Genomic Selection Improves Heat Tolerance in Dairy Cattle.

Area of Science:

• Animal Science
• Genetics
• Climate Change Adaptation

Background:

• Dairy cattle are vital for global nutrition but vulnerable to heat stress, which reduces milk production.
• Increasing heat waves threaten the long-term security of dairy product supply.
• Breeding dairy cattle with enhanced heat tolerance is crucial for climate adaptation.

Purpose of the Study:

• To evaluate the effectiveness of genomic predictions in identifying heat-tolerant dairy cattle.
• To assess the impact of genomic selection on milk production and physiological responses during heat stress.

Main Methods:

• Utilized controlled-climate chambers to simulate a moderate heatwave event.
• Assessed Holstein cows with genomic predictions for heat tolerance (tolerant vs. susceptible).
• Monitored milk production and physiological indicators (rectal and vaginal temperatures).

Main Results:

• Genomically predicted heat-tolerant cows exhibited less decline in milk production during heat challenge.
• Physiological indicators, including rectal and vaginal temperatures, showed reduced increases in heat-tolerant cows.
• Demonstrated the efficacy of genomic predictions in differentiating heat tolerance levels.

Conclusions:

• Genomic selection is a valuable tool for identifying dairy cattle with enhanced heat tolerance.
• This approach can accelerate breeding programs for dairy herds adapted to increasing heat stress.
• Improving heat tolerance in dairy cattle contributes to securing nutrition and enhancing animal welfare.