Animals that eat less than required for growth have a negative residual feed intake
OLDS, Alta. — Two bull calves standing in a pasture may look the same, but one could be more feed efficient than the other.
That trait is an economic benefit to the cattle industry because feed costs are the largest expense in raising beef.
Bulls that eat less but gain the same are considered more efficient and therefore more valuable be-cause the odds of them passing on that trait to progeny is high.
“From the top bulls to the bottom bulls, the difference in feed costs would be $40,” said Stephen Scott, manager of the Canadian Hereford Association.
That is the premise of a Hereford association project, which for the last three years has tested 1,000 bulls at Olds College and Cattleland Feedyards at Strathmore, Alta., for residual feed intake and feed efficiency. DNA samples were collected and individual feed consumption was measured to come up with statistics for residual feed intake.
Residual feed intake is the difference between an animal’s actual feed consumed and its calculated feed requirements based on body weight and average daily gain during a standardized test period.
Efficient animals eat less than expected for maintenance and growth and have a negative or low residual feed intake, while inefficient animals eat more than expected and have a positive or high residual feed intake.
The trial finished at the end of March, but the association has already applied for more funding to continue.
Breeders have traditionally concentrated on selecting fast growing bulls that gained well, but the new data may change that emphasis into something more useful, Alberta Agriculture researcher Susan Markus said at a rancher’s day at Olds College last month.
“What we have been doing over the last 50 years in the beef industry is basically getting cattle that grew larger and grew faster and cost us more money because we were chasing mostly the trait of average daily gain,” she said.
“When you chase the trait of average daily gain, you are going to get larger animals. By putting feed efficiency in there to get that gain, we are able to scale back a bit on the size of the cattle.”
Finding more efficient animals does not mean turning back the clock to producing smaller cattle.
“I can tell you RFI is not about size. We do not have to have smaller cattle to have more efficient cattle,” she said.
“RFI is measuring metabolic efficiency. It is like a golf score: the more negative, the better the number.”
The residual feed intake number is an average of zero when reading a bull’s statistics. Those with a positive number are less feed efficient than those with a negative number.
This information should not be used for single trait selection be-cause there are other traits with equal value, such as calving ease, fertility, longevity and age at puberty.
However, it appears good residual feed intake numbers do not negatively affect other valuable qualities.
“There is no correlation to show we are moving in the wrong direction,” she said.
The Hereford association plans to develop genomically enhanced expected progeny differences so breeders can select bulls with that trait as well as other economically valuable qualities, such as carcass quality, said Scott.
The association also wants to start collecting carcass data so information on the high yielding and top grading animals can be correlated with their sires.
“If we can have a central database that truly works and identifies the parentage of an animal and its carcass grade and yield grade, then we can use that data to give back to breeders so they can make better breeding decisions,” said Scott.
“That truly will resonate through the population if those selections are made. If we don’t get the data back, it is not possible to make those sorts of changes in the industry.”
There is also an ambitious plan to release information that can help select females that are highly productive and have greater longevity.
He said more DNA tests will be used to select females and decide which bulls to breed them to as they become cheaper.