ESTABLISHMENT OF HYDROGEN-UTILIZING BACTERIA IN THE RUMEN OF THE NEWBORN LAMB

The development of hydrogenotrophic bacteria in the rumen of lambs was investigated by culture and labeling experiments. (CO2)-C-14 and (CO2 )-C-13 incorporation by the rumen microflora of a 24-h-old lamb showed that while there was no labeled methane, double-labeled acetate was f ormed indicating the presence of hydrogen-dependent acetogenesis. In v itro counts from rumen fluid of 20-h-old lambs confirmed an extensive colonization of acetogenic bacteria while methanogens were absent. Met hanogens appeared in the rumen of 30-h-old lambs, and as they develope d there was a proportional decrease in the numbers of acetogens, indic ating a competition for hydrogen between these two groups. Hydrogen-ut ilizing sulfate-reducing bacteria, which were established by the 3rd d ay after birth, did not seem to be affected by this competition.