Lactic acid bacteria (LAB) have been proposed for the control of undesirable fermentation and, subsequently, aerobic deterioration due to their ability to produce antimicrobial metabolites in silage mass. To investigate the effect of specific LAB on the silage fermentation characteristics and bacterial community composition of oat in cold regions, silages were treated without (control) or with three LAB strains (LB, Lentilactobacillus buchneri; nLP, low temperature tolerant Lactiplantibacillus plantarum; pLP, phenyllactic acid-producing Lactiplantibacillus plantarum), and then stored at ambient temperature (−2.63 ± 5.47–14.29 ± 5.48 °C) for 30, 60, and 90 days. Compared with control, inoculation of LAB decreased the final pH value, butyric acid content, ammonia-N of total N and dry matter loss of silage. Treatments with nLP and pLP increased (p < 0.05) lactic acid content, whereas LB increased (p < 0.05) acetic acid content of silage. Lactiplantibacillus and Leuconostoc dominated in the silages with relative abundance of 68.29–96.63%. A prolonged storage period enhanced the growth of Leuconostoc in pLP-treated silage. In addition, pLP increased (p < 0.05) the aerobic stability of silage as compared with nLP. In conclusion, inoculation of LAB improved silage fermentation and/or delayed aerobic deterioration by shifting bacterial community composition during ensiling. Phenyllactic acid-producing Lactiplantibacillusplantarum as an inoculant exhibited potential for high quality silage production.

To effectively use local grass resources to cover the winter feed shortage on the Qinghai-Tibetan Plateau, the silage fermentation and in vitro digestibility of perennial oat (Helictotrichonvirescens Henr.) were investigated. Perennial oat was harvested at the heading/flowering stage, wilted under sunny conditions, chopped, vacuumed in small bag silos, and stored at ambient temperatures (5–15 °C) for 60 days. The silages were treated without (CK) or with local lactic acid bacteria (LAB) inoculant (IN1), commercial LAB inoculant (IN2), and sodium benzoate (BL). Control silages of perennial oat at early heading stage showed higher (p < 0.05) lactate and acetate contents and lower (p < 0.05) final pH, butyrate, and ammonia-N contents than those at the flowering stage. High levels of dry matter recovery (DMR) and crude protein (CP) were observed in IN1- and BL-treated silages, with high in vitro gas production and dry matter digestibility. Compared to CK, additives increased (p < 0.05) aerobic stability by inhibiting yeasts, aerobic bacteria, and coliform bacteria during ensiling. In particular, the local LAB inoculant increased (p < 0.05) concentrations of lactate, acetate and propionate, and decreased concentrations of butyrate and ammonia-N in silages. This study confirmed that local LAB inoculant could improve the silage quality of perennial oat, and this could be a potential winter feed for animals such as yaks on the Qinghai Tibetan Plateau.

This study aimed to investigate the effect of oat silage treated with a low-temperature-tolerant lactic acid bacteria (LAB) inoculant on milk yield and the quality of lactating yaks. Oat silages were prepared in big round bales, treated without (control) or with a low-temperature-tolerant LAB inoculant (a mixture of Lactobacillus plantarum BP18, Pediococcus pentosaceus HS1 and Lactobacillus buchneri LP22; the application rate of 10⁵ cfu/g on a fresh matter basis). Eighteen lactating yaks were divided into nine pairs with a similar milk yield. Each pair of yaks was randomly allocated to the control or LAB-inoculated silage treatment. The inoculated silage increased the dry matter intake and the total volatile fatty acid (mainly acetate, propionate and butyrate) in rumen fluid compared with the control. The inoculated silage also enhanced the yield of yak milk with high contents of total N, fat and lactose. In addition, high levels of essential amino acids (Thr, Leu and Phe), polyunsaturated fatty acids and low saturated fatty acids were observed in milk when lactating yaks were fed with the inoculated silage. Therefore, inoculation with a low-temperature-tolerant LAB during ensiling could promote the milk yield of lactating yaks by enhancing dry matter intake and ruminal fermentation.

Determining the effects of fermentation duration on the microbial ecosystem, potential pathogenic risks, and metabolite generation during the fermentation of distilled grains is essential for safeguarding the safety and enhancing the nutritional profile of animal feed. This study investigates the effect of varying fermentation times (9, 30, and 60 days) on microbial diversity, pathogenic risk, and metabolite profiles in distiller grains using 16S rDNA sequencing and LC–MS-based metabolomics. The results showed that early fermentation (9–30 days) enhanced the abundance of beneficial bacteria, such as Lactobacillus reuteri and Lactobacillus pontis (p < 0.05), while pathogenic bacteria, like Serratia marcescens and Citrobacter freundii, were significantly reduced (p < 0.05). Metabolomic analysis revealed an increase in unsaturated fatty acids and the degradation of biogenic amines during early fermentation. However, prolonged fermentation (60 days) led to a resurgence of pathogenic bacteria and reduced the synthesis of essential metabolites. These findings suggest that fermentation duration must be optimized to balance microbial safety and nutrient quality, with 30 days being the optimal period to reduce pathogenic risks and enhance feed quality.

The effects of additives on perennial ryegrass (Lolium perenne L., LP) silage’s metabolites, microbial diversity and microbial metabolic pathways have been less studied in karst areas. This experiment sought to ascertain the impact of formic acid (F) and lactic acid bacteria (LAB) preparations introduced in karst locations on the fermentation products of LP silage, the makeup of bacterial population and the projected functional characteristics. The experiment proceeded as follows: (1) for the CK treatment, 5 mL kg⁻¹ fresh weight (FW) of distilled water was added; (2) for the F treatment (88%), 5 mL kg⁻¹ FW of formic acid was added; (3) for the L treatment, Lactobacillus plantarum was mixed with Lactobacillus brucei at 2 × 10⁷ cfu/g FW. For 7, 15 and 45 days, the silage samples were kept at room temperature (20–25 °C). On day 45, the amount of lactic acid (LA) in the silage samples was substantially higher (p < 0.05) in the F (6.56% DM) and L (6.94% DM) treatments than in the CK treatment (4.47% DM), and the F treatment also had significantly lower pH and NH₃-N contents than the CK and L treatments. The concentration of lactic acid (LA) was significantly higher (p < 0.05) in the F (6.56% DM) and L (6.94% DM) treatments than in the CK treatment (4.47% DM). On day 45, the dominant genera for the F and L treatments were Lactiplantibacillus (28.78% and 20.34%), Lentilactobacillus (18.85% and 12.67%) and Secundilacillus (5.01% and 13.25%), while Hafnia-Obesumbacterium (16.94%) had a higher abundance in the CK treatment. The F and L treatments promoted microbial metabolic pathways such as “metabolism”, “genetic information processing” and “organismal systems”. They reduced other microbial metabolic pathways such as “membrane transport”, “signal transduction” and “ABC transport”. In summary, F and L can enhance the quality of LP silage in karst areas by improving the structure and function of microbial communities.