Dietary Manipulation in Commercial Layer Poultry Birds for Improvement of Egg Quality

May 18, 2023

1064

Dietary Manipulation in Commercial Layer Poultry Birds for Improvement of Egg Quality

Nutritional quality of eggs is also affected by type of feed consumed by birds. Quality of feed can be enhanced by following dietary manipulation.

1. Egg yolk is considered one of the richest sources of cholesterol in human diet. Normal cholesterol content of eggs (about 200-250 mg) and blood (around 150mg %) in chicken has been found to vary quite considerably. The cholesterol content of chicken egg can be reduced up to 25 % through the use of additives, dietary fibre and polyunsaturated fatty acid supplementation.

2. Omega-3 fatty acids have cardio protective and other beneficial effects. Poultry nutritionists have started research to incorporate more of these fatty acids in the egg and have succeeded in developing such an egg called Omega-3 enriched ‘designer egg’. This egg can be called as the ‘diet egg’ or the ‘functional egg’.

3. Diet eggs can have a high percentage of Vitamin E, an antioxidant, which prevents oxidation of cholesterol and therefore its ill effects. These eggs may also contain 600 mg of Omega-3 fatty acids. Omega-3 fatty acids help to reduce cholesterol triglycerides, clog formation, tumour growth and improved immunity.

4. In order to improve the quality of these eggs further selenium, carotenoid pigments, etc. are also being increased in these eggs.

What is Egg Quality

As a result of the large diversity in the potential uses of eggs and the subsequent demands of the consumer, it is quite a challenge to define egg quality according to everyone’s standard.

Kramer (1951) has defined quality as “the sum of characteristics of a given food item which influence the acceptability or preference for that food by the consumer”. Based on this definition, it is clear that egg quality will mean different things to different people as the consumer’s perception of quality varies depending on their intended use of the egg and their own preferences. There are a number of factors we, as a breeding company, focus on when it comes to egg quality. What are these factors and how do environmental factors impact quality?

Eggshell quality

The vast majority of eggs sold in the world are sold in their shell (table eggs), therefore the consumers’ first impression is based on their perception of shell quality. Shell quality can be split up in several categories.

Eggshell integrity

Defects considered under this category includes cracks and thin shelled, or shell-less eggs. Eggs with cracks are sorted out during the egg grading process as cracked eggs are more prone to microbial contamination. The biggest cause for cracks is via mechanical damage, that could by caused by the birds themselves, or as a result of poor management practices like infrequent egg collection, poor design of the housing system and egg belt or running the feed chain during the peak hours of egg production (disturbing the birds on the nests).

Eggshell strength plays an important role as weaker shelled eggs are more prone to breakages and cracks. Shell strength is affected by a wide range of factors:

Egg size: in general, smaller eggs have stronger shells. Unfortunately, hens have a finite capacity to deposit calcium during eggshell formation and as a result, the same amount of calcium needs to be divided over a larger area.
The hens’ age: young hens have a higher chance to produce shell less eggs as their shell glands have not yet matured, besides, young hens have a higher tendency to produce double-yolk eggs during the first weeks of production. As eggs grow bigger when hens are getting older, shell strength goes down (see above
Stress event: a single stress to your flock can be enough to disturb the process of egg formation for several days. Stress can easily result in soft or thin-shelled eggs, or in misshapen eggs. In worse cases, the egg can break while still in the oviduct.
Heat stress: high temperatures inside the poultry house often reduce feed intake, and thereby reducing calcium intake which results in an insufficient amount of calcium available for proper eggshell formation.
Nutrition: adequate dietary minerals and vitamins are essential for good eggshell quality, the role of drinking water in the supply of minerals and trace elements should not be overlooked. The hens’ diet should be well balanced with the proper amounts of calcium and phosphorus available as calcium and phosphorous are essential in forming the eggshell.
Vitamin D: Vitamin D plays an important role in the proper utilization of calcium and phosphorous, a lack of Vitamin D in the diet results in weaker eggshells and weaker bones.
Diseases: the most well-known disease affecting eggshell quality is Infectious Bronchitis (IB), which is caused by a coronavirus which attacks the mucus membranes of both the respirator and the reproductive tracts. Also the adenovirus that causes the Egg drop Syndrome (EDS) results in thin-, soft-shelled or shell-less eggs.
Genetics: the heritabilities of shell strength are moderate (h² in the range of 0.25 – 0.35). Eggshell breaking strength is an important trait in our breeding programs and intensive genetic selection for more than half a century has resulted in hens that are able to produce eggs with higher breaking strength and maintain these high levels for longer production periods.

Eggshell Texture

Rough shells, pimples, pinholes and mottled shells are all eggshell defects associated with the texture of the eggshell. The main factors are:

Disease: Infectious Bronchitis (IB), infectious laryngotracheitis (ILT) and avian encephalomyelitis (AE) can be linked to the occurrence of textural defects.
Genetics: in our breeding program we record all these deviations, although heritabilities are low to moderate (h² in the range of 0.05 – 0.25) we make steady progress with every new generation.
Management: inadequate water supply, sudden changes in lighting programs, poor ventilation and too high stocking densities can all result in an higher incidence of shell defects.

