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Journal of Animal Science Abstract - The Molecular Basis for Feed Efficiency

Physiological basis for residual feed intake1


This article in

  1. Vol. 87 No. 14_suppl, p. E64-E71
    Received: July 26, 2008
    Accepted: Nov 11, 2008
    Published: December 5, 2014

    2 Corresponding author(s):

  1. R. M. Herd*2 and
  2. P. F. Arthur
  1. New South Wales Department of Primary Industries, Beef Industry Centre, Armidale, New South Wales 2351 Australia; and
    Elizabeth Macarthur Agricultural Research Institute, Camden, New South Wales 2570 Australia


Residual feed intake (RFI) is a measure of feed efficiency that is independent of level of production, such as size and growth rate in beef cattle, and thus is a useful new trait for studying the physiological mechanisms underlying variation in feed efficiency. Five major physiological processes are likely to contribute to variation in RFI, these being processes associated with intake of feed, digestion of feed, metabolism (anabolism and catabolism associated with and including variation in body composition), physical activity, and thermoregulation. Studies on Angus steers following divergent selection for RFI estimated that heat production from metabolic processes, body composition, and physical activity explained 73% of the variation in RFI. The proportions of variation in RFI that these processes explain are protein turnover, tissue metabolism and stress (37%); digestibility (10%); heat increment and fermentation (9%); physical activity (9%); body composition (5%); and feeding patterns (2%). Other studies in cattle and studies in poultry similarly found these processes to be important in explaining RFI. The physiological mechanisms identified so far are based on very few studies, some of which have small sample sizes. The genomic basis to variation in these physiological processes remains to be determined. Early studies have shown many hundred genes to be associated with differences in RFI, perhaps in hindsight not surprising given the diversity of physiological processes involved. Further research is required to better understand the mechanisms responsible for the variation in RFI in target populations and to marry the physiological information with molecular genetics information that will become the basis for commercial tests for genetically superior animals.

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