A modified version of the Molly rumen model to quantify methane emissions from sheep

Area of Science:

• Agricultural Science
• Animal Science
• Environmental Science

Background:

• The Molly dairy cow model's rumen submodel was adapted for sheep.
• Accurate prediction of methane emissions from ruminants is crucial for environmental impact assessment.

Purpose of the Study:

• To modify the Molly model to simulate sheep rumen function and predict methane (CH4) emissions.
• To incorporate a dynamic hydrogen (H2) pool for improved methanogenesis modeling.

Main Methods:

• Introduced a dynamic H2 pool and corrected microbial H2 utilization equations.
• Developed a function to adjust net H2 production based on intake levels.
• Calibrated and validated the model using experimental data on sheep fed temperate forages.

Main Results:

• The modified model provided reasonable methane emission estimates, particularly after parameterization.
• Model performance improved with specific parameterization for calibration and validation datasets.
• Identified feedback inhibition on H2 production and methanogen activity related to feeding levels.

Conclusions:

• The enhanced model offers a more accurate simulation of sheep rumen methanogenesis.
• Further research should investigate diet composition effects on feedback mechanisms.
• The model provides a foundation for exploring thermodynamic controls on methane production.