Method for calculating digesta flow and apparent absorption of nutrients from nonrepresentative samples of digesta

A mathematical method is presented for measuring net disappearance of nutrients as digesta traverses the digestive tract of animals equipped with simple cannulae. The method requires that each distinct phase of a sample be physically separated if this phase forms a different percentage of the sample than it does of the total digesta. In addition, the number of dietary markers used must equal the number of phases separated. Each marker is administered continuously and simultaneously. It is not required that markers associate completely with one phase. Transfer ("hopping") of markers among phases does not invalidate calculations provided that such transfer does not cause complete randomization. The solution is presented in matrix form to be adaptable to any number of digesta phases.