Knowledge of broiler heat production is traditionally based on results from climatic chambers. The advantage of such measurements is a high degree of accuracy of the results obtained under speci"c conditions; the disadvantage is that the housing conditions are often quite di!erent from those of conventional broiler production.
Broiler heat production was investigated over "ve week periods in three individual trials, each comprising two identical broiler houses with straw bedding. The investigations were based on heat and moisture balances, taking into account the following: internal and external temperatures; relative humidity; bedding temperature; internal carbon dioxide concentration; ventilation #ow; supplemental heat including light bulbs; broiler weight; feed consumption; water consumption; and animal activity. The results show that for broilers kept on deep litter (50}100 mm), the total heat production was of the same level as that given by common calculation rules, but the sensible heat production was about 17% lower than expected. Therefore, for di!erent housing systems it seems to be necessary to distinguish between the general level of &&animal'' heat production and the heat production on &&house'' level.