between the types of silos. However, small WBS tended to increase the relative abundance of L. plantarum for more desirable silage fermentation. Application of additives at ensiling enhanced the preservation of silage nutrients with low DM loss. Based on the above results, small WBS were recommended for producing high-quality alfalfa silage on the Qinghai-Tibetan Plateau.