These changes were associated with a rise in partial net farm income and a modest reduction in CO2 emissions per kilogram of milk. Longer cow lifespans also reduced the need for replacement heifers, which has a compounding positive effect on environmental impact.

Economic inputs considered in the model included feed costs, replacement heifer costs, veterinary treatments for mastitis and lameness, and AI service expenses. A life cycle approach was used to assess greenhouse gas emissions, incorporating factors like enteric fermentation and manure management.

Sensitivity analyses confirmed that extending cow lifespan and adjusting reproduction thresholds could yield up to a 1% increase in net income and reduce emissions from 0.926 to 0.915 kg CO2-equivalent per kg of milk.

This study demonstrates that by fine-tuning reproductive strategies, dairy farms can enhance sustainability without compromising economic performance—marking a significant step forward in responsible dairy production.