[Influence of agents for permanent drinking water disinfection on the fermentation performance of rumen microorganisms in ruminants].

Introduction: Good quality drinking water and adequate water intake is essential in ensuring the health of livestock. Various factors can cause the formation of a biofilm in water pipes that acts as a reservoir for many different pathogens. The addition of disinfection agents, such as chlorine dioxide or peracetic acid, is proven to improve the quality of permanent drinking water. To date this method has primarily been used in pig and poultry housing, however, it is increasingly under discussion for use in cattle husbandry. As the effects of disinfectants in drinking water on rumen fermentation are not yet known, we performed a digestibility test using the Hohenheim Feed Value Test to determine the in vitro digestibility of organic matter (IVOMD). The influence of five different concentrations of chlorine dioxide and peracetic acid disinfectants on the IVOMD of hay and wheat were tested and rumen bacteria were counted under a microscope. The use of chlorine dioxide showed no major changes in the IVOMD of hay and wheat. At the recommended concentration of 0.5 mg/l, the IVOMD relative to the control was 97,1 % for hay and 102,7 % for wheat. The number of rumen bacteria was not affected by the use of chlorine dioxide. Conversely, the use of peracetic acid led to a significant reduction in rumen fermentation. At the recommended concentration of 15-25 mg/l (dosed at 15 mg/l and 25 mg/l), the IVOMD relative to the control was 38,2 % and 38,4 % for hay and 50,4 % and 22,4 % for wheat. The number of rumen bacteria also decreased significantly. Chlorine dioxide seemed to have little to no disinfection effect on in vitro ruminal fermentation, however, the exact mechanisms could not be determined in the present study. This trial shows that disinfectants for permanent drinking water disinfection in cattle farming should be used with caution. In particular, disinfection agents containing peracetic acid may impair fermentation of rumen microbes. Further research is required to determine if the results of the present in vitro study are transferable to practice.