July 17, 2019

Interpretive Summary: Saccharomyces cerevisiae and Lactobacillus buchneri on microbial communities during ensiling

Interpretive Summary: Impact of Saccharomyces cerevisiae and Lactobacillus buchneri on microbial communities during ensiling and aerobic spoilage of corn silage.

By: Anne Wallace

Ensiling—fermentation facilitated by lactic acid producing bacteria (LAB) naturally present in forage or inoculated—preserves nutrients, increases digestibility, and prevents spoilage of high-moisture forage. Depending on the fermentative byproducts produced by LAB, they may be classified as first-, second-, or third-generation inoculants.

Saccharomyces cerevisiae is a direct-fed microbial (DFM) probiotic yeast with potential health benefits in ruminants. In this paper published in the March 2019 Journal of Animal Science, researchers suggest S. cerevisiae as a fourth-generation inoculant to deliver this DFM yeast. The research objective was to determine the effectivity of S. cerevisiae and LAB Lactobacillus buchneri on the quality of corn silage (i.e. fermentation characteristics, nutritional quality, microbial community and aerobic stability).

In this study, corn crop was inoculated with S. cerevisiae NRRL Y-50736 and/or L. buchneri NRRL B-50733 and ensiled for 118 days. Inoculation occurred as follows: (a) control—not inoculated; inoculation with (b) S. cerevisiae 104 cfu/g without L. buchneri (S4); (c) S. cerevisiae 105 cfu/g without L. buchneri (S5); (d) S. cerevisiae 104 cfu/g + L. buchneri 105 cfu/g (S4L5), and (e) S. cerevisiae 105 cfu/g + L. buchneri 104 cfu/g (S5L4).

Ensiling was successful for all treatments. Aerobic stability, nutrient profile and fermentation byproducts were unaffected by S. cerevisiae compared to control, with exception of some increase in acetic acid in inoculated silage, and acid detergent insoluble nitrogen (ADIN) in S4L5, with negligible impact on the ensiling process. After aerobic exposure, a significant increase in the concentration of S. cerevisiae occurred in the inoculated silage. Bacterial but not fungal microbial populations were also altered in the S. cerevisiae and L. buchneri combination.

The results of this study suggest that S. cerevisiae does not detrimentally affect the ensiling process of corn crop with L. buchneri. Additionally, aerobic exposure after ensiling increased S. cerevisiae concentration. Dr. McAllister, corresponding author, emphasizes: “This is the first step towards the development of a 4th generation silage inoculant that could offer direct benefits to the ruminant host. As the pressure to eliminate the use of in-feed antimicrobials continues to grow, we need to explore alternative approaches to improving the efficiency and health of cattle.  The direct administration of probiotics in silage may be one way to accomplish this.” More in-depth studies on the interactions of S. cerevisiae with other LAB and the potential health benefits silage inoculated with S. cerevisiae may confer on ruminants is warranted.  

To view the article, visit the Journal of Animal Science.