Livestock drinking water microbiology and the factors influencing the quality of drinking water offered to cattle

The microbial, quality of livestock drinking water was evaluated in 473 cat tle water troughs located at 99 different cattle operations. The mean log(1 0)-transformed coliform and Escherichia coli concentrations per milliliter of trough water were 1.76 +/- 1.25 (SD) and 0.98 +/- 1.06 (SD), respectivel y. The degree of E. coli contamination was positively associated with the p roximity of the water trough to the feedbunk, protection of the trough from direct sunlight, lower concentrations of protozoa in the water, and warmer weather. Salmonella sp. were isolated from 2/235 (0.8%) troughs and shigat oxigenic-E. coli O157 was recovered from 6/473 (1.3%) troughs. Four experim ental microcosms simulating cattle water troughs were used to further evalu ate the effects of protozoal populations on the survival of E. coli O157 in cattle water troughs. Escherichia coli O157 of bovine fecal origin prolife rated in all microcosms. Reduction of protozoal populations by treatment wi th cycloheximide was associated with increased persistence of E. coli O157 concentrations in the microcosms. Water troughs are a major source of expos ure of cattle to enteric bacteria, including a number of foodborne pathogen s, and this degree of bacterial contamination appeared to be associated wit h potentially controllable factors.