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: | , |
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| Format: | Article |
| Language: | English |
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South African Society for Animal Science
2025-07-01
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| Series: | South African Journal of Animal Science |
| Subjects: | |
| Online Access: | https://www.sajas.co.za/article/view/23023 |
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| Summary: | 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
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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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| ISSN: | 0375-1589 2221-4062 |