Copper Sulfate-induced Fermentation Changes in Continuous Cultures of the Rumen Microbial Ecosystem1

The effect of CuSO4 on fermentation was studied in a continuously cultured rumen ecosystem. CuSO4, introduced at a level of 50 mg/500 ml of culture volume twice daily, caused a marked inhibition of fermentation of concentrates. Fermentation of alfalfa hay was not inhibited by the same CuSO4 concentration when the inoculum for the culture was obtained from a cow maintained on a normal concentrate ration. When the inoculum was from a cow on a high concentrate ration, hay fermentation was partially inhibited by CuSO4. Concentrations of CuSO4 that did not inhibit the fermentation of alfalfa hay or hay-concentrate mixtures caused preferential production of propionic acid and decreased production of methane.