Predicting nitrogen excretion from cattle.

Area of Science:

• Animal Science
• Environmental Science
• Agricultural Engineering

Background:

• Cattle manure nitrogen (N) contributes to environmental issues like greenhouse gas emissions and water pollution.
• Efficient N management requires precise prediction of N excretion and secretions from cattle.

Purpose of the Study:

• To develop and evaluate models for predicting fecal, urinary, and total manure N excretions, and milk N secretions in cattle.
• To improve the accuracy of N excretion predictions for various cattle classes.

Main Methods:

• A genetic algorithm was used to select predictive models for different cattle categories (lactating cows, heifers/dry cows, steers).
• Two tiers of models were developed based on input requirements, resulting in 8 new models.
• K-fold cross-validation was employed for model evaluation using all available data and recent data.

Main Results:

• Models demonstrated better prediction accuracy for total manure N and fecal N compared to urinary N.
• New models significantly improved prediction error for fecal and urinary N excretions in lactating cows compared to existing literature models.
• Both new and existing models outperformed US EPA methods for greenhouse gas inventory estimations.

Conclusions:

• The developed models offer improved accuracy for estimating manure N excretion in cattle.
• These models are recommended for use in environmental assessments and N management strategies in cattle production.
• Enhanced prediction of N excretion aids in mitigating negative environmental impacts from cattle farming.