Integrating nutrition: a geometrical approach
1999
Raubenheimer, D. | Simpson, S.J.
We present and illustrate using data from insects an integrative approach to modelling animal nutrition. This framework enables the unification within simple geometrical models of several nutritionally relevant measures. These include: the optimal balance and amounts of nutrients required to be ingested and allocated to growth by an animal over a given time period (the intake and growth targets, respectively); the animal's current state in relation to these requirements; available foods and the consequences for the animal's state of ingesting them; the amounts of ingested nutrients that are retained and eliminated; and animal performance. Data are presented on intake targets in insects, illustrating how they change over various time-scales (physiological, developmental, and evolutionary). Most importantly, the geometrical approach enables a clear description to be made of the trade-offs reached by animals in regulating their nutritional balance. Animals given a nutritionally balanced food, or two or more imbalanced but complementary foods, can satisfy their nutrient requirements. However, those eating non-complementary imbalanced foods must reach a suitable compromise between over-ingesting some nutrients and under-ingesting others. Data are presented comparing the rules of compromise for protein and carbohydrate ingestion in grass-feeding (Locusta migratoria) and polyphagous (Schistocerca gregaria) locusts.
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