Manipulation of gastrointestinal nutrient delivery in livestock.

Discussed herein are the constraints of nutrient delivery from the gastrointestinal tract that are placed on postabsorptive synthetic processes in highly selected strains of domestic livestock or livestock treated with growth promotants exogenously or via transgenic manipulation. Emphasis is placed on the discussion of recent advances in the knowledge of the regulation and manipulation of digestion and the absorption by the intestinal epithelium. Slaframine, a muscarinic exocrine secretagogue with a high affinity for the gastrointestinal tract, and epidermal growth factor may have practical potential for the manipulation of digestion and absorption, respectively. Special consideration is given to energetic considerations that must accompany any manipulation of gastrointestinal function. Down-regulation and up-regulation of mechanisms must be equally considered as this area is explored further.