Heat stress risks to dairy cattle welfare and milk production in Goiás, Brazil under high-resolution climate change scenarios

Abstract

Context Climate change poses a significant threat to dairy production systems, particularly in tropical regions where rising temperatures and humidity intensify heat stress in cattle, such as Goiás (Brazil). Heat stress compromises animal welfare, productivity, and farm sustainability, necessitating regional-scale impact assessments using high-resolution climate projections. Objective This study aimed to assess the future impacts of climate change on dairy cattle welfare and milk production in Goiás, Brazil, under intermediate (RCP4.5) and high-emissions (RCP8.5) scenarios across short- (2021–2040), medium- (2041–2060), and long-term (2061–2080) horizons. Methods High-resolution (5 km) climate projections from the Eta Regional Climate Model, driven by HadGEM2-ES, were used to extract daily air temperature and relative humidity. Heat stress was quantified using the Temperature–Humidity Index (THI), with severe stress defined as THI > 78. Animal welfare impacts were evaluated by calculating the seasonal number of days with severe THI (ndaysTHI). Milk production losses were estimated using the Milk Production Decline (MPD) index for moderate-producing (25 kg·cow −1 ·day −1 ) and high-producing (40 kg·cow −1 ·day −1 ) herds. Seasonal analyses were conducted for DJF (summer), MAM (autumn), JJA (winter), and SON (spring), comparing future projections with a historical baseline (1986–2005). Results and conclusions All future scenarios projected significant increases in air temperature (up to +7 °C under RCP8.5 by 2061–2080) and reductions in relative humidity (locally exceeding −25%). Consequently, THI values increased statewide, with anomalies reaching up to +6 units by the late century under RCP8.5. The number of days with severe heat stress (THI > 78) increased progressively throughout the century. Under RCP8.5 (2061–2080), seasonal increases exceeded 70 additional severe-heat days in some regions, indicating near-continuous exposure during spring and summer. The northwestern region consistently emerged as the most vulnerable hotspot. Milk production losses intensified proportionally to productivity level. Under historical conditions, MPD reached up to 4 kg·cow −1 ·day −1 for moderate-producing cows and 7 kg·cow −1 ·day −1 for high-producing cows. Under RCP8.5 (2061–2080), projected declines reached up to 10 kg·cow −1 ·day −1 in high-producing herds, with losses occurring across all seasons. Even under RCP4.5, significant late-century intensification of production losses was observed. Climate change is projected to transform heat stress in Goiás from a predominantly seasonal constraint into a chronic, year-round challenge, particularly under high-emission scenarios. The substantial increase in severe heat stress days and associated milk production declines—especially in high-producing systems—poses serious risks to animal welfare, productivity, and regional sustainability. The northwestern region represents a critical vulnerability hotspot. Significance These findings highlight the urgent need for integrated adaptation strategies, including improved housing and cooling systems, shade management, genetic selection for thermotolerance, and precision livestock technologies to ensure climate-resilient dairy production in tropical regions.

The authors' abstract, as published at the source. Agricultural Systems, 2026 · DOI ↗