Cows Adapted to Rising Temperatures: Farmers Utilize Genomics to Select Heat-Tolerant Breeds
Farmers are turning to genomics and cutting-edge research to address the challenges posed by rising temperatures and the impact of heat stress on dairy cattle. Traditionally, farmers have focused on genetics for milk production and quality, but with global warming, heat-tolerant cows have become more desirable.
Breno Fragomeni, an assistant professor of animal science at the College of Agriculture, Health, and Natural Resources, stresses the need to select animals for heat tolerance alongside high milk production. Failure to do so could lead to lower food production, increased food prices, and food insecurity. Additionally, prioritizing heat-tolerant breeds ensures better animal welfare.
Fragomeni and his team employ a comprehensive approach, collecting over 20 types of data – including milk production, protein and fat yields, cell count, and reproduction patterns – to determine how dairy cattle can be better adapted to heat stress. These data are compared with temperature and humidity records.
When cows experience heat stress, their milk production decreases due to reduced appetite caused by the heat. Fragomeni’s research has confirmed that for every degree above 65 on the temperature humidity index, milk production drops by 0.2 pounds per cow at the Kellogg Dairy Center. On extremely hot days, this can result in a total loss of 500 pounds of milk.
The 5% decrease in production during the summer can have significant implications for dairy farmers, who often operate on narrow profit margins. It is estimated that the dairy industry loses $1.2 billion annually due to heat stress. Furthermore, heat-stressed cows delay conception until temperatures cool down in the fall, causing calves to be born during the peak heat period. This adds to the stress experienced by the cows as they produce milk and recover from giving birth.
Addressing heat stress in cows is a complex task that cannot be solved by isolating a single gene. Fragomeni analyzes the complete genomes of bulls with numerous daughters, identifying which offspring are better equipped to handle heat. By using a sophisticated statistical model, Fragomeni associates milk production with temperature using a national database of bull genetics. This model estimates how much milk a cow is expected to lose relative to the national average based on their sire.
Without the use of genomics, it could take up to five years to determine whether a bull is genetically suitable for heat tolerance. Fragomeni’s approach enables farmers to make informed decisions about breeding, selecting sires that will produce offspring better suited for heat resilience while maintaining high milk production.
While some farmers have cooling systems in their barns, such interventions can be costly and impractical for others. Fragomeni believes that spreading heat-tolerant genetics across the entire population offers a more sustainable solution.
To further his research, Fragomeni is studying the impact of heat stress on the microbiomes of cows using milk and fecal samples from the Kellogg Dairy Center. His goal is to develop non-invasive methods for measuring heat stress. Current methods, such as blood sampling and respiration rate measurement, are invasive and cannot be easily scaled up for large-scale farms.
Fragomeni is also comparing cattle genetics between Wisconsin and Texas, two states with different climates and management systems. It is hypothesized that cows in cooler regions may be more sensitive to heat stress since they experience it for a shorter duration, unlike those in hotter regions.
The long-term objective of Fragomeni’s work is to identify the most suitable genetics for cows in each climatic region of the United States. This research aims to ensure sustainability for farmers, consumers, and the environment alike.
In conclusion, heat-tolerant breeds are increasingly crucial in the farming industry due to rising temperatures. Through genomics and advanced research techniques, scientists like Breno Fragomeni are striving to enhance the adaptability of dairy cattle to heat stress. By selecting animals based on heat tolerance alongside milk production, farmers can secure both profitability and animal welfare. This innovative approach provides an efficient and sustainable solution to combat heat stress in cows, ensuring the future resilience of the dairy industry.
