Are Rumen Samples Representative of the Diet?

A model of input-content relationships was formulated to examine the effect of turnover time of botanical constituents on their relative abundance in the rumen. For a stable and diverse botanical input the dietary abundance (e) of a constituent (i) was shown to be dependent upon the relative abundance of that constituent in the rumen and the ratio of the turnover time of all constituents (T) to the turnover time of the specified constituent (Ti) (i.e. ei = ri T/Ti). An example of the way in which this equation could be used to correct rumen analyses for the effect of variations in constituent turnover time is given. Validation of the model was precluded by lack of information on the rumen turnover time of individual dietary constituents. A requirement was shown for pertinent information on factors which regulate rumen retention time of individual botanical constituents, particularly for wildlife species in which the diet is heterogeneous.