NATURAL VARIABILITY AND DIURNAL FLUCTUATIONS WITHIN THE BACTERIOPHAGEPOPULATION OF THE RUMEN

To investigate the impact of nutritional and environmental factors on bacteriophage activity in the rumen, it is first valuable to determine the extent of natural variations and fluctuations in phage population s from different animal species, and from animals located together and separately, and variation in animals over time, Differences in phage populations between sheep on different diets, between sheep and goats, and within the rumen over time were investigated by using pulsed-fiel d gel electrophoresis and comparing total phage DNA in ruminal fluid, It was found that no two individuals had similar DNA banding patterns, even when similarly fed and penned together, indicating there is cons iderable individual diversity in phage populations between animals, De spite these individual differences, the;quantities, but not the bandin g patterns, of phage DNA were similar for animals within groups but va ried between groups, suggesting that nutritional factors may influence overall phage activity in the rumen, In sheep fed once daily, a disti nct diurnal variation in the phage population was observed, Two hours postfeeding, total phage DNA dropped to its lowest level, The phage po pulation then increased, reaching a maximal level 8 to 10 h postfeedin g before declining over the next 4 h to reach a stable concentration f or the rest of the cycle, The general trend in phage DNA concentration appeared similar to previously recorded diurnal fluctuations in rumin al bacterial populations in cattle fed once daily.