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Feeding Flax
by
Heather Smith Thomas |
Flaxseed and flaxseed oil added to feedlot cattle rations can
improve carcass quality, according to research directed by Jim
Drouillard, PhD, Professor of Beef Cattle Nutrition and Management,
Department of Animal Sciences and Industry, Kansas State U.
The first studies looked at flax as a way to enhance immune
response and limit affects of inflammation in respiratory disease;
beneficial affects on carcass were discovered by accident.
“When we fed flax to stressed feeder calves, we fed it for only the
first 5 or 6 weeks of their feeding period. We happened to keep many of
those animals in their original groups, and then they were put in a
finishing program. We were able to monitor their performance, and more
importantly, their carcass characteristics at slaughter. We found that
the animals that had received flaxseed or flaxseed oil appeared to have
better carcass quality,” says Drouillard.
About 180 to 220 days after having flax in their ration, there was
a large residual effect on marbling and quality grade.
“If we started with a base line of 33 percent Choice or better, it
might boost it up to 44 percent. In another case we started with a base
line of 67 percent (on cattle fed tallow or no fat at all, with
comparable levels of quality grade), but when we fed flax this jumped to
82 percent. When we fed flax oil, it jumped to 94 percent Choice or
better (and 39.8 percent were actually Prime).
“Unfortunately, the oil is not readily available. Linseed meal (the
protein meal remaining after extraction of oil from flax seed) is not a
good source, because it has a very low level of oil left in it. So we
buy commodity flaxseed, grind it, and add it to feed. That material is
about 40 percent fat. We typically add between 5 and 15 percent fat to
the diet this way; most of our work with flax has been at about 10
percent of the diet,” he says.
One of the graduate students compared flax to feeding tallow, and
to no added fat, and observed improvement in quality grade in the cattle
fed flax.
“In this experiment, flax was fed to yearling steers the last 80
days before slaughter. We did some analysis of blood, and found a high
concentration of alpha-linolenic acid. We analyzed muscle tissue and
also found high concentrations of alpha- linolenic acid. This was
exciting, because alpha-linolenic acid is among the omega-3 class of
fatty acids and there are a number of human health benefits linked to
these,” says Drouillard.
ENHANCING THE
“GOOD FATS” IN BEEF
“Our focus the past several years has been on the finishing animal,
looking at carcass quality effects, and at the potential for enrichment
of carcasses with omega-3 fats,” he says.
When feeding flax to cattle for 70 to 120 days before slaughter,
the omega-3 fats are deposited into the muscle tissues; you get about a
ten-fold increase in omega-3 fats.
“Most of that increase comes in the form of alpha-linolenic
acid. We do, however, get some increase in EPA (ecosapentanoic acid)
which is one of the fatty acids associated with certain types of marine
fish that are supposedly good for our health because of the long chain
omega-3 oils,” he explains.
“One of the things we encountered early on however was that it
seemed to create an off flavor--like a mild degree of rancidity. We know
that linolenic acid is more easily oxidized than other fatty acids, so
we felt we needed to resolve this problem, or there would be little
point in feeding flax. We experimented with adding vitamin E to the
ration as an anti-oxidant, and eliminated the off- flavor problems. It
may even increase the absorption of vitamin E a little, just by having
flax in the diet.”
That’s probably true with any fat added to diet, since vitamin E is
a fat soluble vitamin, he says. “Subsequently, in all the work we’ve
done with flax, we add about 1000 units or more of vitamin E per day in
each animal’s diet.
CURRENT RESEARCH
“Since that time, we’ve had a number of studies with flax and have
almost always seen an increase in quality grade, with a couple
exceptions. In one instance we fed flax to yearling animals at a rate of
10 percent of the diet. The cattle graded in a range of 65 to 67 percent
Choice. We did not see an improvement in quality grade, but saw marked
reduction in yield grade. It was a large impact. So there still seemed
to be some repartitioning of the fat, to where we maintained marbling
but greatly reduced the subcutaneous fat, kidney/pelvic fat, etc.” says Drouillard.
“In cattle that were not fed flax, we started with 12 or 14 percent
yield grade 4’s. When we fed flax, we virtually eliminated yield grade
4’s and picked up a lot of additional yield grade 1 and 2 type
carcasses. We don’t understand why that happens, but we’ve seen this a
couple of times--where flax is administered later in the feeding period.
It usually manifests as an increase in quality grade, and on occasion
has made no change in quality grade but a significant improvement in
yield grade. It depends on what the choice/select spread is, and what
kind of discount you get for yield grade 4’s and 5’s, but in many cases
we’ve seen an increase in value ranging from $10 to more than $20 per
head,” he says.
“Since many feedlots are not equipped with hammermills or
rollermills, we want to determine if it would be possible to derive
these benefits by feeding flax in unprocessed form. Flax is a very small
seed and we assumed you need to grind it or break it in order to
facilitate digestion. We need to know if we can feed flax in unprocessed
form and still derive some benefit. We’ve started a project on that,”
says Drouillard.
“We’re also engaged in larger scale studies at the feedlot level,
trying to understand more about when flax should be fed in order to
derive the greatest benefit, in terms of carcass quality improvements as
well as carcass enrichment with the omega-3 fats.”
“These studies have opened our eyes. For years we thought fat was
fat. We’ve discovered that fats are not all the same. It’s not just a
source of energy; there are some biologically important properties of
fats that we failed to consider in the past. We are learning that flax
and some of the other fats may have some important repartioning
effects,” he says. |
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