An Evaluation of three methods to clean feedlot water tanks

Abstract

Three methods of physically or chemically cleaning cattle feedlot water tanks were tested for their ability to reduce amounts of coliform bacteria in the water and the surface of the tank (biofilm) during the summer months: in the first method, the water tank was drained and refilled; in the second method, the water tank was scrubbed with a bootbrush to loosen and remove any visible sediment, drained and refilled; and in the third method, water tank was scrubbed with a brush (as above), drained and refilled. Household chlorine bleach (5.25% Na hypochlorite) was added to the water tank to a final 1:32 dilution. The disinfectant solution was kept in the tank for 15 minutes before the tank was drained again and refilled. In Trial 1, we found that the first and second methods did not reduce coliform bacteria in water or biofilm. On the other hand, coliform bacteria in water and biofilm were reduced 99% (p=0.0003) and 99.9% (p<0.0001), respectively, after draining, scrubbing and 15 minutes of chemical disinfection with chlorine bleach and refilling (method 3). However, coliforms returned to pretreatment levels 24 hours after treatment (p=0.12). In Trial 2, we demonstrated that the rapid re-population in coliform bacteria was due to the cattle drinking from the tanks (p=0.0003). These data indicate that coliform bacteria rapidly re-populate water tanks in the summer because cattle re-contaminate them with coliform bacteria and/or substrate. If the overall number of coliforms in a water tank reflects the likelihood of transmitting coliform bacteria from water tanks to cattle, then the benefits of cleaning and disinfecting water tanks to minimize the transmission of coliform bacteria to cattle are short-lived.