Effects of Active Dry Yeast Supplementation in In Vitro and In Vivo Nutrient Digestibility, Rumen Fermentation, and...

Area of Science:

• Ruminant nutrition
• Animal microbiology
• Digestive physiology

Background:

• Active dry yeast (ADY) supplementation is explored to modulate rumen fermentation and improve animal performance.
• Understanding the specific effects of different ADY strains on nutrient digestibility and microbial populations is crucial for optimizing livestock diets.

Purpose of the Study:

• To evaluate the impact of two distinct active dry yeast strains, Vistacell (Vis) and Procreatin7 (Pro), on nutrient digestibility and rumen fermentation in lambs.
• To compare the efficacy of in vitro versus in vivo results for predicting ADY effects on rumen parameters and lamb growth.

Main Methods:

• In vitro batch cultures incubated ADY with rumen fluid and substrate to measure gas production, pH, volatile fatty acids (VFAs), and lactate.
• In vivo study with Hu lambs fed control or ADY-supplemented diets (Vis or Pro at two dosages) to assess growth, digestibility, rumen fermentation, and bacterial communities.
• Analysis included growth performance, nutrient digestibility, VFA profiles, and microbial community composition using 16S rRNA sequencing.

Main Results:

• Vistacell (Vis) increased propionate proportion and Succinivibrionaceae_UCG-001 abundance while decreasing n-butyrate proportion and Lachnospiraceae_ND3007 abundance in vivo.
• Vis demonstrated superior improvements in NDF digestibility and total VFA concentration compared to Pro.
• In vitro results showed Vis reduced lactate, but discrepancies existed between in vitro and in vivo findings regarding overall rumen fermentation modulation.

Conclusions:

• The effects of active dry yeast on rumen fermentation are strain-specific, with Vistacell being more beneficial for lamb growth and nutrient utilization.
• Vistacell promotes propionate fermentation and alters specific bacterial abundances, suggesting a targeted impact on rumen metabolism.
• Caution is advised when extrapolating in vitro fermentation results to in vivo animal responses due to observed differences.