Livestock Heat Stress: Welfare in a Warming Climate

How rising global temperatures are intensifying heat stress in farm animals and what management adaptations protect welfare.

Key Facts

Heat stress in dairy cows begins at a temperature-humidity index (THI) above 68 — a threshold exceeded regularly in many farming regions
Heat-stressed dairy cows produce 10–25% less milk, have reduced conception rates and elevated cortisol levels
Poultry are particularly vulnerable — broiler and laying hen mortality spikes dramatically above 35°C
Pigs cannot sweat and rely entirely on respiratory heat loss — heat stress manifests rapidly and severely
Shade, sprinklers and forced ventilation reduce heat stress but require capital investment that small producers may lack
Climate projections suggest heat stress events will double in frequency in Europe by 2050

Welfare Considerations

Heat stress causes immediate, measurable welfare harm — reduced feed intake, increased respiratory rate, prostration, elevated body temperature and in severe cases death from hyperthermia. As climate change pushes ambient temperatures higher and extends the duration of hot periods, what were once exceptional heat events are becoming routine. Livestock breeding programmes optimised for cool temperate climates are poorly adapted to these conditions. Welfare-aligned adaptation requires both immediate management responses — shade, ventilation, water availability — and longer-term strategic changes including breed selection for heat tolerance and farm design for passive cooling. These are not optional enhancements — they are welfare necessities for animals that cannot choose their environment.

What You Can Do

Install shade structures, ventilation fans and sprinkler systems in livestock housing before summer heat events, not during
Ensure continuous fresh water access during hot periods — heat-stressed animals drink two to three times their normal water volume
Adjust feeding management during heat events — feed at cooler times of day to reduce metabolic heat generation
Monitor temperature-humidity index daily during summer and implement heat protocols at THI 68 for cattle
Work with your vet to develop a heat emergency protocol including identification of animals at highest risk
Advocate for breed improvement programmes that incorporate heat tolerance alongside production traits