Distribution and changes in urease (EC 3.5.1.5) activity in Rumen Simulation Technique (Rusitec)

Area of Science:

• Ruminant nutrition and biochemistry
• Microbial ecology
• Enzyme kinetics

Background:

• Urease activity is crucial for urea metabolism in the rumen.
• Understanding urease distribution is key to optimizing nitrogen utilization in ruminants.
• The Rumen Simulation Technique (Rusitec) provides a model for studying rumen fermentation.

Purpose of the Study:

• To investigate the distribution and dynamics of urease activity within the Rusitec system.
• To determine factors influencing urease activity, including urea infusion and feeding patterns.
• To compare urease distribution with other enzymes and microbial components.

Main Methods:

• Long-term experiments using the Rumen Simulation Technique (Rusitec).
• Monitoring urease activity, ammonia, volatile fatty acids, protein, and DNA.
• Controlled urea infusion and dietary variations.

Main Results:

• Initial high urease activity decreased over time, consistent with microbial dilution.
• Urease activity was restored by urea infusion, showing a direct relationship with infusion amount.
• Ureolytic activity was higher in solid-associated microbial compartments (compartment 2) than in free-floating microbes (compartment 1).

Conclusions:

• Urease activity in Rusitec is sensitive to urea availability and microbial population dynamics.
• Dietary roughage and feeding frequency impact urease activity.
• Specific urease activity is higher in the microbial suspension (compartment 1) than in solid-associated microbes (compartment 2).