Screening and identification of low-temperature resistant lactic acid bacteria and its effect on fermentation quality of oat silage

We aimed to explore the effects of lactic acid bacteria with good growth rate and resistant to low temperature conditions on the fermentation quality of oat silage in Baihe Ranch of Ruoergai County. The low temperature-resistant strains were screened using the restrictive culture method and identified using 16S rRNA sequence analysis. The results showed that: 1) Lactobacillus strain YZ3 had the best growth rate and acid production performance at the low temperature of 4 ℃ (pH could reach 5.38), and could tolerate low pH (4.0) and high salt concentration (6.5% NaCl). 2) The strain YZ3 was identified as L. paracasei by physiological and biochemical tests, colony morphology, Gram staining, and 16S rRNA sequence analysis. 3) Under a low temperature environment, the lactic acid content of oat silage treated with YZ3 increased to 63.7 mg·g⁻¹, which was significantly higher than that of the control (P < 0.05), and the pH of silage decreased to 4.1, which was significantly lower than that of the control (P < 0.01). In summary, the addition of lactic acid bacteria YZ3 improved the silage fermentation quality of oats and can be used as a low-temperature silage strain in the alpine region of northwest Sichuan.