Heat waves have increased in intensity and frequency over the past 60 years. Heat waves are more frequent and intense in America today than they were 60 years ago. The average heat season is 46 days longer. Temperatures are hovering around 2.5 degrees F (1 degree C), above the local threshold.
Spring temperatures increased by 2°F (1°C), compared to an increase of 1.6°F (0.88°C) in the summer and fall. This suggests that it is now warmer at the height of the dairy season. During the peak dairy season, temperatures in the major dairy states in the Northeast and Southwest are also higher. Temperature changes to the most extreme levels.
Two experts were interviewed to find out what's next for the dairy industry in terms of heat stress and how to combat it. They also provided information on available resources.
Peri Rosenstein, a veterinarian, is the senior livestock systems scientist at the Environmental Defense Fund.
Ananda Fontoura, a Cornell University veterinarian and postdoctoral associate in animal sciences and an expert in nutrition and environmental physiology, is an expert.
DR: What are some of your key observations regarding heat stress in cows over the last decade? Over the last few years, what are your key observations regarding heat stress in cows?
Peri Rosenstein:Heat stress is known to reduce milk production and dry matter intake. It can also reduce reproductive efficiency, cause morbidity in cows and compromise their general welfare. These responses are exacerbated by increased heat indices combined with the currently high metabolic rate in dairy cows.
Ananda Fontoura:Heat stress has had a significant impact on cow health in recent years.
There is ample evidence and research that exposing dairy cows to higher than normal temperatures triggers behavioral changes aimed at maintaining comfort and reducing heat loads.
They adjust their rest and physical activity habits to increase heat dissipation and seek shade.
Cows exposed to high temperatures will immediately respond to heat stress by increasing their body temperature. Cows reduce their feed intake in an attempt to minimize metabolic heat production. Reducing feed intake has a significant impact on energy, milk production, and reproduction.
Recent research supports the hypothesis that heat stress compromises gastrointestinal barrier functions, allowing harmful bacterial products, such as endotoxins, to be transferred into the bloodstream. Physiological stress is exacerbated by this ordeal, which can negatively impact the health of dairy cows.
Which regions of the United States have suffered the most from heat stress? Are there any signs that heat stress has started to affect more dairy farmers in states that weren’t as affected before?
AF:Heat stress has historically been the worst in the Southern states. This includes (but is not limited to) Florida, Texas, and Arizona. Forecasts estimate a temperature increase of up to 2.7 degrees F (1.5 degrees C) in cool areas. This is also a major concern because in already very hot areas, temperatures could reach 9 degrees F (5 degrees C).
PR:The impacts are also visible in beef production. As a result, many beef cattle in Iowa, Kansas and Nebraska died last summer due to the heat index.
What do climate models predict about the impact of global warming on U.S. dairy products in the coming years?
PR:Climate change models show that significant reductions in carbon dioxide and methane emissions are needed to reduce the rate of warming over the coming decades. We are currently seeing a gradual increase in temperatures around the world, which will continue to impact the U.S. dairy sector due to heat stress.
AF:You can also read more about the A-Team here. IPCC 2021 ReportIf greenhouse gas emissions do not decrease, global temperatures are projected to rise by as much as 8.8 degF / 4.8 degC) by 2100. In addition to rising temperatures, extreme heat and cold events are becoming more common in North America.
The adverse effects of heat are expected to increase over time. This is of particular concern to U.S. dairy producers because high-producing cows have higher metabolic rates and are therefore more susceptible to the impacts of global warming.
What is the impact of heat on dairy cows in terms of milk loss and preparation costs?
AF:Heat stress is a significant economic problem for the U.S. dairy industry. It costs between $1 billion and $2.5 billion annually. This financial impact could increase by $126 million over the next fifty years, according to projections. Economic losses can be attributed to decreased milk production, increased pregnancy rates, higher prevalence of diseases, and even death of dairy cows.
How can industry, government and producers respond to extreme heat challenges in the dairy industry?
PR:Producers will need to adapt and continue to evolve to address the impacts of climate change. Further research into heat stress reduction strategies is also needed.
DR. How effective are traditional methods for managing heat stress in dairy cows in today’s volatile weather conditions? What information should dairy producers have to better prepare for extreme weather?
AF:Conventional approaches to mitigate the adverse effects of heat stress focus on heat-reducing techniques such as fans and sprinklers. These measures, while highly effective, are costly and require many resources, such as water and energy, which are not always available in some parts of the world.
Heat stress poses a continuing challenge to cow health, welfare and fertility. There is an urgent need to find alternative methods to help heat-stressed cattle maintain productivity and welfare.
PR:You can use a number of different interventions, such as ventilation, fans, sprays, and cooling devices.
What will be the impact of this summer on milk production? Especially in terms of heat stress and other factors, such as avian flu outbreaks or the impact of high temperatures on dairy farms.
PR:Dairy farm productivity is highly unpredictable. It is influenced by many factors, including typical summer variations, global temperature records, disease outbreaks and how they are responded to. These factors can reduce milk production, but the extent of the reduction is highly variable.
What is the state of U.S. dairy production so far this summer?
The USDA reported in June that milk production was 0.8 % lower in major U.S. states than in previous years. Average production per cow was 2,025 pounds in June. That's 8 pounds less than the previous year.
Arizona, California and Colorado are the 24 states. Then come Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, New Mexico, New York, Ohio, Pennsylvania, South Dakota, Texas, Utah, Vermont, Virginia, Washington, Wisconsin
The next USDA update is expected in August 2024.
English 
French