ISSUE FOCUS FEED & ADDITIVE MAGAZINE July 2025 69 significant decline in feed intake, especially in lactating sows, leading to reduced milk output and compromised piglet growth (Renaudeau et al., 2011). In finishing pigs, this manifests as lower average daily gain (ADG) and poorer feed conversion ratios, extending the time needed to reach market weight. Reproductive performance also suffers. Heat stress is known to disrupt oestrous cycles, decrease farrowing rates and increase embryonic loss (Bloemhof et al., 2013). Boar fertility is also at risk, as sustained heat exposure can reduce semen quality and key fertility indicators. Beyond productivity, animal health deteriorates. Heat stress causes dehydration and electrolyte imbalances, impairs gut function, and increases pathogen susceptibility (Baumgard & Rhoads, 2013). In piglets, particularly during the weaning period, these stresses contribute to elevated mortality and suboptimal growth rates, increasing the demand for veterinary interventions and labour. THE REAL COST: ECONOMIC IMPACT ON PIG FARMS Heat stress poses a substantial economic challenge to the pig industry worldwide, leading to significant financial losses at multiple levels of production. In the United States alone, annual losses are estimated to range between $300 million and $900 million, with global figures reaching into the billions. These losses arise primarily from reduced growth rates, impaired reproductive performance, increased mortality, and the additional costs associated with managing heat stress. One of the most immediate impacts of heat stress is a marked reduction in feed intake, which can result in decreased daily gain. This slower growth translates into lighter carcass weights and diminished market value. While St-Pierre et al. (2003) reported losses of €5–10 per pig in early studies, more recent projections for Central Europe suggest similar levels — about €5.13 per pig place annually by 2030 (Schauberger et al., 2021), consistent with losses observed in the 1980s and 1990s. However, in hotter climates or less adapted systems, field reports such as Pollmann (2018) estimate losses as high as $50 to $60 (€46–55) per pig annually, underlining the growing economic risk of heat stress. For breeding herds, heat stress negatively affects sow fertility, farrowing rates and litter sizes, further compounding economic losses. The death of a sow during late gestation due to heat stress can represent a loss of around €1,000 when accounting for both the animal's value and lost productivity. Beyond direct production losses, heat stress increases pigs’ vulnerability to disease, raising veterinary costs and mortality rates. Additionally, longterm effects on offspring growth and carcass quality reduce overall herd efficiency. Producers also face higher operational expenses from investments in cooling and ventilation systems necessary to mitigate heat stress. FIVE KEY STRATEGIES TO PREVENT AND MANAGE HEAT STRESS One of the main strategies for managing heat stress is to combat and prevent the loss of electrolytes in pigs, as the heat stress results in dehydration, electrolyte loss (particularly Na⁺, K⁺ and Cl⁻) ShutterStock | Thammachak Sotiya
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