A computational framework for a nutrient flow representation of energy utilization by growing monogastric animals

TLDR

The study presents a computational framework to model nutrient utilization for protein and lipid accretion in growing monogastric animals. The framework explicitly models nutrient and metabolite flows, biochemical transformations, and five calibration parameters that adjust the marginal input–output response for a species, providing a detailed computational representation of energy requirements for intake, excretion, and accretion. The model improves prediction of energetic efficiency of nutrient intake and can generate mechanistically predicted net energy values for diets at specific metabolic states.

Abstract

A computational framework to represent nutrient utilization for body protein and lipid accretion by growing monogastric animals is presented. Nutrient and metabolite flows, and the biochemical and biological processes which transform these, are explicitly represented. A minimal set of calibration parameters is determined to provide five degrees of freedom in the adjustment of the marginal input–output response of this nutritional process model for a particular (monogastric) animal species. These parameters reflect the energy requirements to support the main biological processes: nutrient intake, faecal and urinary excretion, and production in terms of protein and lipid accretion. Complete computational details are developed and presented for these five nutritional processes, as well as a representation of the main biochemical transformations in the metabolic processing of nutrient intake. Absolute model response is determined as the residual nutrient requirements for basal processes. This model can be used to improve the accuracy of predicting the energetic efficiency of utilizing nutrient intake, as this is affected by independent diet and metabolic effects. Model outputs may be used to generate mechanistically predicted values for the net energy of a diet at particular defined metabolic states.