STUDIES OF THE EFFECT OF ORALLY-ADMINISTE RED SUBSTANCES ON RUMINAL FERMENTATION PATTERNS IN 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 administra tion of 3 g copper sulphate per animal and day (50 mg copper sulphate per liter rumen fluid) on rumen fermentation patterns have been examin ed. In two series of five incubations each in rumen fluid of five dono rs (total = 50), doses of 2,25 g (37,5 mg/l) and 4,5 g (75 mg/1) coppe r sulphate were simulated. The five donors (517-720 kg) of ruminal flu id 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 c hanges, 3 g appeared to be the limiting dose that reduced the amylolys is (-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 c oncentration of ammonia (+11,2 %; p < 0,001). Therefore 2 g CuSO4/anim al/day is recommended as maximum dose in cattle to overcome Cu-deficie ncy.