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Canada’s First Look at Residual Feed Intake EPDs

Canadian Hereford breeders have long believed in the breed’s feed efficiency and now they’re collecting the numbers to back up that claim.

Exceptional breeder participation in the Canadian Hereford Association’s (CHA) residual feed intake (RFI) research project has led to Canada’s first-ever expected progeny differences (EPD) for RFI and a related trait called residual intake and gain (RIG) being published a year earlier than anticipated.

CHA executive director Stephen Scott is calling the results preliminary insofar as the list doesn’t include RFI and RIG EPDs for animals in the final two trials which wrap up this month. Those results will change the ranking, but EPDs for animals already listed won’t change. The current summary includes EPDs for 920 animals, including tested bulls as well as close relatives as long as the accuracies of the relatives’ EPDs are above 10 per cent. By the end of the trials, actual RFI values will have been collected for more than 1,000 horned and polled Hereford bulls tested on the GrowSafe system at Olds College and Cattleland Feedyards in Alberta.

About a year from now, the RFI EPDs for all tested animals and qualifying relatives will change to genomically enhanced EPDs. Researchers at the University of Alberta will be correlating phenotypes (raw RFI results for tested animals) with genotypes (from those animals’ DNA) to do the conversion and ultimately develop a genomic test for RFI.

Reinforcing EPDs with genomic information immediately increases the accuracy of EPDs by adding data equivalent to the actual performance of 10 to 30 offspring (depending on the trait and total number of animals tested in the breed) before a young bull or heifer has even one calf on the ground.

A breed-specific genomic test for RFI will further improve the RFI EPD accuracies without having to put as many offspring from tested animals through the 77-day feeding trial on the GrowSafe system. However, there will always be a need to collect phenotypic data even with genomics to validate that the genomic predictions hold true over time, says Scott, who previously worked with ALTA Genetics when genomics was launched in the dairy industry.

Looking through the summary on the CHA website, keep in mind that low RFI EPDs indicate efficient animals that require less feed than a breed-average animal to put on a pound of gain and that the values are EPDs, not raw RFI data.

EPDs predict the genetic potential of the tested bulls’ progeny; therefore, EPDs for all traits take into account that progeny receive only half their genes from the sire and the heritability of the trait. RFI is considered moderately heritable at about 35 per cent. For example, a bull with an actual RFI of -1.77 had an RFI EPD of -0.714, while a herdmate with an actual RFI of +0.72 had an RFI EPD of +0.134.

The advantage of EPDs is that they remove environmental influence so that Hereford EPDs can be compared across the country, continents and time, Scott explains. Raw RFI values can only be compared for animals fed in the same pen at the same time.

The goal of this part of the RFI project is to find the range of RFI values within the Hereford breed. So far it is -0.830 to +0.997 pounds of dry matter per day (lbs. DM/day) and, because it’s a new EPD, the breed average is 0.0.

“What’s exciting about RFI is that it can be turned into dollars and cents and it’s almost a new trait because it’s independent of other traits,” Scott says. Studies by Dr. John Basarb, research scientist with Alberta Agriculture, and those from the U.S., Ireland and Australia, show that by selecting for RFI, you won’t be selecting for or against other traits such as growth, carcass yield, quality grade, meat traits, cow productivity, hardiness and temperament.

Putting RFI economics into context, Scott refers to the Hereford bulls with the lowest and highest RFI EPDs. Progeny of the bull with the RFI EPD of -0.83 lbs. DM/day should consume that much less than the average animal in the breed to gain the same amount of weight. Progeny from the bull with the RFI EPD of +0.997 lbs. DM/day could be expected to consume almost a pound of dry matter per day more than the average Hereford to gain the same amount of weight. Therefore, calves sired by the efficient bull could be expected to consume 1.83 lbs. DM/day less than calves sired by the inefficient bull, assuming both were mated with average cows.

If the cost of a backgrounding ration is $0.065/lb. DM/day, the difference in feed cost between progeny of the two bulls would be $23.79 per head over a 200-day feeding period.

“Any EPDs added to the many that breed associations already make available need to have economic merit if they are to be embraced by seedstock and commercial cattlemen. As far as commercial application goes, RFI hits the mark,” Scott says.

