Heat and moisture production of modern swine

The total heat and moisture production (THP and MP) values of pigs that are currently published in ASHRAE standards are from data collected in either the 1970s (nursery piglets) or the 1950s (growing-finishing pigs). These series of studies, conducted to systematically update the THP and MP standards, includes a series of four indirect calorimeter studies (nursery, growing-finishing gilts, and finishing barrows), and six facility-level studies (nursery, growing, early finishing, late finishing, gestating gilts, and farrowing sows and litters). The studies were completed at various temperatures from thermal neutral to hot conditions, demonstrating the trends that HP and feed intake decreased while MP increased as environmental temperature increased. Overall, THP was observed to be 16% higher than current standards. To predict MP from the entire facility rather than just the animals, the waste-handling systems, sprinkler cooling systems, and nonvented gas-fired heaters were monitored and found to contribute significantly to the overall MP. Continuous measurements showed a diurnal THP pattern that was higher during light periods than during dark periods, with peaks just after lights came on and just before lights went off These updated THP and MP values are essential in designing new and managing current swine facilities.