Hot weather increases competition between dairy cows at the drinker

Area of Science:

• Animal Science
• Environmental Physiology
• Dairy Husbandry

Background:

• Heat stress negatively impacts dairy cows, affecting resource competition.
• Understanding heat stress effects on indoor-housed cows' drinking behavior is crucial.

Purpose of the Study:

• To evaluate how heat stress influences drinking behavior and competition at water sources in indoor-housed dairy cows.
• To analyze group and individual cow-level responses to heat stress at the drinker.

Main Methods:

• Observational study over 59 days with 69 lactating Holstein cows.
• Electronic water bins monitored time, frequency, intake, and competitive events (replacements).
• Temperature-Humidity Index (THI) correlated with drinking behavior using linear regression and mixed models.

Main Results:

• Increasing THI led to increased water intake, time at drinker, visits, and competitive events.
• Cows with low competitive success altered drinking patterns, avoiding peak heat times.
• Drinking behavior changes indicate thermal stress in dairy cows.

Conclusions:

• Dairy cow drinking behavior, including competition and avoidance, is a reliable indicator of heat stress.
• Monitoring drinker attendance can help determine optimal times for cooling interventions.
• Behavioral responses provide practical insights for managing heat-stressed indoor dairy cows.