Heat stress in goat (Capra hircus): Impacts on physiological responses, production, and reproduction

Goats (Capra hircus) are vital to global agriculture and food security, sustaining over 1 billion livelihoods, particularly in arid and semi-arid regions. However, climate change has intensified heat stress (HS), threatening productivity, welfare, and economic viability. This review synthesizes four decades of research to elucidate the impacts of HS and evaluate mitigation strategies. HS disrupts homeostasis, reducing feed intake, impairing metabolic efficiency, and altering endocrine function. Reproductive performance declines by 30–50% in subtropical breeds due to suppressed oestradiol, follicular atrophy, and embryonic mortality. Indigenous breeds exhibit resilience via upregulated heat shock proteins (HSP70) and metabolic flexibility, whereas high-yielding breeds face severe milk yield losses (50% at THI >85) and carcass quality deterioration. Behavioural adaptations, such as shade-seeking and nocturnal grazing, mitigate heat load but reduce feeding efficiency. Nutritional interventions (e.g., antioxidants) and environmental modifications (such as shade and cooling systems) can alleviate stress, although their efficacy varies by breed and dosage. Phytochemicals, such as thyme-garlic blends, reduce oxidative stress by 50%, while melatonin supplementation stabilizes reproductive hormones. Chronic HS alters blood transcriptomics, suppressing immune pathways and metabolic homeostasis. Transport under HS exacerbates mortality risks and declines in meat quality, necessitating improved handling protocols. Effective strategies require integrating genetic selection, nutritional optimisation, and policy initiatives to support smallholder farmers. This review highlights the importance of interdisciplinary collaboration in safeguarding goat production in a warming climate.