Microbiological, chemical and physical quality of drinking water for commercial turkeys: a cross-sectional study

Drinking water for poultry is not subject to particular microbiological, chemical and physical requirements, thereby representing a potential transmission route for pathogenic microorganisms and contaminants and/or becoming unsuitable for water-administered medications. This study assessed the microbiological, chemical and physical drinking water quality of 28 turkey farms in North-Eastern Italy: 14 supplied with tap water (TW) and 14 with well water (WW). Water salinity, hardness, pH, ammonia, sulphate, phosphate, nitrate, chromium, copper and iron levels were also assessed. Moreover, total bacterial count at 22°C, presence and enumeration of Enterococcus spp. and E. coli, presence of Salmonella spp. and Campylobacter spp. were quantified. A water sample was collected in winter and in summer at 3 sampling sites: the water source (A), the beginning (B) and the end (C) of the nipple line (168 samples in total). Chemical and physical quality of both TW and WW sources was mostly within the limits of TW for humans. However, high levels of hardness and iron were evidenced in both sources. In WW vs. TW, sulphate and salinity levels were significantly higher, whilst pH and nitrate levels were significantly lower. At site A, microbiological quality of WW and TW was mostly within the limit of TW for humans. However, both sources had a significantly lower microbiological quality at sites B and C. Salmonella enterica subsp. enterica serotype Kentucky was isolated only twice from WW. Campylobacter spp. were rarely isolated (3.6% of farms); however, Campylobacter spp. farm-level prevalence by real-time PCR was up to 43% for both water sources. Winter posed at higher risk than summer for Campylobacter spp. presence in water, whereas no significant associations were found with water source, site, recirculation system, and turkey age. Low salinity and high hardness were significant risk factors for C. coli and C. jejuni presence, respectively. These results show the need of improving sanitization of drinking water pipelines for commercial turkeys.