# Effect of wild yeast inoculation on the nutritive value, fermentation profile, and aerobic stability of rehydrated corn grain silage

## TL;DR

This study examines how adding wild yeast to rehydrated corn silage affects its nutritional value, fermentation, and stability, finding that high yeast levels may reduce digestibility for dairy cows.

## Contribution

The study identifies that high wild yeast populations in rehydrated corn silage can reduce in vitro dry matter degradability, potentially impacting dairy cow performance.

## Key findings

- High wild yeast populations reduced 7-hour in vitro dry matter degradability.
- Ethanol concentration increased linearly with higher wild yeast inoculation.
- Total and lactic acid concentrations were higher in silage with high yeast counts.

## Abstract

Summary: In the current study, wild yeast was obtained from high-moisture corn that was exposed to an aerobic environment for 10 days to promote yeast growth. Dry ground corn was rehydrated targeting 70% dry matter (DM) and inoculated with wild yeast to achieve final yeast concentrations of 0, 5.3, 6.3, and 7.3 log colony forming units/mL. Silos were placed in vacuum pouches and stored for 30 or 90 days. Increasing wild yeast inoculation did not largely influence silage nutritive value. However, high wild yeast population reduced 7-hour in vitro DM degradability, which in turn could potentially affect performance of dairy cows.

Summary: In the current study, wild yeast was obtained from high-moisture corn that was exposed to an aerobic environment for 10 days to promote yeast growth. Dry ground corn was rehydrated targeting 70% dry matter (DM) and inoculated with wild yeast to achieve final yeast concentrations of 0, 5.3, 6.3, and 7.3 log colony forming units/mL. Silos were placed in vacuum pouches and stored for 30 or 90 days. Increasing wild yeast inoculation did not largely influence silage nutritive value. However, high wild yeast population reduced 7-hour in vitro DM degradability, which in turn could potentially affect performance of dairy cows.

•Wild yeast inoculation did not largely influence silage nutritive value.•Silage had greater yeast counts and a less pronounced fermentation.•Ethanol concentration linearly increased with increasing wild yeast inoculation.•High wild yeast populations reduced 7-hour in vitro DM degradability.

Wild yeast inoculation did not largely influence silage nutritive value.

Silage had greater yeast counts and a less pronounced fermentation.

Ethanol concentration linearly increased with increasing wild yeast inoculation.

High wild yeast populations reduced 7-hour in vitro DM degradability.

Feeding spoiled silage with high yeast activity is commonly related to impaired lactation performance by dairy cows. However, rehydrated corn grain silage (RCGS) may be more prone to yeast proliferation and be greatly affected by high yeast populations. This experiment assessed the effects of increasing wild yeast counts on the nutrient composition, fermentation profile, and aerobic stability of RCGS at different storage lengths. Wild yeast was obtained after exposing high-moisture corn to an aerobic environment for 10 d. The experiment consisted of 4 treatments (theoretical concentration of 0 [only distilled water; CON], 5.3 [low yeast; LY], 6.3 [medium yeast; MY], and 7.3 [high yeast; HY] log cfu/g of RCGS) for either 30 or 90 d of storage in quadruplicate (used as blocking factor), for a total of 32 laboratory silos. Minimal changes in nutrient composition and aerobic stability were detected regardless of treatment and storage length. At 30 d, acetic acid and ethanol concentrations showed a positive linear relationship with increasing wild yeast count. Greater yeast count was observed in silage inoculated with wild yeast compared with CON, but no differences were detected among inoculated silage. The 7-h in vitro DM degradability linearly decreased with increasing wild yeast counts. At 90 d, total acid concentration was greater for HY compared with other treatments, with a positive quadratic relationship when increasing wild yeast count. Similarly, lactic acid concentration was greater for HY compared with other treatments, with a positive linear relationship when increasing wild yeast count. In addition, HY had greater ethanol concentration compared with other treatments, with a positive linear relationship when increasing wild yeast count. The 7-h in vitro DM degradability was quadratically related to wild yeast population. Overall, this study provides additional information regarding the nutrient composition, fermentation profile, and aerobic stability of RCGS with wild yeast inoculation. Moreover, high wild yeast populations can reduce in vitro DM degradability, which could potentially affect performance of dairy cows. Further research is warranted to identify wild yeast populations as their presence is dependent on their species and metabolism.