Consumers have shown considerable interest in “healthy” fats and “bad” fats in recent years. The potential health attributes of conjugated linoleic acid (CLA) and omega-3 fatty acids have led to considerable media focus, consumer confusion, marketing opportunities. Stores have fish, yogurt, eggs and bagels with omega-3 labels. Where is the omega-3 labelled beef? This article summarizes some key research into feeding strategies to increase omega-3s and CLA in beef.
CLAs are natural trans fats that are primarily found in animal products. This is important, because Health Canada has recommended that the trans fat content of prepackaged foods and food service menu items not exceed five per cent of total fat content due to concerns that they may raise cholesterol levels and the risk of cardiovascular disease. However, fresh retail beef and other ruminant products are not included in this recommendation, primarily because transfats are naturally occurring in fresh beef and milk. CLA has been called “the healthy trans fat” because some lab animal studies have shown that CLA may help reduce the risk of cancer, obesity and heart disease, and it might improve immune function, but there is no offi-cial health claim for CLA in Canada.
Omega-3s are a family of at least nine different fatty acids. Omega-3s are found in a very wide range of plant and animal products. Three members of the omega-3 family (ALA, DHA and EPA) have received particular attention. ALA is an essential fatty acid, meaning that it must come from the diet because the body cannot manufacture it. DHA and EPA can either come from the diet, or be manufactured from ALA in the body. ALA is far and away the most abundant omega-3 in beef, and very little of the ALA that a person consumes will be converted to either DHA or EPA. The levels of DHA and EPA are much higher in fish. Products containing omega-3s can have a nutrient content claim, provided the product contains at least 300 mg of omega-3 per serving (75 g of beef in Canada). DHA also has a “biological role” claim in Canada due to its role in brain, eye and nerve development. EPA is believed to improve heart health.
Feeding strategies to increase CLA and omega-3s
The fat from forage-finished beef contains considerably more CLA and omega-3 than grain-finished beef does. But the majority of Canadian consumers trim the external fat from a steak before eating it. This is probably particularly true for consumers likely to seek out CLA or omega-3 products. If the external fat is trimmed, we are left with the marbling fat. Grass-fed beef usually has less marbling fat than grain-finished beef. When CLA and omega-3 levels are calculated on a per-steak basis, the difference between forage-and grain-finished beef virtually vanishes for CLA, although omega-3 levels are still considerably higher in grass-fed than in grain-fed steaks. But remember that a nutrient content claim for omega-3 requires that the beef must contain at least 300 mg of omega-3 per 75 g serving. The total omega-3 content of Canadian beef would have to increase by five to eight times to reach the levels required for a nutrient content claim. Under the Beef Science Cluster, the National Checkoff funds are supporting a study led by Dr. Ira Mandell at the University of Guelph to identify breed and forage combinations that may increase CLA and omega-3 levels in beef.
A second approach has been to feed sunflowers (for CLA) or flaxseed (for omega-3) to increase the dietary supply of the raw materials needed to manufacture these fatty acids in the rumen. A third approach is based on the theory that rumen pH influences fatty acid levels in beef. Due to its lower starch content, DDGS can act as a rumen pH buffer when used to replace grain in the finishing diet. Dr. Mike Dugan and co-workers at the Lacombe Research Station received National Checkoff funds to examine whether adding a pH buffer (1.5 per cent sodium sequicarbonate or distillers grains) to a barley-based diet would affect CLA or omega-3 levels. Although there has been some progress, neither oilseeds nor buffers have successfully increased omega-3 levels enough to reach a nutrient content claim.
A fourth approach has been to feed fishmeal to cattle. This has been more successful in increasing DHA and EPA omega-3 levels in beef. However, feeding even low amounts of fishmeal to cattle can adversely affect the flavour, colour and shelf life of beef. Much of the flavour of meat comes from the fat. A change in the fatty acid composition that negatively affects the eating quality of beef is unlikely to benefit either beef producers or consumers.
Although it has proven difficult to increase omega-3 levels in beef enough to achieve a nutrient content claim, this research has vastly increased our knowledge of the fatty acid composition of beef. This is very important to ensure that the industry has the information that is needed by consumers, food retailers, and regulators.