[Effects of orally administered therapeutic drugs on the fermentation processes in the rumen fluid of ruminating cattle (in vitro). 6. Copper sulfate].

In 50 trials, incubating rumen fluid at 39 degrees C for 6 hours with starch and urea as nutrients, the effects of simulated oral administration of 3 g copper sulphate per animal and day (50 mg copper sulphate per liter rumen fluid) on rumen fermentation patterns have been examined. In two series of five incubations each in rumen fluid of five donors (total = 50), doses of 2.25 g (37.5 mg/l) and 4.5 g (75 mg/l) copper sulphate were simulated. The five donors (517-720 kg) of ruminal fluid were fed a ration of hay and concentrate twice daily and water was offered ad libitum. Rumen fluid was sampled 2.5 hours after feeding in the morning and immediately incubated in the artificial rumen. While at 2.25 g an effect was hardly seen and 4.5 g were followed by great changes, 3 g appeared to be the limiting dose that reduced the amylolysis (-23.9%; p < 0.001), the production of volatile fatty acids (-23.5%; p < 0.001) and methane (-23.6%; p < 0.001), but caused a higher concentration of ammonia (+11.2%; p < 0.001). Therefore 2 g CuSO4/animal/day is recommended as maximum dose in cattle to overcome Cu-deficiency.