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Measuring feed efficiency with RFI aids genetic selection

Heather Smith Thomas for Progressive Cattle Published on 23 April 2021
Cattle at the feedbunk

Feed efficiency is highly heritable and can be measured with residual feed intake (RFI). Dr. Randall Raymond, director of research and veterinary services at Simplot Livestock, says most breeders want to make cattle more efficient using less inputs.

“We want maximum production without additional inputs – from a management as well as genetic standpoint.

“At Simplot, we collect feed intake data on all our purebred bulls and heifers and use it to select genetic lines with increased feed efficiency,” he explains.

“We also do RFI testing for seedstock producers who bring bulls to us and test progeny to evaluate sire lines. Since feed intake is heritable and RFI is heritable, we can make progress in feed efficiency when we measure enough cattle, using that data in selection programs.”

RFI is a mathematical calculation that determines how much feed an animal should eat. “If he eats more than that, he has a positive RFI, and if he eats less than that expectation, he has a negative RFI [which is what we want]. It’s a measure of feed efficiency based on what we expect animals to eat for their growth rate,” he says.

“RFI calculation is relative to the group in which those animals were tested. The expected intake is calculated for a peer group, tested at one point in time. Feed intake, when compared across animals in different groups, is not as useful unless we translate it into some type of genetic prediction, such as an [expected progeny difference] EPD,” he says.

“Each breed association has taken a slightly different approach in how to utilize the information. The Angus breed publishes an EPD called residual average daily gain – the inverse of residual feed intake. Herefords have a feed intake EPD, but the Charolais has not yet published an EPD associated with feed intake,” Raymond says.

“Feed intake is correlated to gain, but RFI is a relatively independent trait and not associated with growth. There are some animals that have a very favorable RFI value but very poor gain value.” They don’t eat as much, but they also don’t gain as much.

“We try not to get carried away with any one trait. We evaluate each trait for what it’s worth in our system and select for multiple traits based on how they provide value to the whole system,” he explains.

Some breeders want more feed-efficient females (that do well on forage) and animals that are feed-efficient in the feedlot. “Most seedstock cattle that have been tested are on a moderately high-forage diet, so we could extrapolate that this selection would also make more efficient cows,” says Raymond.

“We’ve made dramatic progress in herds that we’ve aggressively feed tested to find cattle with moderate-to-low feed intake, with appropriate growth rates, but we don’t have enough data. The three maternal breeds we work with – Angus, Red Angus and Herefords – have less than 2% of their respective populations that actually have measured feed intake phenotypes.”

Angus cattle from Licky 7 Angus ranch

Many breeders try to lean more heavily on genetic marker information, thinking that genetic predictions will replace RFI, which is a relatively expensive trait to measure. “In our experience, the accuracy of those predictions fall apart without current phenotype testing for feed intake,” says Raymond.

Charolais in Oregon

One breeder who has been working with Simplot’s system for a long time is Romans Ranches Charolais near Westfall, Oregon. “These progressive producers have been measuring feed intake and recently incorporated DNA into part of that selection system – trying to balance trade-offs of DNA-assisted selection technology and actual measurements. Ideally, we would feed-intake test and DNA test every animal, but there are costs with both technologies, and people have to figure out where to get the most value for the investment,” says Raymond.

Romans Ranches, owned by Bill and Cindy Romans and their son Jeff and his family, runs 800 purebred cows and sells about 250 Charolais bulls annually. “We’ve fed cattle for many years, and feed efficiency is extremely important in a feedlot,” says Bill. “With advances in ultrasound and RFI, we can collect data on individual animals at 12 months of age instead of having to wait for progeny to feed and slaughter. We’ve been feed-efficiency testing our bulls for 11 years.”

At first, all their bulls were sent to Simplot’s facility to test. “Now we just send 40 of our herd sire prospects – four or five good young bulls from each sire group – and DNA on the rest,” he says.

“My goal when we started was to identify the most feed-efficient sires with high gain ability and eliminate the bottom 20 percent. We discovered some lines that were very efficient and some that were not. We’ve learned that feed efficiency is more heritable than previously thought, especially when you breed feed-efficient cows to feed-efficient bulls,” Bill says.

If you can run 20 to 30 more cows on the same amount of feed, or cows maintain body condition on less feed, this helps any rancher’s program. “Our focus is not just to look for the highest RFI cattle. Some of those bloodlines are not the most profitable. Growth is also important. It’s our responsibility as purebred breeders to sell bulls that help move ranchers’ herds in the right direction,” Bill says.

Many top-gaining bulls are big eaters and don’t do well in converting feed. Evaluating efficiency is important. “Bulls that sire calves that are 10 percent more efficient and still gain above average will quickly recover the testing costs. Bulls that sire feed-efficient calves have a substantial influence on the break-even costs of those calves at slaughter and an even bigger influence on a mother cow that eats 10 percent less feed throughout her life,” Bill says.

Angus in Wyoming

Lucky 7 Angus cattle graze

Jim Jensen, Lucky 7 Angus Ranch, has used a GrowSafe system for 13 years. “We were the first Angus producer in the U.S. to invest in this,” he says. The first systems went into universities, but in the past 15 years, there’s been more feed intake testing in commercial environments.

“The way we were running our cows in tough conditions, people who bought our bulls and kept daughters from them were telling us it changed how many cows they could run,” Jensen says. “One customer said he used to run 1,200 cows and can now run 1,800. He used to start feeding hay in early December but now it’s mid-February. The genetics changed after he started using our breeding program.”

Jensen wasn’t looking for feed efficiency; he wanted bulls that would hold up. “Then we realized that if we’d changed the genetics that much just with natural selection and survival of the fittest, without using scientific methods, how much more might we be able to do by using scientific methods to help us locate and propagate the most efficient ones?”

The Lucky 7 Angus herd is now several generations into using feed-efficient bulls. “We can see the difference between what we have today and what we had back then. We have cattle that can do what nutritionists said was impossible,” he says.

These cattle hold body condition with less feed in one of the coldest climates in America and also get by on less forage in summer. “Every year, we put our first-calf heifer pairs in a certain pasture that has X amount of grass and last summer had at least 25 percent extra grass in that pasture. Our genetics made that much difference, after doing this for 25 years. We have more grass left over than we ever had. The heifers and their calves looked the same as ever, but the grass lasts much longer,” Jensen says.

Lucky 7 Angus cattle are watched closely in feed monitor scales for growth

“On one ranch, we run 450 pairs through summer – nearly 50 percent more than we used to. Part of the improvement is due to intense grazing [creating better pasture], but the past few years [we] haven’t done anything different and the number of cows per acre keeps going up.” When feeding in winter, the amount of hay fed keeps going down.

“Some people want smaller-frame cows thinking they are feed efficient, but I tell them frame size has nothing to do with feed efficiency. There are feed-efficient animals in every frame size and breed. We just have to locate them, then choose the phenotypes we want that work on our own place,” he says.  end mark

PHOTO 1: Cattle from Romans Ranches Charolais in Oregon are tested for RFI efficiency at Simplot feedyard in Bruneau, Idaho. Photo courtesy of Romans Ranches Charolais

PHOTO 2: Angus cattle from Lucky 7 Angus ranch in Wyoming have shown greater efficiency through RFI improvements, reducing the need for earlier winter hay feeding.

PHOTO 3: Lucky 7 Angus cattle graze high country in Wyoming

PHOTO 4: Lucky 7 Angus cattle are watched closely in feed monitoring scales for growth. Photos provided by Jim Jensen.

Heather Thomas is a freelance writer based in Idaho.