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The essential role of EFAs

Elliot Block Published on 07 October 2009
Essential fatty acids (EFAs) continue to be a hot topic in dairy cattle nutrition as new research, on-farm trials and meetings provide additional information to the industry on how critical EFAs are for the dairy cow.

Not only are we continually learning more about the roles of EFAs in reproduction, but new research currently underway may tell us how EFAs can impact each stage of the cow’s lifecycle.

There are five key reasons why EFAs are important and why they should be included in the dairy cow ration, says Dr. Charles Staples, professor of animal science at the University of Florida.

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Cows do not produce EFAs naturally.
Fatty acids are the individual unit of measure for lipids and each has a distinct structure and function that influences the dairy cow’s metabolism, shares Staples. EFAs – including Omega-3 (linolenic acid) and Omega-6 (linoleic acid) EFAs – cannot be produced by the cow using other available nutrients or chemical pathways. The only way EFAs can be supplied to the cow is through the diet.

Rumen microbes transform EFAs.
In many instances diets may supply adequate amounts of linoleic acid to the cow, but rumen microbes convert much of it to stearic acid or saturated fats, explains Staples. Feed sources like cottonseed and soybeans are often used to help meet EFA needs, but once in the rumen, many are biohydrogenated and are no longer EFAs. By feeding a rumen bypass source of both Omega-3 and Omega-6, you can deliver these two EFAs in a consistent form.

Cows secrete EFAs everyday.
Cows lose EFAs each day through milk production, confirms Staples. A cow producing 100 pounds of milk per day secretes about 0.11 pounds – or 50 grams – of linoleic acid per day in the milk. The amount lost represents most of the Omega-6 that is absorbed from feedstuffs, so additional EFA supplementation can meet further daily maintenance and reproductive needs.

EFAs influence every step of reproduction.
Staples notes that research confirms that supplementation with EFA can improve reproductive performance.

This is possible because EFAs serve three specific functions to facilitate reproduction:
• Aid in the production of specific reproductive hormones, especially progesterone, possibly through improved growth of ovarian follicles and larger corpus lutea. Higher concentrations of progesterone result in stronger heat signs and improved heat detection, conception rates and pregnancy maintenance.
• Aid in the production of prostaglandins (eicosanoids). These help establish new estrous cycles. In addition, they enhance visible signs of heat and increase blood flow to the ovaries.
• Promote integrity of the cow’s cell walls. Research at the University of Arizona reported the effectiveness of EFA supplementation in improving reproductive performance and health.

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The trial was completed on a 2,000-cow commercial dairy and focused on reproductive performance in cows fed Omega-3 and Omega-6 EFAs. The study showed more cows got pregnant sooner when fed EFAs versus cows not supplemented with EFA.

Additional study highlights include:
• 81 percent more ovulations by 30 days in milk
• 38 percent more estrous cycles in the first 60 days in milk
• 25 percent fewer uterine health disorders
• Fewer postcalving disorders, DAs, milk fevers and abortions

EFAs are critical for heifers too.
Research on EFAs began in the 1920s where growing rats were fed fat to determine which fatty acids were essential for growth and health. The study identified both Omega-3 and Omega-6 as the key EFAs to maintain growth and health in the population.

Almost 30 years later – in 1954 – researchers completed a heifer trial to identify calves’ requirements. The researchers concluded that calves fed a fat-free diet were nutritionally deficient and showed symptoms like depressed growth, scaly dandruff, hair loss and diarrhea.

Today, calf diets provide low levels of linoleic acid, while research is confirming the need for additional supplementation. In a recent trial, heifers fed a diet with 0.25 percent EFA supplementation gained an additional 0.16 pounds per day over the nonsupplemented group.

Researchers concluded that the cost of supplementing heifers over the 84-day trial – a mere $0.46 for the whole 12-week period – was minimal compared to the growth benefits seen. Because dietary requirements have not been clearly identified it’s hard to know if animals are deficient in EFAs, and what proper supplementation may mean to performance and health.

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Staples notes that future research will continue to provide insight on the role EFAs play and the feeding amounts that can ensure calves, heifers and cows are receiving their daily needs to meet growth, production and health potential.

As more research and information becomes available on EFAs, it will continue to revolutionize how we feed the dairy cow. To this point EFAs have been confirmed to improve herd performance and health, and continued research and on-farm trials will bring the industry closer to identifying recommended feeding amounts. PD

References omitted but are available upon request at

Elliot Block
ARM & HAMMER Animal Nutrition

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