THE EFFECT OF TIMING OF FLOOR-APPLICATION OF MINERAL-OIL ON DUST CONCENTRATIONS IN A SWINE FARROWING UNIT

Three farrowing rooms, each housing 5 sows and litters, were used to s tudy the effects of floor-applied mineral oil on dust concentrations ( >0.5 mu m diameter). Rooms were ventilated at a similar rate (266 L/s) . Three treatments were considered over a 3-week duration: oil was app lied on day 8, 15, and 22; oil was applied only on day 8; and no oil w as applied. Oil applied to pen floors at a rate of 24 mL/m(2) using a low-pressure hand sprayer was found to be effective. Dust concentratio ns (particles/mL), wet and dry-bulb temperatures, ventilation rate, an d total piglet mass per room were recorded on day 9, 16, and 23 in eac h treatment. At day 23, dust concentrations 24 h before measurement we re 0.8 particles/mL, oil applied only on day 8 were 5.5 particles/mL, and the concentration when no oil was applied was 5.6 particles/mL. Th e greatest increase in dust concentration occurred between weeks 2 and 3 when growth rate of the piglets was most rapid. Applying oil 24 h b efore measurement resulted in an average dust reduction of 73%. At wee k 3, the respirable particle production rates were 5, 25, and 30 parti cles/s per pig for oil applied 24 h and 15 d before measurement and no oil application, respectively.