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For many years the assumption was made that gases present in the atmosphere of total confinement livestock units tend to accumulate at different levels depending on their relative densities. Specific ventilation recommendations with regard to the effective removal of gases were based on this premise. However, Noren et al. (9), in a field study involving a range of livestock units, found that this stratification did not occur. Subsequent studies (3, 4, 10) have substantiated this finding. Heavy and light gases were shown to have similar distribution patterns whereas gas concentrations were dependant on the ventilation rate. Gas diffusion was found to take place as a consequence of temperature gradients, air movement, and diffusion. Gases in confinement units result primarily from respiration of the animals, from fermentation in the case of ruminants, and from biological degradation of animal waste products. The gases commonly involved include carbon dioxide (C02), methane (CH4 ), ammonia (NH ), and hydrogen sulfide (H2 S). As production of gases by the animals could be expected to remain fairly constant, any major variation in the gases generated within confinement units logically might be assumed to be due to the system of housing and waste-handling method employed.
effects of beef housing systems on gaseous contaminants removed by ventilation
Feddes, J.J.R. and J.B. McQuitty 1973. EFFECTS OF BEEF HOUSING SYSTEMS ON GASEOUS CONTAMINANTS REMOVED BY VENTILATION. Canadian Agricultural Engineering 15(2):119-123.
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