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Adding Linseed to Feed
enhAnces the FAt
ProFiLe oF BeeF
summary
Feeding beef cattle a ration containing whole flax seeds
(linseeds), flax (linseed) oil, rolled linseed or milled linseed
increases the alpha-linolenic acid (ALA) and conjugated
linoleic acid (CLA) content and decreases the omega-6/
omega-3 ratio, but has little effect on the saturated fat content
of beef. Adding linseed to feedlot diets has been shown to
increase the internal fat of heifers and the U.S. Department
of Agriculture yield grades. These enhancements to the fat
profile of beef give consumers value-added foods with
acceptable sensory qualities and a healthy fat profile.
introduction
Food processors continue to think of innovative ways of
adding flax to their food products. Consumers now enjoy
traditional and hearth breads, muffins, bagels and cereals,
as well as energy bars, pizza, smoothies and meatless vegan
meals, all made with added flax.
1
On the livestock side,
primary producers add flax (often referred to as linseed) to
livestock rations, the aim being to increase the content of
healthy fats in eggs, meat, poultry and dairy products, thus
making additional omega-3–enriched foods available for
health-conscious consumers.
Adding linseed to the rations of steers improves the fat
profile of beef. Most research in ruminant nutrition in North
America has been undertaken on cattle, although studies have
also shown beneficial effects of linseed on the fat profile of
lamb meat.
2
the
challenge of
changing the
Fatty Acid Profile of Beef
The fact that ruminants digest their food in stages presents
challenges for cattle producers, the main one being the
process of biohydrogenation – the chemical reactions
whereby microorganisms in the rumen transform the
polyunsaturated fatty acids found in animal feed into saturated
fatty acids. Ingested feed first enters the rumen, a digestive
compartment that works much like a fermentation vat
(see box page 2). The ingested dietary fats undergo many
chemical changes carried out by bacteria, protozoa and
fungi.
4
However, rumen bacteria cannot break down dietary
fatty acids. To enrich beef with polyunsaturated fatty acids
like alpha-linolenic acid (ALA), the essential omega-3 fatty
acid, and its long-chain metabolites, eicosapentaenoic acid
(EPA), docosapentaenoic acid (DPA) and docosahexaenoic
acid (DHA), the dietary supply of these fatty acids must be
protected from rumen biohydrogenation. Various methods of
interfering with the bacterial metabolism of long-chain fatty
acids in cattle and sheep have been tried, including the
following:
4
• Feeding
whole linseeds with their seed coat intact to slow
the release of fatty acids in the rumen and protect against
their oxidation;
5
and
• Protecting
seeds by encapsulating
them in formaldehyde-
treated protein.
