Occurrence of Coliforms and Enterococcus Species in Drinking Water Samples Obtained from Selected Dairy Cattle Farms in Portugal

Microbial water quality is a major concern in the world, since the ingestion of water contaminated with microorganisms poses risks to human and animal health. The aim of this study was to evaluate the microbiological quality of drinking water on dairy cattle farms. The study was carried out to determine the occurrence of coliforms and enterococcus species in drinking water samples obtained from selected dairy cattle farms located in four different areas of Portugal (north, central, south and islands). A questionnaire was used to collect relevant information regarding farmer demographics, characteristics of the cattle farms, as well as number of animals per herd, number of adult cows, production type, water source, use of disinfectants and pasture area. In this study, a convenience sample of 32 dairy cattle farms was subjected to screening for water quality. The numbers of animals in the study were 8086 cattle, with a mean herd size of 253, of which 51.7% were cows. Coliform and enterococcus bacterial species were identified by performing the membrane filtration method. The occurrence of poor water quality was recorded in 19 (59.4%) cattle farms. Isolated bacteria included Escherichia coli (20.0%), Enterococcus faecalis (25.0%), total coliforms (65.6%) and fecal coliforms (43.8%). Farms that did not routinely perform disinfection had the worst water quality (70.8%) when compared with farms that performed disinfection (25.0%) (p = 0.022). This research revealed the importance of screening the quality of drinking water on cattle farms, which could contribute to improved animal, human and environmental health in a One Heath approach.