Flax in Egg Production
The Omega-3 Connection
The major component of flax, alpha-linolenic acid (ALA), heads the omega-3 fatty acid family. The omega-3 fatty acids, and particularly ALA, are recognized contributors to good health in infants and adults.
ALA is receiving special attention for its role in heart health. Consumption of omega-3 fatty acids from eggs has been reported to reduce blood pressure and serum triglycerides in humans. Researchers have also noted those omega-3 fatty acids decrease platelet activity. (Aggregating platelets contribute to plaque formation in arteries which can lead to coronary artery disease.) In fact, researchers have reported that consuming as little as 800 mg of omega-3 fatty acids from eggs per week significantly reduced platelet aggregation in a human study group.
Omega-3 enriched eggs have an important role to play in the diets of consumers and can lead to the prevention of disease. In addition to increasing the ALA content of the diet, some of the ALA elongates in the body into two other omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Therefore, one omega-3 enriched egg provides nearly half of the optimal intake level of ALA, and about one-quarter of the optimal intake level of EPA and DHA.
At present, levels of omega-3 fatty acids in the modern human diet are historically low in comparison to those of omega-6 fatty acids. Nutrition experts, including Health Canada, recommend an increase in the intake of ALA to 0.5% of total energy.
Why Add Flax to Laying Hen Rations?
People are paying close attention to the foods they eat, modifying their diets to maintain good health. The fat content of the diet is of particular interest to those concerned about heart disease. Health-conscious consumers are looking for food products which contain the important omega-3 fatty acids, and especially alpha-linolenic acid (ALA) in which flax is so rich.
The fat composition of flax is unique. It contains a very high content of polyunsaturated fat, and 57% ALA.
Including flax in the rations of the laying hen alters the fatty acid composition of the egg yolk, increasing its omega-3 fatty acid content. The resulting enriched eggs provide a convenient way for people to improve their omega-3 intake and achieve better health.
Using flax as 10 or 20% of a poultry ration can increase the ALA content of egg yolk fat from 0.4% in the ordinary egg to 4.6% and 8.9%, respectively.
What Is the Effect of Flax Rations on Yolk Fatty Acids?
When feeding milled flax to laying hens, alpha-linolenic acid (ALA) in the yolk increases proportionately with increasing dietary inclusion. For example, feeding 5% milled flax yields approximately 8.5 mg/g yolk ALA, 10% yields an average of 16.3 mg/g of yolk, 15% provides about 19 mg/g yolk, and 20% has been reported to provide 30 mg/g of yolk. Accordingly, researchers have reported amounts of ALA as 5.8 and 8.8% of total yolk fatty acids following feeding of 8 or 16% full-fat flax, respectively.
Studies also show an increase in yolk docosahexaenoic acid (DHA) following flax supplementation. Several studies have reported DHA yolk content from flax in rations to range between 5-7 mg/g of yolk.
Flax Laying-Hen Rations
Length of feeding time
The incorporation of alpha-linolenic acid (ALA) into egg yolk from flax-enriched rations is a gradual process, occurring over several weeks. Researchers have determined egg-yolk fatty acids after 14, 90, and 180 days. Consistent yolk ALA was obtained between 14 and 90 days of feeding. Scientists have reported that yolk ALA, eicosapentaenoic acid (EPA), and docosahexaenoic (DHA) contents stabilized after four weeks of feeding.
Importantly, once the desired yolk omega-3 fatty acid contents are obtained, the dietary supply of omega-3 fatty acid must remain consistent. Researchers reported a 20% reduction in yolk ALA following just one a week of feeding an omega-3 fatty acid-free-ration to previously supplemented hens.
Addition of vitamin E
Researchers have reported a 2% increase in hen/day egg production when hens fed either typical or omega-3 fatty-acid-rich rations were further supplemented with 50 IU of vitamin E per kg diet. Researchers have reported that excess dietary vitamin E is deposited in egg yolk such that yolks may contain up to eight times the content normally found in an egg. This excess yolk vitamin E could further enhance the nutritional quality of omega-3 fatty acid- rich eggs. The flavour quality of vitamin E/omega-3 fatty acids enriched eggs may also be superior to eggs solely containing enhanced omega-3 fatty acids.
Current practice in feed formulation is to stabilize flax with the addition of a tocopherol/ Vitamin E antioxidant at the level of 10 mg/100g of feed.
The opportunity for economic gain from the production of omega-3 fatty acid enriched eggs is significant. As omega-3 enriched eggs offer a taste and quality similar to regular eggs, but with enhanced nutrition, this segment of the egg market should continue to grow. At present, in Canada, omega-3 enriched eggs account for about 15% of the shell egg market.
In a consumer survey conducted in Texas in 1994, more than half of those surveyed suggested a willingness to pay more per dozen for these nutritionally enhanced eggs. As consumers become more informed about the health benefits of omega-3 fatty acids, the popularity of the enriched eggs will become more widespread.