by-Dr.Surendra Khanna, Poultry consultant, Chandigarh &
DR. RAJESH KUMAR SINGH, JAMSHEDPUR
• The contents of the chicken egg can be changed in such ways as to be more healthful and appealing to a segment of our consumers who are willing to pay for those changes in the egg.
• “Designer eggs” are those in which the content has been modified from the standard egg.
• Designer eggs are produced by feeding egg-laying hens with a special diet rich in certain vitamins and other nutrients.
• The special diet usually includes kelp, flax seeds, canola oil and marigold extract.
VITAMIN ENRICHMENT
• Designer eggs have been produced that contain higher concentrations of several vitamins, especially vitamins, A and E.
• The vitamin content of the egg is dependent on the dietary concentration of any specific vitamin to some extent. The efficiency of transfer of different vitamins into the egg varies with different vitamins.
• Vitamin transfer efficiency and cost of the vitamin must be taken into consideration when determining the economic feasibility of marketing such eggs. Eggs higher in Vitamin E are currently available in stores.
LOW CHOLESTEROL EGGS
• Normally, a large egg contains approximately 200 to 220 mg of cholesterol. Lowering egg cholesterol in egg can be brought out by dietary manipulation or pharmacological intervention (drugs).
• Drugs have been successful in lowering egg cholesterol by as much as 50%.
• Drugs lower cholesterol in the egg by either inhibiting the synthesis of cholesterol in the hen or by inhibiting the transfer of cholesterol from the blood to the developing yolk on the ovary.
• At present, the drugs which have shown promise in lowering cholesterol are not yet approved by the FDA for commercial use.
• Chromium supplementation to laying hen diets at concentrations of less than 1 ppm have been shown to lower egg cholesterol and also improve egg interior quality.
• The most effective way to lower egg cholesterol content is to lower the energy consumption of the hen. Therefore, feeding hens with aspecial all-vegetarian diet that is higher in protein and fibre, and enriched in vitamin E can result in the production of low cholesterol eggs.
FAT AND FATTY ACID ENRICHMENT
• Consumption of polyunsaturated fatty acids has been reported to reduce the risk of atherosclerosis and stroke in human. Consumption of these fatty acids has also been shown to promote infant growth.
• Altering the total fat content in the diet of the hen has little effect on the total fat content of the egg yolk. However, the fatty acid profile (or the ratios of the different types of fatty acids) of egg yolk lipid can easily be changed, simply by changing the type of fat used in the diet.
• Different feeds, such as flax seed (linseed), safflower oil, perilla oils, chia, marine algae, fish, fish oil, and vegetable oil have been added to chicken feeds to increase the omega-3 fatty acid content in the egg yolk.
• Omega-3 fatty acid-rich eggs may provide an alternative food source for enhancing consumer intake of these ‘healthy’ fatty acids.
• Evaluation of the eggs during storage indicates that the shelf life of the enriched eggs was comparable to that of typical eggs.
• Omega-3 fatty acid-enhanced eggs are available in the market under various brand names.
• Omega-3 fatty acid-enriched eggs taste and cook like any other chicken eggs available in the grocery store. However, they typically have a darker yellow yolk.
• There are also designer eggs on the market that contain a lowered saturated to unsaturated fatty acid ratio. Canola oil is commonly used to alter the ratio of saturated to unsaturated fatty acids. Eggs containing 25% less saturated fat than regular eggs can be produced by feed manipulations.
MINERAL ENRICHMENT
• The shell contains the majority of the minerals in an egg. There are approximately 2,200 mg of calcium and 20 mg of phosphorus in the shell. There has been very little success in changing the calcium and phosphorus content of the albumen and yolk.
• It is possible, however, to increase the content of selenium, iodine and chromium. This has been done through dietary supplementation of the hen. These three minerals are important in human health. Therefore there has been some interest in producing designer eggs rich in these minerals.
PIGMENT ENRICHMENT
• The colour of the yolk is a reflection of its pigment content. In addition, the type of pigment in the egg and its concentration are directly influenced by the dietary concentration of any particular pigment.
• Consumer preferences vary greatly on yolk colour, even in the same country. Colour is described on the basis of the Roche Colour Fan (RCF). Yolk colours from 6 to 15 can be achieved by using only natural pigmenters obtained from natural raw materials.
• Natural sources can be from plants such as marigold, chili, or corn. The high protein blue-green algae known as Spirulina has also been shown to be a very efficient pigment source for poultry skin and egg yolk.
• Pigment enriched eggs may be beneficial in preventing macular degeneration, a major cause of blindness in the elderly. Higher intake of carotenoids reduced the risk of age-related macular degeneration. The most effective carotenoids were lutein and zeaxanthin, which are commonly found in dark-green leafy vegetables, such as spinach and collard greens.
• Most of the carotenoids in egg yolk are hydroxy compounds called xanthophylls. Lutein and zeaxanthin are two of the most common xanthophylls found in egg yolk.
• Lutein and zeaxanthin are high in pigmented feed ingredients such as yellow corn, alfalfa meal, corn gluten meal, dried algae meal and marigold-petal meal. Both lutein and zeaxanthin are efficiently transferred to the yolk when these various feed ingredients are fed to laying hens.
• The egg processing industry has routinely produced highly pigmented yolks for use in bakery products, pasta and mayonnaise. The dark yolk colour has better acceptance by Indian consumers. With a growing problem of macular degeneration in the elder people, there is a great market potential for these eggs.
BIO-PHARMING
• Developing genetically modified chickens by biotechnology tools that produce compounds that can be harvested from the eggs. These compounds include insulin for the treatment of diabetes.
• The hen, like all animals, produces antibodies to neutralize the antigens (viruses, bacteria etc.) to which she is exposed to each day. These antibodies circulate throughout her body and are transferred to her egg as protection to the developing chick.
• The hen can develop antibodies against a large array of antigens and concentrate them in the egg.
• Specific antigens can be selected and injected into the hen for developing antibodies against them.
• Chicken can synthesize and deposit interferons, monoclonal antibodies, recombinant human antibodies against autoimmune diseases, and cancer etc. in their eggs.
