Although the dairy industry wants a free pass for carbon emissions, some scientists are looking for ways to help it cope with a warming climate.
By Brendan Borrell
In July 2006, a monthlong triple-digit heat wave scorched California, killing more than 25,000 cattle and reducing dairy production in the region. Land O’Lakes Creameries, which normally produces six million liters of milk daily, was short 1.5 million liters per day. All told, experts estimate that the high temperatures caused $1 billion worth of dairy shortfalls.
Extreme weather events and higher average temperatures are predicted to increase with global warming, and that’s bad news for livestock producers in the U.S. and abroad. Warming will reduce grass, brush and other forage available in many areas, and it will also directly influence cows’ physiology. Dairy production is optimal at cooler temperatures between 20 to 22 degrees Celsius, explains Terry Mader of the University of Nebraska–Lincoln. “For every degree above that,” he says, “we’ll have a decline of approximately 2 percent productivity.”
Mader is one of many scientists studying the potential impacts of climate change on livestock, and how producers can mitigate them. He says that although climate models are not conclusive about whether the U.S. Midwest’s average temperature will go up 2 degrees C or 5 degrees C over the next century, the physics of cows is pretty straightforward. “You have heat generated from metabolism and digestion, and then they have to cope with the environmental component,” he explains, “How do they offset increased heat? They eat less.” The decline in feeding results in a decline in output, whether that’s meat, milk or fur. They also tend to have lower rates of conception during warmer months. “That’s just physiology,” Mader says.
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