A survey of 30,000 consumers of different countries was carried out regarding their concern about the food ingredients, genetically modified food and organic food (news reporter of USA today). The healthy and clean food is their demand irrespective of their high cost. They are committed to maintain an active and healthy lifestyle, avoid of serious health and medical issues. Healthy lifestyle is always related to nutrient requirement. Poor nutrition not only retarded the physical and mental growth but also the immunity. Having varieties of food neglecting the fruits, vegetable and fibrous food can be an imbalance diet. The balanced diet can be defined as the diet which provides all the nutrients in required amounts and proper proportions.
Malnutrition is a result of imbalanced diet.Nutrition is important for everyone but requirements varies from person to person, depending upon certain factors such as age, gender, body weight, nutritional requirements, physical activity etc. Therefore, the health and nutrition are the most important factors for proper development.Incorporating vitamins, essential fatty acids (EFA), antioxidant, growth promoters improve the quality of food. The growing need of human nutrition in the prevention and treatment of several chronic diseases has drawn the attention of government in improving the quality of food in order to fulfill the basic nutritional requirements of the consumers. In response to that, several food industries are working on a broad range of food products such as eggs and meat by manipulating their nutritional profile to fulfill the increasing demand of the consumers for superior foods.
Eggs are considered as the nature’s most complete food containing high quality proteins, saturated fats and unsaturated fats in the ratio of 1:2, and also an excellent source of Fe, P, and other minerals including vitamins. Egg is basically a cholesterol rich food containing about 210 mg of cholesterol in its yolk. However, fulfilling the demand of the consumer is to reduce the cholesterol content and enhancing the growth promoters in the egg brought the concept of designer egg.
Designer eggs can be defined as the standard eggs which have been modified or designed in such a way that can fulfill the consumer’s requirements and the present market demand. Designer eggs are the normal eggs fortified or nutrified with health promoting ingredients.In this approach, various essential nutrients are incorporated to the egg according to the consumer’s choice. The enrichment of several growth promoting substances such as fatty acid profile, vitamin E, immunomodulator, anti-oxidants, minerals, pigments etc.
Figure: Manipulation of different nutrient profile in designer eggs
Dietary manipulation of poultry
Designer egg can be developed by supplementing the poultry diet with the desired nutrient to be incorporated to the egg.
Manipulation of fatty acid profile in eggs:
Omega-3 fatty acids belong tothe family of polyunsaturated fatty acids (PUFA) and derived largely as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from fish oils and as α-linolenic acid (LNA). Omega-3 fatty acids can be derived primarily from two sources i.e., Marine and Terrestrial source. It plays a very vital role against cardiovascular disease, hypertension, autoimmune, allergic, and neurological disorders and is also important for normal functioning of the human physiology in normal adult and pregnant as well as lactating women. It has been proven that a diet balanced in omega-3 and omega-6 fatty acids is very essential. Since the ratio between omega-6 and omega-3 in eggs can easily be manipulated through diet enrichment in chickens. Scientists have developed designer eggs by incorporating omega-3 PUFA into eggs in order to get the desired dietary ratio of omega-6 and omega-3 PUFA.
Reduction of Cholesterol level:
A large or a moderate size of egg contains about 213 mg of cholesterol in its yolk. Supplementation of feed with 1.5% menhaden fish oil or 5% whole or ground flaxseed based diet can reduce the yolk cholesterol level upto 9% (Scheideler and Froning, 1996). A decrease of 16 to 33% cholesterol level in blood plasma and egg yolk reported when fed with phytosterols (Sim and Bragg, 1977). Yolk cholesterol can also be reduced by supplementing with diatary micro minerals such as copper, chromium, zinc, iodine and vanadium.The cholesterol level in egg yolk can be significantly reduced by 10-25% by manipulating chicken’s feed, supplementing with herbal plants products such as basil, bay leaves, citrus pulp (nirangenin), garlic, grape seed pulp, roselle seeds, spirulina, tomato pomace (lycopene) etc. Supplementation of laying hen diet by multi-strain probiotics (0.5g/kg) can also lead to the significant reduction of yolk cholesterol level.
Requirement of all the health conscious people is functional food with high nutritional value.If the health beneficiary nutrients are incorporated into the eggs can eventually reduce the chances of occurrence of various diseases and thus will be the best choice for health conscious people.Phytobioticsconsists of several secondary metabolites which can be used as poultry feed in order to produce herbal enriched designer eggs.
