Page 23 - MWC 4-21-2022s

Feed Efficiency in Beef Cattle The Midwest Cattleman · April 21, 2022 · P23

By Bob LeValley - Oklahoma BQA Coordinator

Feed is a major cost input gestibility, production of vol-
for all segments of the beef atile fatty acids and methane
production chain. Feed effi- in the rumen, feeding behav-
ciency is always a primary ior, and differences in the mi-
determinant of profitability, crobial population in the di-
but when feed costs are high, gestive tract. Research from
it becomes even more import- Texas showed that steers and
ant. We are most familiar heifers with low RFI had 19%
with feed efficiency being ex- lower feed consumption with
pressed as the amount of feed the same average daily gain.
required per pound of gain, Feed digestibility (along with
or the ratio of Feed:Gain. digestibility of protein and
There is considerable vari- fiber) was increased by 4%
ation in feed intake by in- and ruminal methane pro-
dividuals above and below duction was reduced by 14%
what is expected for the an- in low RFI (or more efficient)
imal’s size and growth rate. cattle. Feeding behavior was
Researchers have been using also tied to RFI.
the concept of “Residual In another study from
Feed Intake” to explore ani- Texas, low RFI steers had
mal feed utilization and the fewer and shorter bunk vis-
efficiency of feed use. Resid- its and meal events, but the
ual Feed Intake or “RFI” is key finding was that low
a measure of feed efficien- RFI steers had less day-to- of Animal and Food Sciences) These findings point to
cy defined as the difference day variation in feed intake. found that while cortisol lev- mechanisms for improved ef-
between an animal’s actual More efficient steers (those els were not associated with ficiency of low RFI calves and
feed intake (either above or with low RFI) have lower feed intake, cattle with high- can provide selection tools to
below) and the expected feed fasting heat production and er cortisol had lower average help beef producers reduce
intake based on the growth thus lower maintenance en- daily gain, higher feed:gain, costs and feed resource use.
rate of the animal. ergy requirements than less and higher RFI (were less ef-
An animal with a pos- efficient steers (those with ficient).
itive RFI would consume high RFI), thus less of the
more feed than expected for feed consumed is used for
a given level of growth, and maintenance.
therefore is less efficient. Stress and disposition
While an animal with a neg- have also been tied to perfor-
ative RFI would consume mance of breeding and grow-
less feed than expected for a ing animals. Cortisol is a
given level of growth and is hormone associated with the
more efficient. Many breed fight or flight response; high-
associations have feed effi- er cortisol levels have been
ciency EPDs based on RFI to measured in animals with
help select for more feed effi- poor disposition (wilder cat-
cient cattle. tle). Research conducted in
Different RFI has been tied Nebraska by Andrew Foote
to differences in nutrient di- (now in our OSU Department