RIG

RIG EPDs are given as standard deviations from the average for the breed. A RIG EPD with a standard deviation (SD) of 0.0, for example, means the animal is in the top 50 per cent; an SD of 1.0 puts the animal in the top 16 per cent, a 2.0 is in the top 2.3 per cent and a 3.0 is in the top 1.0 per cent for RIG. Conversely, standard deviations of -1.0, -2.0 and -3.0 equate to the 84th, 98th and 100th percentile at the bottom of the rating for the breed.

Scott agrees standard deviations aren’t the most user-friendly way to express RIG and he says this may revert to an index as Hereford associations in Canada, the U.S., Uruguay, and Argentina work toward developing a PACE (Pan American Cattle Evaluation) format for intake-based EPDs. PACE is the program that calculates EPDs for Hereford cattle in all four countries, making it possible to compare Hereford EPDs across these countries. U.S. breeders have already tested approximately 4,000 animals for RFI, while the project is just getting underway in Uruguay and Argentina.

However, RIG is a convenient measure in that a single value can be used to select for animals with higher gains that eat less. On the downside it’s not easily converted into a dollar value and, because it is related to growth traits, there is a possibility that by selecting for RIG a producer could end up double selecting certain growth traits.

RFI selects only for animals that eat less and producers would need to balance that out by selecting for weaning and yearling weight EPDs that fit their breeding program goals.

Breeders weigh in

“It’s a trait that is economically beneficial to all cattlemen — seedstock, commercial cow-calf and feeders — because at the end of the day it’s about producing cattle that will feed better.”

The RFI feeding trials offered a unique chance to go head-to-head with breeders from other parts of Canada. He knew from 16 years of putting bulls on test at the Fort Fraser all-breed bull development centre that Tlell bulls grew well, but had no idea about their feed intake to produce those high gains. No surprise to him, the 20 calves for which he has RFI results to date follow a typical bell curve, with most in the middle, a couple of really good ones and a couple of really poor.

Albert Rimke of AM Ranching shipped bulls to the project from the other side of the Western provinces near Oak Lake, Man. He agrees that finding the RFI range of Hereford cattle is a good project for the breed and and believed it would be important to evaluate bloodlines across the country and within his own herd. In his own herd, he says, the older bloodlines seem to do a bit better.

With RFI results in hand, Doug Mann of Phantom Creek Livestock near Swift Current, Sask., went out to look at calves off their tested bulls and found a few surprises. Some of the most unlikely calves actually had more genetic potential for feed efficiency than he would have guessed.

“That’s the point of testing for RFI, because there’s no way to tell just by looking at the animals, Mann says. “You can gather anecdotal information like easy fleshing or easy keeping, but you need scientific, hard data to really know. The best part of RFI is that it’s unrelated to other traits so you can still select for traits you feel are important to your program and this is an additional tool on top of that.”

Richardson says selecting for RFI could also potentially help turn around traits negatively affected by years of selecting for gain, without hurting growth.

Daniel Doerksen of Gemstone Cattle, at Gem, Alta., believes RFI will end up being a very important tool as far as profitability of herds goes and, in the long view, a valuable piece of the sustainability picture. Basarab’s research shows selecting for RFI can reduce methane emissions by 25 per cent and manure production by 15 per cent.

“This does give us reassurance that what we are doing is working and confidence in RFI as a good management tool,” he says.

Mann plans to use these EPDs to build feed efficiency into his cow herd because that’s where their true savings will be. At the same time he will be mindful that RFI has to be part of a salable genetic mixture because the most feed-efficient bull may not have the eye appeal a buyer wants.

The Rimkes kept a couple of the low-RFI bulls to use in their breeding program and may send sons of those bulls to test for RFI because it will increase the accuracy of their herd sires’ RFI EPDs.

Doerksen says their job now will be to figure out the line where RFI gets too high for an animal to be profitable. They see potential for RFI as a marketing tool and will continue to test new herd sires with the prospect of selling groups of bulls from low-RFI herd sires. Long term, he suspects the development of a cost-effective test for RFI, such as a DNA test, may be the deciding factor in how much it will be used in the future.

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