Behavioural Responses of Beef Cattle to Hot Conditions

Area of Science:

• Animal Science
• Climate Change Adaptation
• Livestock Management

Background:

• Rising global temperatures due to climate change increase heat load on cattle.
• Understanding cattle behavioral responses to heat is crucial for managing heat stress and ensuring animal welfare.

Purpose of the Study:

• To assess behavioral changes in Black Angus steers under heat load.
• To evaluate the impact of diet composition on heat stress behaviors.
• To identify behavioral indicators for diagnosing heat stress in cattle.

Main Methods:

• Individual exposure of 24 Black Angus steers to controlled hot conditions.
• Observation of body part positioning, feeding, body maintenance, and respiration.
• Comparison of diets: a cereal grain finisher diet versus a substituted diet with lucerne hay.

Main Results:

• Increased respiration rate correlated with increased stepping, particularly with left limbs during heat load.
• Cattle exhibited reduced eating, grooming, and scratching behaviors when exposed to heat.
• Specific postures (lowered head, backward ears, raised tail) and panting were consistent indicators of heat load.
• Cattle on the cereal grain diet showed more prolonged standing and specific ear/tail postures compared to those on the substituted diet.

Conclusions:

• Behavioral indicators such as respiration rate, stepping, and body postures can effectively detect cattle most affected by heat load.
• Substituting cereal grains with higher-fiber ingredients like lucerne hay can reduce hyperthermic behavioral responses in cattle.
• Dietary adjustments offer a viable strategy to mitigate the negative impacts of heat stress on livestock.