Nutritional Control of Feed Intake in Dairy Cattle

Feed intake is determined by many interacting factors and prediction of feed intake is the “Achilles heel” of diet formulation. Many different diet characteristics interact with environment and physiological state of cows, making it difficult to predict feed intake accurately. However, understanding the factors controlling feeding allows us to manipulate diets to optimize feed intake. Eating is controlled by the integration of peripheral signals in brain feeding centers. Dairy cow diets must contain a minimal concentration of relatively low-energy roughages for proper rumen function and signals from ruminal distension can control feed intake when the drive to eat is high and metabolic control of feed intake is diminished (e.g. cows at peak lactation). Signals derived from metabolism of fuels dominate the control of feed intake when signals from distension diminish (e.g. cows in late lactation). Therefore, effects of diet on feed intake vary with the physiological state of the animal. Furthermore, they interact with environmental stressors such as social (e.g. overcrowding) and thermal stress. The objective of this article is to discuss factors controlling feed intake in lactating cows and how they can be manipulated to optimize feed intake. “Optimal” feed intake might mean the maximum to attain higher milk yields for high-producing cows or less than maximum to increase efficiency of feed conversion for lower producing cows.