Research uncovers a novel way of measuring feed consumption on pastures

“We’re really focused on DMI (dry matter intake) as a way to calculate RFI, an efficiency metric for an animal so that people can make selection decisions.” In fact, said Nathan Blake, speaking at the 2024 annual convention of the American Wagyu Association, residual feed intake or RFI is his favorite efficiency measure.
That’s because RFI is helpful in several ways. It’s moderately heritable, at 0.35 to 0.4. And RFI is independent of other traits, so a beef producer can select for more feed-efficient animals without worrying about affecting other traits, like marbling.
But measuring DMI is fundamental in determining RFI, Blake said. However, while calculating feed intake in a drylot is relatively easy, doing so in a pasture setting in the past has been very difficult.
Enter Blake’s Ph.D. research at West Virginia University and a remarkable scientific twist.
In measuring feed intake in a drylot, Blake found the variable most important in predicting dry matter intake is daily water consumption. “We were able to predict individual dry matter intake by within about a kilogram for animals in a drylot setting,” he said.
Beyond water intake, the other important variables in predicting feed consumption were body weight and age. “It’s been known for a long time that body weight and age are strong predictors of DMI — nearly all of the published equations incorporate these features to some degree,” he said.
“However, measuring individual water intake is a very recent advancement that allows us to assess previously inaccessible relationships among intake variables and animal performance. Additionally, body weight and age alone do a good job of predicting DMI on the average. However, when seeking anomalous animals — efficient or inefficient — it’s critical to predict DMI accurately in all cases, not just on the average.”

FREE RANGE

But what about animals free ranging on pasture? To overcome that obstacle, Blake’s team developed a portable machine that measures body weight and water intake. The result? He was able to predict dry matter intake by animals on pasture to less than a kilogram.
While water and dry matter intake was relatively consistent between breeds, Blake found that Wagyu cattle visited the water trough more times during the day than other breeds.
The bottom line, he said, is identifying animals that are really efficient so those traits can be selected for, or animals that are inefficient so they can be culled. “And we’re able to predict those animals pretty well.”
While that’s important regardless of breed, it’s even more important for Wagyu breeders because of the longer feeding period. “Selecting for efficiency is going to have a much greater impact on the cost of having those animals around,” he told Wagyu breeders.
For example, he talked about a pair of bulls from the same operation that were consigned to West Virginia’s bull test a few years back. “They had the same sire, they were bred to half-sister cows, they were born one day apart, they were fed the same ration for the performance test and they had nearly identical performance at 4.2 pounds per day.”
However, the inefficient bull consumed 1,500 more pounds over the 70-day test than its efficient half-brother. Over a year’s time, the inefficient bull would have consumed an additional 7,200 pounds of feed, Blake told Wagyu breeders. The bulls’ breeder told the team that looking at phenotype, he would have selected the inefficient bull.
Cattle are complicated animals and a number of additional variables can affect any given performance trait — rumen microbiome, additional environmental factors like heat and humidity, and for Wagyu, less genetic variation than other breeds.
But an accurate measure of feed efficiency can be an important factor in profit potential. To that end, Blake and his team are cooperating with several other universities in using the mobile water intake machine in research.
Beyond that, because Blake’s research was conducted in small paddocks, he’s interested in collaborating with cattle producers in developing data from on-the-ground research on farms and ranches. “If you run a large operation and would be interested in having one of these mobile units, please send me an email at neb00001@mix.wvu.edu.”
There’s a wait list for machines at the moment, he said, but they’re working to overcome that. “We’ll work on getting more machines in about a year. We’d love to collaborate.”