Vitamin E enrichment:
Designer eggs with higher amount of vitamin-E content is generally recommended in order to extend the shelf life of the product by preventing the egg lipid rancidity. Vitamin-E reduces free radical in blood and also reduces the risk of heart disease.
Designer eggs fortified with carotenoid pigments is a new concept to the field of science and technology. Since the color intensity of the yolk is directly proportional to the amount of pigment present in the egg, therefore higher the amount of pigment, more intense will be the color of yolk. Moreover such eggs have special interest because of consumers’preference.Theyolks with more intense yollow color over pale yellow yolk have high market value. There are a number of natural carotenoid pigments such as carotenes, xanthophyll, cryptoxanthin, zeaxanthin, lutein which can be used for the fortification of eggs. These carotenoid pigments are found to be present in alfalfa, corn gluten meal, blue green algae-spirulina, marigold petal meal and capsicum which are responsible for the attractive yellow or orange color of the yolk.
Essential minerals can be incorporated into eggs through dietary manipulation thus producing designer eggs enriched with minerals. This includes minerals like Selenium, iodine, chromium and copper. These minerals are very important for our health, deficiency of which can lead to the emergence of various diseases.
- Selenium enrichment
Selenium is one of the very important micro nutrients which plays a very vital role in our body. Normally in eggs, selenium exist in the form of seleno-proteins which is mandatory for normal growth and development of the body. Designer egg enriched with selenium was first developed in Scottish Agriculture College, 1998 by manipulating poultry diet, supplementing with organic selenium (Se enriched yeast). The supplementation of selenium can decrease the risk of incidence of cancer, arthritis, cataract, cholestasis, cystic fibrosis, diabetes, lymphoblastic anemia, mascular dystrophy etc. and also helps in the betterment of the quality of semen in sub fertile males,
- Iodine enrichment
Iodine is a very important micronutrient which is required for normal human growth and development. Deficiency of nutritional iodine can cause goiter, hypothyroidism, cretinism, decreased fertility rate, increased infant mortality rate and mental retardation. In developing countries like India, China and many other countries, people are suffering from such iodine deficiency disease, therefore designer eggs enriched with iodine content can provide adequate amount of iodine to our body thus proven to be a good source of iodine. A typical designer egg enriched with iodine contains approximately 700 μg of iodine which is important for our body metabolism.
A typical poultry egg contains natural antioxidants like vitamin E, carotenoid pigments, flavinoid compound, lecithin etc. Antioxidants present in the eggs helps in protecting the yolk lipid from oxidative rancidity; but it was observed that in spite of the presence of such natural antioxidants, eggs are still susceptible to oxidative rancidity. Therefore designer eggs were developed in order to increase the shelf life of the eggs which are enriched with not only the above mentioned natural antioxidants but also high levels of certain synthetic antioxidants such as Ethoxyquin and anti-oxidants of herbal origin such as Carnosine, Curcumin, Lycopene, Quercetin and Sulforaphene, obtained by manipulating poultry diet. Such designer eggs enriched with antioxidants are less susceptible to lipid peroxidatio and also prevent destruction of fat soluble vitamins.
Naturally eggs contain certain antibodies like G1, G2 and G3-globulin which are considered to be very important antimicrobial and immunostimulating agent. Chicken egg is abundant in antibodies like "IgY"; can be used to treat human rotavirus, E.coli, Streptococcus, Pseudomonas, Staphylococcus and Salmonella infections. The efficiency of immunomodulating agents in eggs can be further increased through dietary manipulation of poultry feed by supplementing them with certain herbs like rosemary, turmeric, garlic, fenugreek, spirulina, ashwagandha possessing immunomodulating properties.
Production of designer egg through gene manipulation:
Genetic engineering refers to the direct manipulation of organism’s genes using recombinant DNA technology. Genetically modified organisms have special interest in the field of biotechnology and medical science. The first animal to be genetically modified were mice which is then followed by rabbit, sheep and pigs. At first pronuclear DNA microinjrection method was used in order to produce genetically modified organism, but later, it was observed that this gene manipulationmethod leads to random integrations and ultimately giving rise to some unwanted product, therefore the concept of knock out (KO) animals was introduced. However, genetic manipulation of chicken embryo is problematic due to its complex zygote structure as compared to mammals. The first genetically modified chicken was developed by insertion of retroviral foreign DNA using avian leukosis virus that is successfully integrated to the germline. The retroviral vector is injected into the yolk sac near to the developing blastoderm.