Understanding the impact of changes in the environment on the nutritional and physiological status of the pig will facilitate development of appropriate environmental management and feeding strategies (DeShazer, 1982). The objective of this study was to characterise the nutritional and physiological responses of growing pigs, with particular emphasis on effects on acid–base and thermal homeostasis, when exposed to a diurnal pattern of heat stress. It was found that a diurnal pattern of heat stress fluctuating between 20°C and 38°C within 24 h did not affect mineral
metabolism in growing pigs and had limited effect on acid–base balance. Therefore, pigs have the ability to recover from the effects of heat stress if periods of heat stress are followed by periods of thermal comfort. The diurnal pattern of heat stress had an effect on the physiological status of pigs resulting from the mechanisms (e.g., increased respiration rates) used to maintain thermal homeostasis and associated renal compensation. Therefore, strategies for managing pigs exposed to heat stress should focus on ways (e.g., provision of cool drinking water) of enhancing the pig’s ability to dissipate excess body heat, and should recognise the impact of thermal stress on acid–base parameters.