Comparison of the Effects of Microbial Inoculants on Fermentation Quality and Microbiota in Napier Grass (Pennisetum purpureum) and Corn (Zea mays L.) Silage

Abstract

Forage preservation for livestock feeding is usually done by drying the plant material and storing it as hay or ensiling it into silage. During the ensiling process, the pH in the system is lowered by the activities of lactic acid-producing bacteria (LAB), inhibiting the growth of spoilage microorganisms and maintaining the quality of the ensiled product. To improve this process, inoculation of LAB could be used as starter cultures to shorten the ensiling time and control the fermentation process. Here, we compared fermentation quality and bacterial dynamics in two plant materials, whole-plant corn (Zea mays L.) and Napier grass (Pennisetum purpureum), with and without starter inoculation. The efficacy of Lactobacillus plantarum, L. brevis, and Pediococcus pentosaceus as starter cultures were also compared in the ensiling system. In whole-plant corn, pH decreased significantly, while lactic acid content increased significantly on Day 3 in both the non-inoculated and LAB-inoculated groups. Prior to ensiling, the predominant LAB bacteria were Weissella, Enterococcus, and Lactococcus, which shifted to Lactobacillus during ensiling of whole-plant corn in both the non-inoculated and LAB inoculated groups. Interestingly, the epiphytic LAB associated with Napier grass were much lower than those of whole-plant corn before ensiling. Consequently, the fermentation quality of Napier grass was improved by the addition of LAB inoculants, especially L. plantarum and a combination of all three selected LAB strains showed better fermentation quality than the non-inoculated control. Therefore, the different abundance and diversity of epiphytic LAB in plant raw materials could be one of the most important factors determining whether LAB starter cultures would be necessary for silage fermentation.

Ensiling hybrid Pennisetum with lactic acid bacteria or organic acids improved the fermentation quality and bacterial community

“…The LP treatment had the lowest pH and highest lactic acid content of all treatments. It is likely that lactic acid has a lower pH than other organic acids and plays a vital role during fermentation ( Jaipolsaen et al, 2021 ). In this study, the concentration of lactic acid at 30 days was greater ( p < 0.05) than at 60 days of ensiling in all treatments, except for the PA treatment.…”

A meta-analysis to observe silage microbiome differentiated by the use of inoculant and type of raw material

“…. Enterobacter is known to cause silage spoilage (Jaipolsaen et al, 2022). As shown in Tables 5, 7, the addition of LAB is effective in improving silage preservation by increasing the abundance of Lactobacillus, L. buchneri, and L. plantarum.…”

“…Inoculation of low-temperature tolerant LAB at ensiling could stimulate favorable fermentation and reconstruct the bacterial community for better preservation of highly moist oat silage nutrients (Chen et al, 2020). Jaipolsaen et al (2022) reported the importance of identifying suitable starter cultures, understanding the natural flora of epiphytic LAB on plants, and applying them together to optimize cost-effective silage production. Among the most used starter cultures of LAB is Lactobacillus plantarum (Keshri et al, 2018;Mu et al, 2020).…”

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage

“…Applying LAB inoculant (T3) on maize silage during ensiling favoured the dominancy of phylum Bacteroidetes followed by phyla Firmicutes and Proteobacteria. On the contrary, Jaipolsaen et al [48] and Dong et al [49] reported Firmicutes bacteria as the dominant phylum on maize silage treated with LAB inoculant during ensiling. However, other studies reported Proteobacteria as the dominant phylum on silage produced from different forages while treated with LAB inoculant during ensiling [20,27,41].…”