There's something almost mystical about "doability" in cattle. We all think we know what it is when we see it -- steers that keep gaining during a Panhandle snowstorm, cows that maintain body condition through a Dakota blizzard -- but what really is doability? How is it objectively measured? Can we predict and select for it? Is it economically important?

These are among the questions that brought producers and researchers from across the U.S., Canada and Australia to a Feed Efficiency Symposium in Kansas City recently, sponsored by the National Beef Cattle Evaluation Consortium (NBCEC) -- learn more at www.ansci.cornell.edu/nbcec. NBCEC is an organization of animal breeding researchers at Colorado State University, Cornell University and the University of Georgia whose focus is on genetic evaluation of beef cattle.

"We believe that feed intake measures need to be included in national cattle evaluation," says John Pollak, NBCEC executive director. He says the symposium's goal is to begin to set a national plan, identify existing resources and develop collaborations.

Get 70+ beef producers and researchers in one room and you won't find consensus on too many topics. But everyone agreed doability is related to differences in feed efficiency.

Feed efficiency in growing cattle has traditionally been expressed as the feed-to-gain ratio or feed conversion ratio (FCR). FCR is commonly calculated on pens of growing or finishing cattle (total feed delivered to a pen divided by total gain = FCR).

When individual average daily gain (ADG) is computed within a pen of cattle of known sire groups, FCR for sires can be estimated relatively inexpensively. Individual feed intake is estimated using a regression equation accounting for an estimate of requirements for growth or production and body weight maintenance.

"FCR is a commonly reported, gross measure of feed efficiency, but selection for it is related to increased growth and mature weights, and therefore increased maintenance energy requirements," says Denny Crews, University of Alberta professor in livestock genetics and genomics.

Gordon Carstens, Texas A&M University animal scientist, agrees. "Because FCR is highly correlated with postweaning ADG, yearling weight and mature cow size, it isn't very valuable as a selection tool, but residual feed intake (RFI) is more promising."

RFI (also called net feed intake) is the difference between actual individual feed intake and the intake predicted by the regression equation. RFI data is very expensive to collect (equipment alone costs up to $175/head), but the potential returns may be significant.

RFI is moderately heritable (0.35 to 0.45) and has very low or no correlation to growth, reproduction and carcass traits. According to Carstens, "RFI is not correlated to ADG and is less influenced by compensatory gain."

And Crews says, "When we select for RFI, our range in breeding values covers nearly all the variations. I can still find the full spectrum of frame size and ADG." This allows selection for favorable feed efficiency without affecting other selection criteria important to your management and environment.

Feed-intake studies in Australia began with planned matings in 1992 at the Trangie Agricultural Research Station. The first calves were tested for feed intake in 1994.

Despite the station's location at the edge of the Australian Outback, more than 500 producers attended the first major field day in 1995. Though preliminary and not fully validated, the results "blew them away," says Paul Arthur, director of the Elizabeth Macarthur Agricultural Institute in Camden, New South Wales (Table 1).

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