AUTHOR=Hao Lihong , Jiang Fugui , Wang Yanping , Wang Huaizhong , Hu Hongmei , You Wei , Hu Xin , Cheng Haijian , Wang Cheng , Song Enliang 

TITLE=Formic acid enhances whole-plant mulberry silage fermentation by boosting lactic acid production and inhibiting harmful bacteria

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1399907

DOI=10.3389/fmicb.2024.1399907

ISSN=1664-302X

ABSTRACT=<p>Mulberry has also been regarded as a valuable source of forage for ruminants. This study was developed to investigate the impact of four additives and combinations thereof on fermentation quality and bacterial communities associated with whole-plant mulberry silage. Control fresh material (FM) was left untreated, while other groups were treated with glucose (G, 20 g/kg FM), a mixture of <italic>Lactobacillus plantarum</italic> and <italic>L. buchneri</italic> (L, 10<sup>6</sup> CFU/g FM), formic acid (A, 5 mL/kg FM), salts including sodium benzoate and potassium sorbate (S, 1.5 g/kg FM), a combination of G and L (GL), a combination of G and A (GA), or a combination of G and S (GS), followed by ensiling for 90 days. Dry matter content in the A, S, GA, and GS groups was elevated relative to the other groups (<italic>p</italic> &lt; 0.01). Relative to the C group, all additives and combinations thereof were associated with reductions in pH and NH<sub>3</sub>-N content (<italic>p</italic> &lt; 0.01). The A groups exhibited the lowest pH and NH<sub>3</sub>-N content at 4.23 and 3.27 g/kg DM, respectively (<italic>p</italic> &lt; 0.01), whereas the C groups demonstrated the highest values at 4.43 and 4.44 g/kg DM, respectively (<italic>p</italic> &lt; 0.01). The highest levels of lactic acid were observed in the GA and A groups (70.99 and 69.14 g/kg DM, respectively; <italic>p</italic> &lt; 0.01), followed by the GL, L, and GS groups (66.88, 64.17 and 63.68 g/kg DM, respectively), with all of these values being higher than those for the C group (53.27 g/kg DM; <italic>p</italic> &lt; 0.01). <italic>Lactobacillus</italic> were the predominant bacteria associated with each of these samples, but the overall composition of the bacterial community was significantly impacted by different additives. For example, <italic>Lactobacillus</italic> levels were higher in the G, A, and GA groups (<italic>p</italic> &lt; 0.01), while those of <italic>Weissella</italic> levels were raised in the L, GL, and GS groups (<italic>p</italic> &lt; 0.01), <italic>Pediococcus</italic> levels were higher in the A and GA groups (<italic>p</italic> &lt; 0.01), <italic>Enterococcus</italic> levels were higher in the G and S groups (<italic>p</italic> &lt; 0.01), and <italic>Lactococcus</italic> levels were raised in the S group (<italic>p</italic> &lt; 0.01). Relative to the C group, a reduction in the levels of undesirable <italic>Enterobacter</italic> was evident in all groups treated with additives (<italic>p</italic> &lt; 0.01), with the greatest reductions being evident in the A, S, GA, and GS groups. The additives utilized in this study can thus improve the quality of whole-plant mulberry silage to varying extents through the modification of the associated bacterial community, with A and GA addition achieving the most efficient reductions in pH together with increases in lactic acid content and the suppression of undesirable bacterial growth.</p>