Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2002
Publication Date: N/A
Technical Abstract: The impact of thermal stress on survival and productivity is evident in all stages of swine production. Thermal stress is associated with reduced survival of the neonate, poor reproductive performance in sows and boars, and poor growth and carcass quality in finishing pigs. Thermal stress invokes numerous changes in the pig's metabolism, behavior, and endocrine system. While the primary causes of neonatal mortality have been attributed to crushing, starvation, and disease, the actual causes of mortality may be more closely linked with one another than previously believed. Piglets with disease and nutritional problems experience chilling and express altered behaviors that increase the likelihood of being crushed. Neonatal pigs have a limited ability to cope with environmental stressors, thus predisposing them to relatively high rates of morbidity and mortality. In older pigs, exposure to heat stress hinders performance and productivity. At high ambient temperatures, sufficient feed intake by the sow is likely a greater concern for piglet survival and performance. Exposure to ambient temperatures greater than 25 deg C decreases intake in lactating sows, reducing milk production and associated piglet growth. In boars, heat stress has been shown to alter reproductive efficiency and capabilities. Finally, in finisher pigs, heat stress reduces growth rate and alters carcass composition. Therefore, heat stress not only reduces overall productivity in finishing pigs, but also reduces the value of the final product. Given the associated economic losses, continued research on the interactions among thermal stress, nutritional requirements, immunological status, and overall performance are undoubtedly needed and warranted.