PSIX-8 - Drinking water acidification and chlorination improves microbiological water quality without detrimental effects on performance or hazard side-effects in bulls fed high-concentrate diets

The aim of this study was to evaluate the effect of drinking water disinfection (chlorination) and conditioning (acidification) on microbiological water quality, water and feed consumption, total tract apparent digestibility and its potential hazard effects on animal health in Holstein bulls fed high-concentrate diets. Twenty-four Holstein bulls (221 ± 20.9 kg of initial BW, and 184 ± 9.9 d of age) were housed individually and fed ad libitum. Animals were assigned to 4 treatments with a 2 x 2 factorial design: drinking water conditioning (with or without acidification) and disinfection (absence or chlorination). Every 28 d, water samples from the tank and drinker were collected to analyze pH, residual chlorine and microbial load. Water consumption was recorded daily, and every 2 wks feed consumption and BW were recorded. At d 0, 14, 98 and 196 blood samples were collected to hematology and clinical chemistry analysis. At d 42 and 147 total tract apparent digestibility was estimated. Data were analyzed with a mixed effects model. In the tank, acidification increased residual free chlorine (0.58 vs. 0.33 ± 0.081 ppm, interaction, P = 0.10) and chlorination reduced (P < 0.01) total coliform count (0.8 vs. 392.7 ± 0.30 CFU / 100 ml) and Clostridium perfringens count (0.0 vs. 9.0 ± 0.13 CFU / 100 ml). In the drinkers, chlorination only tended (P = 0.10) to decrease total coliform count (967.5 vs. 994.7 ± 0.01 CFU / 100 ml). Treatments did not affect daily water consumption, total DMI nor blood parameters. At the end of the study, chlorination tended (P = 0.07) to improve starch total apparent digestibility (98.2 vs 97.7 ± 0.28 %). In fattening bulls’, the conditioning (acidification) and disinfection (chlorination) of drinking water improved its microbiological quality without detrimental effects on water and feed consumption, ruminal digestibility or hazard side-effects.