Feeding is vital for animal growth and the maintenance of health. However, the underlying mechanisms that mediate dietary performance have long been a so-called black box. It is only during recent years that studies have demonstrated that nutrients act as signals that can be sensed by cells and organisms and that play vital roles in gene expression and metabolism. Multiple signaling pathways have been identified as being responsible for the sensing of discrete nutrients. While successes have been achieved in the exploitation of nutrient-sensing signals in drug discovery and disease control, applications based on the sensing and metabolic control of major nutrients (proteins, lipids, carbohydrates, etc.) in aquaculture and land-farmed animals remain in their infancy. We thus provide a tentative perspective on future research topics and applications of nutrient sensing in animal nutrition.