In vitro evaluation of Saccharomyces cerevisiae cell wall fermentability using a dog model

Area of Science:

• Animal Nutrition and Feed Science
• Microbiology
• Biochemistry

Background:

• Saccharomyces cerevisiae cell walls are potential feed ingredients.
• Understanding their fermentation characteristics is crucial for optimizing animal nutrition.
• Different production processes may alter yeast cell wall composition and fermentability.

Purpose of the Study:

• To evaluate the in vitro fermentation of Saccharomyces cerevisiae cell wall substrates.
• To compare the effects of different production processes (alcoholic, bakers, brewers) and carbohydrate concentrations on fermentation.
• To assess the impact of yeast cell wall composition on organic matter degradability, gas production, and short-chain fatty acids.

Main Methods:

• In vitro gas production technique using dog feces as inoculum.
• Incubation of six Saccharomyces cerevisiae cell wall samples from different production processes and carbohydrate concentrations for 72 hours.
• Measurement of gas production, organic matter degradability (OMD), pH, short-chain fatty acids (SCFA), and ammonia (NH3).

Main Results:

• All substrates exhibited high OMD (>92%) and moderate fermentability.
• S. cerevisiae_BR showed the highest OMD, gas, and SCFA production with a fast fermentation rate.
• S. cerevisiae_BA demonstrated lower degradability and fermentability, attributed to higher ether extract content.
• S. cerevisiae_A presented high degradability but lower gas and SCFA production, potentially due to high protein content.

Conclusions:

• The production process significantly influences the chemical composition and in vitro fermentation of Saccharomyces cerevisiae cell walls.
• Brewers yeast cell walls (S. cerevisiae_BR) are highly degradable and fermentable, making them a promising feed ingredient.
• Bakers yeast cell walls (S. cerevisiae_BA) require further investigation due to lower fermentability, possibly linked to ether extract content.