Weather influences feed intake and feed efficiency in a temperate climate

Area of Science:

• Livestock science
• Animal science
• Climate change adaptation

Background:

• Global food production faces challenges from climate change, including heat waves.
• High ambient temperatures can reduce livestock dry matter intake (DMI) and milk production.
• High-yielding dairy cows are susceptible to heat stress, impacting their productivity.

Purpose of the Study:

• To investigate how feed intake and feed efficiency (FE) in dairy cows respond to natural weather variations.
• To determine if genetic merit for milk traits influences the response of feed intake and FE to weather conditions.

Main Methods:

• Utilized over 73,000 daily records from 328 lactating Holstein Friesians over 8 years in the UK.
• Compared two lines of cows: high genetic merit for milk traits (select) and UK average (control).
• Monitored feed intake and milk production in response to temperature-humidity index (THI), wind speed, and sunshine hours.

Main Results:

• Select cows showed higher milk yield, DMI, and FE than control cows.
• Both lines decreased DMI and milk yield but increased FE as THI rose.
• The increase in FE with THI was more pronounced in select cows, suggesting better heat-coping mechanisms.

Conclusions:

• Improved feed efficiency may partially mitigate reduced milk yield due to mild heat stress in dairy cows.
• Genetically selected cows may possess more effective strategies for coping with warmer conditions.
• Understanding weather impacts on feed intake and efficiency is crucial for developing climate-resilient livestock management and breeding practices.