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).
|Table 1. Which bull would you rather have?|
|Trait||Bull A||Bull B|
|Start weight (kg)||398||404|
|End weight (kg )||581||569|
|Growth rate (kg/day) (kg)||1.54||1.54|
|Rib fat at start (mm)||4||2|
|Rib fat at end (mm)||14||11|
|Expected feed intake (kg)||1,668||1,639|
|Actual feed intake (kg)||1,585||1,881|
|Feed Conversion Ratio||8.6||10.2|
|Residual Feed Intake (RFI) (kg)||-82.0||+242.0|
|Difference in feed cost = AU$65/head on 120-day test.|
Continue reading on page 2 >
"After the field day, the whole concept took off," Arthur says. "We didn't have a history of central performance testing in Australia, but the producers started to demand it -- before we had reliable data on heritability, etc. So some aspects of the industry moved ahead of the research."
The result was the development of central test stations, and automatic feeders for collecting individual animal intake data. In 1999, a standards manual (www.agric.nsw.gov.au/reader/net-feed-efficiency/nfesm.htm) was first developed with guidelines for testing beef cattle for Net Feed Efficiency to produce certified test records. Based on certified individual animal records from research and industry herds, the first trial estimated breeding values for Net Feed Intake (NFI) were released by Breedplan -- the Australian and international beef cattle performance recording and evaluation scheme -- in 2002 for Angus and Hereford.
Low and high NFI individuals were selectively mated to produce low and high NFI lines of cattle. The results of these selection studies confirm that selection for increasingly different NFI increases the difference between the low and high lines by 0.25 kg/day annually.
There were no differences between the lines in relation to growth traits (birth, weaning and yearling weights), scrotal circumference, pelvic measurement and linear body measurements. Carcass traits (retail beef yield, carcass fat and shear force) also showed no significant differences.
Similarly, maternal and reproductive traits were not different between the low and high NFI lines. Thus, it appears cattle can be selected for low NFI without sacrificing the high-value traits.
Arthur concludes, "The low RFI cows are likely consuming less feed to achieve the same level of productivity as the high RFI cows. At this stage, it looks very promising that selection for RFI works, and has the potential to reduce costs."
Dave Nichols, Iowa seedstock producer and NBCEC advisory council chairman, is supportive: "I think this (feed efficiency) is so critical because we have had a paradigm shift in agriculture" as a result of the growth of the ethanol industry on the demand and price for corn.
"We have a couple of options in the cattle business -- get serious about feed efficiency and management and the use of byproducts, or else have our conventions in about five years with the lobster fishermen because beef will become a special-occasion-only food. Whatever the cost, we as an industry have to address feed efficiency. The biggest cost we have in raising beef is the feed required for maintenance of the cow," he says.
While cow efficiency wasn't addressed in the Kansas City conference, the cost savings for growing cattle are estimated to be substantial. Australian data from 1995 showed a AU$65/head advantage for bulls fed 120 days (Table 1.)
Crews said data on 1,400 Charolais-sired steers in Canada indicated an average feed savings of 390 lbs. between the low and high RFI groups, with no effect on growth, gain or carcass traits.
"This is a big deal," says Scott Moore of King Ranch. "While I can get paid some extra for marketing the right cattle on the right grid, with feed efficiency I get to keep 100% of the improvement."
But not everyone agrees a new emphasis on selection for feed efficiency is warranted. Dorian Garrick, Colorado State University animal scientist, says the often-repeated statement that there's no way to improve efficiency with current EPDs isn't true. He says his work shows focusing on profit rather than biological efficiency using a dollar value index incorporating the current array of EPDs can optimize profit for the producer.
He disputes the contention that the industry must invest in developing an EPD for RFI.
"To me, you want to use all the information you can, not just the little piece that's unexplained by our current predictions (referring to RFI). If we're already doing all the other things right, let's try to fine-tune the last little piece... But, if we're going to invest a huge amount of money on that population to discriminate between differences in RFI, looking at the national industry, there are a whole lot of other activities that will give a much faster and easier return." Those other industry investments, he proposes, should be focused on reproduction, carcass data, animal health and the healthfulness of beef.
Some individual breeders and genetics firms are already working to provide individual feed intake data on yearling bulls. The industry is at a point with feed efficiency similar to when it was searching for good "spread" bulls that would sire low-birthweight calves without sacrificing growth, Nichols says.
"I can't believe for a minute we won't find those outlier bulls, and we've got to get it done," he adds.
-- Bill Zimmerman