CONVERTING THE HERD ...
TO RFI EFFICIENT ANIMALS
by Bruce Derksen
I
t was a proud moment for Limousin breeder Wulf Cattle of Morris,
Minnesota, when their bull, Wulfs Xcellsior X252X, topped the
2020 list of GrowSafe Systems 150 proven bulls for Residual Feed
Intake (RFI). In total, the North American Limousin Foundation
(NALF) placed 11 bulls on the list with three in the top 10. While
many purebred breeders sat up to take notice, some of their fellow
seedstock producers, and a large percentage of commercial cattlemen,
raised an eyebrow and questioned what this really meant.
Definition and Importance
RFI has been around for a long time but is often an ignored or
misunderstood factor in determining cattle efficiency. Most cattlemen
rate their animals on feed to gain or feed conversion ratios and in
a pen setting, this can give a good indication of how efficient one
group of cattle is in relation to another. But for cow-calf producers
attempting to strengthen their herd through genetic selection, this
can be less meaningful and even less useful.
RFI is calculated by subtracting the expected feed requirements
for maintenance and growth from the actual intake of an individual
animal, resulting in a low or negative number being the most efficient
animals. Systems such as GrowSafe track feed and water intake
through a computerized process over a period of at least 70 days and
calculate actual individual consumption and weight gain. Efficient
(negative or low RFI) animals use less feed for a high average daily
gain. Inefficient (positive or high RFI) animals consume a larger
amount to match the same gain.
Dr. Gordon Carstens, Professor of Animal Nutrition at Texas A&M
University, says it is important to identify cattle that are superior
when it comes to converting feed to pounds of meat. These costs
can represent more than 70% of total production costs to cow-calf
producers thus any opportunities for reduction can provide benefits
to an operation’s bottom line.
“Real cost savings go back to feed cost savings, but mature cow sizes
have become larger. A rancher with a definitive grazing acreage who
stocked one cow per five acres 20 years ago, is likely still stocking the
same today. Yet those females might be 10-15% heavier, so the actual
cow numbers on those acres should have been reduced.”
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Feed costs can represent more than 70% of total production costs to
cow-calf producers thus any opportunities for reduction can provide
benefits to an operation’s bottom line. It is important to identify cattle
that are superior when it comes to converting feed to pounds of meat.
Studies have also shown low RFI heifers remain consistent as mature
animals. “There is a favorable association between the efficiency of the
growing animal and the cow,” said Carstens. “It’s not an automatic
when we select for a particular trait in a growing animal that it
translates into genetic merit in a mature female.”
He described an A&M trial that measured RFI in heifers and again
as 2- and 3-year-olds, using an electronic feed intake system. Results
showed the low RFI heifers matured into low RFI cows.
Trials and Savings
Feedlot tests routinely show an improvement in conversion rates
of 9-15% in identified low RFI cattle with extreme cases as high as
25%. Since the trait transfers to the adult, populating the average
commercial herd with low RFI females can have an astounding effect
on costs.
Groups of cattle will normally exhibit a 40% range in efficiency.
Low RFI females in the herd will be 20% more efficient than the
average. A hypothetical 50 cow herd comprised of low RFI animals
would consume 20% less hay or forage to maintain the desired health
and condition in comparison to an unselected 50 cow herd. Assuming
a 1,200-pound cow eating 24 pounds of hay per day, a 20% reduction
delivers a 4.8 pounds/day saving. All 50 animals eating 4.8 pounds
• APRIL 2020
continued on page 36