Author
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Mertens, David |
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Submitted to: Annales de Zootechnie
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/1/1996 Publication Date: N/A Citation: N/A Interpretive Summary: We need to know the amount of food that animals eat in order to properly balance their diets and manage their health and productivity. Numerous equations and computer models have been developed to predict the feed intake of animals, but they are often accurate only under very limited situations of environment and diet. This research attempts to define feed intake regulation by animals as a set of independent mechanisms that control intake during short (within days), intermediate (among days), and long terms (over weeks, months and years). It recognizes that some intake regulation is needed to insure that the animal eats enough food each day to survive. Completely different control processes insure a coordinated response of intake to the demands for growth, reproduction, and lactation during the life of the animal. A conceptual model was developed to describe the complex interactions in a hierarchical system of feedback controls for food intake by animals. This model will serve as a framework for developin a computer program that will more accurately estimate the intake of animals so we can formulate rations that promote better health and productivity in animals. Technical Abstract: Intake of feed by animals is the result of interacting, but independent mechanisms of short, intermediate and long-term feedback control. Long-term homeostatic regulation insures that the animal maintains a stable body energy state for its survival. For survival of the species, homeorhetic mechanisms insure a coordinated response of intake to the demands for growth, reproduction, and lactation. These mechanisms operate via nervous and hormonal controls to match intake with the present and future needs of the animal. Classical theories suggest that energy demand drives intake up to the limits imposed by gut fill. Metabolic comfort associated with the balance of absorbed nutrients or perhaps oxygen utilization efficiency may also provide an upper limit for intake. Long-term intake is the result of integration of multiple feedback signals that may be exclusive (the most limiting signal controls intake) or inclusive (signals interact in some way yto jointly control intake). A conceptual model is described that illustrates the complex interactions inherent in a hierarchical system of feedback controls for intake. |
