Effect of technical grade pentachlorophenol on rumen microorganisms.

The toxicity of technical grade pentachlorophenol to rumen microorganisms was tested by an in vitro fermentation procedure. Rumen fluid was collected from a fistulated mature steer fed a diet of all alfalfa hay. The compound was dissolved in absolute ethanol and added in vitro at concentrations ranging from 0 to 100 ppm. Digestion of cellulose and production of volatile fatty acids over 24 and 48 h of incubation was used to assess toxicity. Both cellulose digestion and propionic acid production were decreased at the 10 ppm concentration. The results suggest that technical grade pentachlorophenol has the potential to interfere with utilization of cellulose in ruminants.