Terminal disinfection of calf houses by formaldehyde fumigation.

Trials were carried out to investigate the effectiveness of various methods of formaldehyde fumigation as a means of disinfecting calf houses. Houses were cleaned by the farmer, sealed and then fumigated. A significant reduction in bacterial numbers was obtained when the gas was produced by heating paraformaldehyde, mixing formalin with potassium permanganate or boiling formalin in calf houses that could be effectively sealed. Aerosol generators did not give satisfactory results. Efficient pre-cleaning and sealing of the houses were of paramount importance; relative humidity and temperature were less important.