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Twenty antibacterial agents were evaluated as to their effectivity in inhibiting microbially-mediated ruminal biotransformation of the alkaloid jacobine in ewes. Rifampicin and erythromycin were found to inhibit the process at concentrations as low as 1 microgram/mL or less. Other antimicrobials were deemed only slightly less effective. Agents active against gram-positive bacteria were the most efficient in preventing biotransformation, hence these microbes are postulated to be the most important organisms in this process.

The nutritional and temperature requirements for extracellular polysaccharide (EP) production by Butyrivibrio fibrisolvens nix was determined. Strain nyx was grown anaerobically using different carbon and nitrogen sources. Results showed that EP poduction was similar at temperatures 35-40 degrees C. In addition, glucose was found to be the most efficient carbon source resulting in the fastest growth and highest EP production. The different nitrogen sources supported the same rates of growth and EP production. The resuls also showed that EP production was exponential during exponential growth but no EP was produced during the lar or stationary phases.