Effects of Aspergillus Oryzae Culture and 2-Hydroxy-4-(Methylthio)-Butanoic Acid on In vitro Rumen Fermentation and...

Area of Science:

• Ruminant nutrition and microbiology
• In vitro fermentation studies
• Feed additive efficacy

Background:

• Rumen fermentation is crucial for nutrient utilization in ruminants.
• Aspergillus oryzae culture (AOC) and 2-hydroxy-4-(methylthio)-butanoic acid (HMB) are potential feed additives.
• The impact of these additives can vary with different forage types.

Purpose of the Study:

• To evaluate the effects of AOC and HMB on rumen fermentation parameters.
• To assess the influence of AOC and HMB on rumen microbial populations.
• To investigate these effects across two distinct roughage sources: Chinese wild rye (CWR) and corn silage (CS).

Main Methods:

• An in vitro experiment utilizing a 2x3 factorial arrangement.
• Treatments included two roughage sources (CWR vs. CS) and combinations of HMB (0 or 15 mg) and AOC (0, 3, or 6 mg).
• Measurements included gas production (GP), microbial protein (MCP), volatile fatty acids (VFA), ammonia-N, and microbial populations (protozoa, fungi, specific bacteria).

Main Results:

• Both HMB and AOC increased GP, MCP, and total VFA (p<0.01) for both roughages.
• Effects on ammonia-N varied with substrate; individual VFA proportions were mainly unaffected by HMB/AOC in CWR but altered in CS.
• HMB and AOC generally increased beneficial bacterial populations (F. succinogenes, R. albus) and influenced protozoa and fungi populations differently depending on the substrate.

Conclusions:

• Addition of HMB and AOC can enhance rumen fermentation and microbial protein synthesis in vitro.
• The efficacy of these additives is influenced by the type of roughage used.
• These findings suggest that HMB and AOC can modulate rumen microbial ecosystems, potentially improving forage utilization.