Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics

Heat stress has been identified as one of the major challenges for livestock production. Global temperatures are steadily increasing, with South African temperatures increasing at nearly twice the global rate. Of the livestock used for food production, dairy cows are the most sensitive to thermal c...

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Main Authors: LM Erasmus, E van Marle-Köster
Format: Article
Language:English
Published: South African Society for Animal Science 2025-07-01
Series:South African Journal of Animal Science
Subjects:
Online Access:https://www.sajas.co.za/article/view/23023
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author LM Erasmus
E van Marle-Köster
author_facet LM Erasmus
E van Marle-Köster
author_sort LM Erasmus
collection DOAJ
description Heat stress has been identified as one of the major challenges for livestock production. Global temperatures are steadily increasing, with South African temperatures increasing at nearly twice the global rate. Of the livestock used for food production, dairy cows are the most sensitive to thermal changes, which have detrimental effects on their health, welfare, and overall productivity. Several abiotic factors that influence the heat load experienced by the cow are not commonly included in thermal indices used to measure heat stress; these include solar radiation, wind speed, and soil quality. Furthermore, the thermal comfort zone of cows has been altered by years of intense selection for increased milk yield, causing cows to become heat stressed at lower temperatures. Considering the abiotic and biotic factors affecting the cow’s heat load, it can be argued that dairy cows in tropical and subtropical climates are experiencing constant heat stress. In this review, the abiotic and biotic factors influencing the heat load experienced by dairy cows are reviewed, along with the available thermal indices that can be utilised at farm level. Submitted 27 August 2024; Accepted 27 November 2024; Published January 2025 ------------------------------------------------------------------ Significance of research to South African science The research addresses the escalating impact of heat stress on dairy cows in a country experiencing rising temperatures at nearly twice the global rate. With most of South Africa’s dairy production relying on pasture-based systems, the review highlights the vulnerability of local herds to both environmental and physiological stressors. It evaluates the limitations of conventional thermal indices like THI and advocates for cow-specific and regionally relevant measures, while also exploring genetic adaptations such as the SLICK1 allele to improve heat tolerance. The study provides vital insights for climate-resilient livestock management, sustainable dairy production, and future research and policy aimed at safeguarding food security and rural livelihoods under climate change.
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spelling doaj-art-962f04fed16e44f0bb70e52b6a37d55e2025-08-20T03:09:43ZengSouth African Society for Animal ScienceSouth African Journal of Animal Science0375-15892221-40622025-07-0155110.4314/sajas.v55i1.02Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropicsLM Erasmus0https://orcid.org/0000-0002-2364-5886E van Marle-Köster1https://orcid.org/0000-0002-3672-6976University of PretoriaUniversity of Pretoria Heat stress has been identified as one of the major challenges for livestock production. Global temperatures are steadily increasing, with South African temperatures increasing at nearly twice the global rate. Of the livestock used for food production, dairy cows are the most sensitive to thermal changes, which have detrimental effects on their health, welfare, and overall productivity. Several abiotic factors that influence the heat load experienced by the cow are not commonly included in thermal indices used to measure heat stress; these include solar radiation, wind speed, and soil quality. Furthermore, the thermal comfort zone of cows has been altered by years of intense selection for increased milk yield, causing cows to become heat stressed at lower temperatures. Considering the abiotic and biotic factors affecting the cow’s heat load, it can be argued that dairy cows in tropical and subtropical climates are experiencing constant heat stress. In this review, the abiotic and biotic factors influencing the heat load experienced by dairy cows are reviewed, along with the available thermal indices that can be utilised at farm level. Submitted 27 August 2024; Accepted 27 November 2024; Published January 2025 ------------------------------------------------------------------ Significance of research to South African science The research addresses the escalating impact of heat stress on dairy cows in a country experiencing rising temperatures at nearly twice the global rate. With most of South Africa’s dairy production relying on pasture-based systems, the review highlights the vulnerability of local herds to both environmental and physiological stressors. It evaluates the limitations of conventional thermal indices like THI and advocates for cow-specific and regionally relevant measures, while also exploring genetic adaptations such as the SLICK1 allele to improve heat tolerance. The study provides vital insights for climate-resilient livestock management, sustainable dairy production, and future research and policy aimed at safeguarding food security and rural livelihoods under climate change. https://www.sajas.co.za/article/view/23023climate changeheat loadHolstein cattleJersey cattlethermal indices
spellingShingle LM Erasmus
E van Marle-Köster
Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
South African Journal of Animal Science
climate change
heat load
Holstein cattle
Jersey cattle
thermal indices
title Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
title_full Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
title_fullStr Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
title_full_unstemmed Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
title_short Heat stress in dairy cows: A review of abiotic and biotic factors, with reference to the subtropics
title_sort heat stress in dairy cows a review of abiotic and biotic factors with reference to the subtropics
topic climate change
heat load
Holstein cattle
Jersey cattle
thermal indices
url https://www.sajas.co.za/article/view/23023
work_keys_str_mv AT lmerasmus heatstressindairycowsareviewofabioticandbioticfactorswithreferencetothesubtropics
AT evanmarlekoster heatstressindairycowsareviewofabioticandbioticfactorswithreferencetothesubtropics