Reducing the Water Footprint of Milk in Current and Future Climates

Project Overview

This research addressed key priorities for the dairy sector, including sustainable water and effluent management and adaptation to climate change. The project aimed to understand dairy-farm water use, examine heat stress indicators, and use global climate data to model potential impacts of climate change on heat stress in the future.

What Did the Research Team Do?

Measured in-barn water use: Extensive data were collected on the amount of water used for cleaning and drinking.
 
Examined runoff around dairy farms: Bunker silo effluent was examined to better understand its impact on local phosphorus load and the utility of a novel slag filter on a farm in southern Ontario.
 
Measured and projected indicators of heat stress: Temperature and humidity sensors were installed in and around barns across nine farms to compare indoor and outdoor conditions; climate change scenarios and historical weather data were used to project estimated indicators of heat stress until 2080; and assessments were conducted to evaluate heat stress mitigation and reduction strategies.

What Did the Research Team Find?

In-barn water use:

• Water use benchmarks (L water used / Kg milk produced) were developed for summer and winter and for tie-stall, milking parlors, and robotic milking systems
• Updated benchmarks for milking systems showed tie‐stall barns used 21.8 L/cow/day; milking parlors used 25.8 L/cow/day, and robotic milking systems used 40.3 L/cow/day, on average.

Runoff around dairy farms:

• Collection and treatment of bunker silo runoff with a slag filter (iron with gravel pit) has been shown to be highly effective and durable.

Heat stress:

• Barn design influenced how fast barns cool down in the evening; mechanically ventilated and insulated barns were cooler.
• Climate change models show substantial increase in the number of days of in‐barn heat‐stress conditions in 2050s and 2070s at all locations.
• Both historical observations and future projections indicate the largest increases in the magnitude and duration of heat stress occur in Ontario.

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