An important role is played by diet in maintaining health. Egg provides essential nutrients to the body it is rich in minerals, vitamins, essential amino acids and fatty acids. Designer foods of animal origin are produced either by feeding specific diets or using new techniques like crossbreeding and genetic engineering. Designer eggs are a type of functional food. The egg composition can be altered by genetic composition and nutritional manipulations which can be done by modifying lipid profile, fatty acids, amino acids, minerals and cholesterol concentrations and their fractions or through adding therapeutic pharmaceutical molecules. Designer egg provides organic foodstuff which has improved minerals, and vitamins, lowers total cholesterol, and balanced ratio of omega-3 and omega-6 fatty acids and essential pigments such as carotenoids designer eggs are those in which the content has been modified from the standard egg in terms of high vitamin and minerals, lower cholesterol, high omega fatty acids and added pharmaceutical compounds.
An avian egg is a highly integrated biological system. The nutritive value and functional properties of an egg make it an important item in the human diet. Eggs and egg products form an integral part of the food chain. It is the only animal protein source in developing countries that is available to the general population. The egg is the source of protein, liposoluble vitamins A, D, E, K, and vitamin B-complex such as cyanocobalamin, thiamine, riboflavin, niacin and pyridoxine. Among minerals; it contains iron, calcium, potassium, sodium, phosphorous and zinc. The egg is also an important source of dietary cholesterol which increases serum cholesterol that ultimately causes the appearance of coronary diseases. The association of cholesterol with coronary diseases has raised concerns among consumers and somewhat lowered its consumption in a certain section of society. The consumption of cholesterol-rich food by diabetic patients, cancer carriers and hypercholesterolemia patients can raise the risk of coronary diseases. Egg yolk has a high concentration of lipids. Thus, it will be of interest to develop products derived from or nutrients within eggs through some nutritional manipulations that help to maintain consumer health. Generally, designer eggs are produced by modifications in layer diets and by technological methods. Designer eggs can provide more than 600 mg of omega-3 polyunsaturated fatty acid and 6 mg of tocopherol.
An average-sized egg contains 180-200 mg of cholesterol. Supplementations of chromium to layer diet at a concentration of less than 1 ppm have been shown to lower cholesterol. Further, a diet rich in protein and fibre fortified with vitamin E can produce eggs lower in cholesterol. Supplementation of the Gynura procumbens plant (longevity spinach) in laying hen diets decreased cholesterol by 12% in egg yolk. Diets rich in alfalfa meal (Medicago sativa) reduce cholesterol by 19%, this plant is effective in decreasing the reabsorption of biliary cholesterol in the intestine of birds further decreasing the cholesterol level in egg yolk. A combination of alfalfa and flax seeds can also lower cholesterol in eggs by 9% which affects cholesterol synthesis. Supplementation with a combination of flax seed, spirulina and vitamin E; fish oil and selenium; flax seed, spirulina and vitamin E + fish oil and selenium decreases egg yolk cholesterol levels by 23.2%, 26.4% and 22.5% respectively. Supplementation of hemp seed also reduced egg yolk cholesterol by 32% due to the presence of phytosterol lower absorption of cholesterol from the intestine and inhibits cholesterol synthesis in the liver.
Improved yolk colour and pigments
The colour of egg yolk is an indicator of pigment content which may vary based upon dietary supplementation such as maize, marigold, alfalfa and blue-green algae i.e. spirulina. These are carotenoids rich plants. Thus, supplementing poultry diets with such plants increased the concentration of yolk carotenoids. Eggs with highly pigmented yolks are used in preparing mayonnaise, pasta and different bakery products. With supplementation of Phaeodactylum, Nannochloropis and Isochrysis the yolk colour was shifted from yellow to red colour. Yolk colour and carotenoid pigments are correlated positively. Beta carotene has no influence on yolk pigmentation whereas lutein and zeaxanthin are highly active yolk colourants.
Eggs enriched with vitamins and minerals
Manipulation in the diet improves the levels of iodine, selenium and chromium in eggs without affecting calcium and phosphorus levels. Supplementation of chromium reduces yolk cholesterol whereas selenium levels in eggs can be increased by incorporating Yeast Se in the diet of layers. Designer eggs have 26 times more vitamin E, 16 times more vitamin A and 7 times more selenium which boost human intake of natural antioxidants like folate, vitamin E, lutein, zinc, selenium, carotenoids, pigments, and lecithin to enhance immune response. The inclusion of designer eggs in human diets by 12-16 eggs per month increases vitamin E consumption up to levels of 23 mg per day.
The improved fatty acid profile
The ratio of saturated to unsaturated fatty acid can be changed using canola oil in the feed. Designer eggs have a balanced ratio of Poly unsaturated fatty acid: saturated fatty acid (1:1) or omega-6: omega-3 polyunsaturated fatty acid (1:1). Omega-3 polyunsaturated fatty acid is important in the development of the nervous system and also modulates immune function, in addition to anti-tumour, anti-inflammatory and cardio-protective effects. These also lower blood platelet aggregation, blood pressure, and the incidence of thrombosis and atherosclerosis. Omega-3 content in eggs can be increased by dietary supplementation of groundnut oil, fish oil, safflower oil, linseed oil, fish meal or marine algae.
Antibodies and other products
Developing genetically modified chickens will produce eggs with benefits such as insulin for diabetes treatment. Transgenic hens could be used to produce antibodies in egg albumin. Egg yolk antibodies are antigens specific to antibodies in the yolk which could be obtained by injecting specific antibodies resulting in the production of IgY antibodies subcutaneously or intramuscularly. Thus, eggs can be utilized as an immunogen source which will improve the immune system. These can also be used as antiviral and antibacterial agents in animals as well as humans to treat E. coli infections, corona and rotavirus infections. Egg yolk antibodies can also be used as anti-venom against snake poison. Therefore, designer eggs are the source of immunoglobulins that strengthens the immune system.