Published online by Cambridge University Press: 27 February 2018
In vitro techniques are widely used to predict the nutritive value of foods for farm animals. However, food evaluation systems are moving towards systems based on nutrient flows rather than on energy or protein. Nutrients are supplied via the digestive tract and presently available in vitro methods are inadequate to simulate the complicated and non-steady-state processes in this tract. This is partly due the lack of adequate in vivo reference values and partly due to a too-high degree of standardization and simplification. Future developments should therefore aim to develop in vitro systems which closely monitor the dynamics of the digestive processes. Adequate interpretation of the results may require sophisticated mathematical models.