EFFECTS OF PARAQUAT ON RUMEN MICROBIAL FUNCTION IN-VITRO

The toxicity of technical grade paraquat to rumen microorganisms was s tudied by fermentation procedures in vitro. Rumen fluid was obtained f rom a fistulated cow fed a diet of alfalfa hay. The herbicide was adde d at concentrations ranging from 0 to 1000 ppm, and incubations were c onducted for 0, 12, 24 and 48 h. Digestibility of dry matter and neutr al detergent fiber (NDF) and production of fatty acids were used to as sess microbial function. Paraquat at the different concentrations decr eased dry matter digestibility over 24 h. NDF digestibility was affect ed by 10, 100 and 1000 ppm over 12 and 24 h, whereas no effect was obs erved at 10 ppm over 48 h. Acetic acid and propionic acid productions were significantly reduced by 1000 ppm over all periods of incubations . At lower doses effects were observed after longer periods of incubat ion. Butyric acid production significantly increased at 1000 ppm over 12 h and decreased after 24 and 48 h of incubation. The results sugges ted that paraquat interferes with the digestive activity of rumen micr oorganisms in vitro. (C) 1998 Published by Elsevier Science B.V. All r ights reserved.