Shape

The shape of an egg is extremely important as the proper egg shape gives a better fit in the egg boxes and egg trays. Misshapen eggs have a shape which differs from the smooth normal shape, think of flat sided eggs, body checked eggs, and the Ping-Pong ball shaped eggs. Main factors related to misshapen eggs are:

Disease: Infectious Bronchitis (IB), Egg Drop Syndrome (EDS), Avian Influenza (AI) and New Castle Disease (NCD) are all linked to result in a high incidence of misshapen eggs as they negatively affect the albumen quality, whilst the albumen and its surrounding membranes provides the structure on which the eggshell is deposited.
Stress: overcrowding, stress, poor lighting patterns and improper handling can result in body checked eggs and flat sided eggs.
Age: young birds, with shell glands that are still immature, may produce misshapen eggs.

Color

Eggshell color is primarily determined by the breed. Leghorns produce white eggs, Rhode Island Reds brown eggs and a cross between the aforementioned tinted eggs. Besides, there are all the specialty breeds which produce chocolate brown, green or blue eggs. Any factor which causes a disruption will affect the color and the color uniformity of the eggshell. These factors are:

Stress: Epinephrine, a stress hormone, will cause a delay in oviposition and cessation of shell gland cuticle formation, which can cause pale shelled eggs to be produced. Stressors may include, amongst others, high cage density, loud noise and handling
Age of bird: As birds age increases, the intensity of pigment decreases. This may be due
to decreasing production of pigment or increased surface area over which available pigment is distributed.
Disease: New Castle Disease (NCD) and Infectious Bronchitis (IB) are both examples of viruses which affect the mucus membranes of the respiratory and tract. They cause the shell to become abnormally thin and pale.
Genetics: eggshell color is heritable, heritabilities are moderate to high (h² in the range of 0.35 – 0.6). Breeding directions are clear: white eggs are selected to become whiter, brown eggs to become darker and to decrease the natural drop in eggshell color as much as possible as the hen is aging.

Cleanliness is probably the easiest aspect of eggshell quality to control; proper management plays an important role in keeping your eggs clean. Most eggs are clean when laid and subsequently become contaminated with fecal material or other contaminants.

Management: Good management practices can help to reduce the number of dirty eggs. These practices include frequent collection of eggs, as well as regular maintenance and cleaning of cage and nest floors, egg belts and roll out trays.
Nutrition and gut health: factor which causes diarrhea in the birds will also result in an increase in the number of dirty eggs collected.
Blood smears on eggs can be minimized by good pullet management, including weight for age and proper lighting programs. Do not force and stress your hens to come into lay!

Internal egg quality

Unlike external (shell) quality, internal quality of the egg begins to decline as soon as the egg is laid. Egg handling and storage practices have a significant impact on the quality of the egg, it is the internal quality of the egg that is most important to the consumer. The aspects of internal quality are significantly more difficult to observe or evaluate in the intact egg. Internal egg quality can be split up in the following:

Yolk quality

Yolk quality is determined by its color, texture, firmness and smell of the yolk. The primary determinant of yolk color is the xanthophyll (pigment) content of the diet consumed. It is easy to manipulate the yolk color of eggs by the addition of xanthophylls to the diet.

Pale yolks can result from any factor which alters or prevents the absorption of pigments from the diet or the deposition of these pigments in the yolk. These factors could be:

Worms
Decreased liver function
Coccidiosis

The yolk of a freshly laid egg is round and firm, however, as the egg ages and the vitelline membrane degenerates, water from the albumen moves into the yolk and gives the yolk a flattened shape.

Albumen quality

The quality of the albumn is related to the consistency, the appearance and its functional properties.

Haugh Units (HU): a measurement for the consistency of egg albumen. Haugh Units are calculated from the height of the albumen and the weight of the egg. Haugh units decrease with increasing bird age.
Genetics: the breed plays an important role in albumen consistency. All breeds show a decrease in Haugh Units over their lifetime, but there are breeds that start off with very high Haugh Units. Heritabilities for Haugh Units are moderate (h² in the range of 0.25 – 0.35).
Egg storage: As the egg ages and carbon dioxide (CO2) is lost through the shell, the contents of the egg become more alkaline, causing the albumen to become transparent and increasingly watery. At higher temperatures, loss of CO2 is faster and the albumen quality deteriorates faster. Frequent egg collection, and storage of eggs under cool temperatures will maintain longer Haugh Units.
Albumen color: excesses of vitamin B (riboflavin) can cause the albumen to become green. Long storage under poor conditions results in yellowish albumen.

Blood spots

Blood spots may vary from indistinguishable spots on the surface of the yolk to heavy contamination throughout the yolk. Blood spots are normally associated with the yolk, but occasionally, blood may be diffused through the albumen as well. Blood spots occur when small blood vessels in the ovary rupture when the yolk is released. Major causes are:

Vitamin K deficiency, as this plays an important role in blood clotting, and resulting in an increased occurrence of blood spots.
Genetics: differences occur between genetic strains. In our breeding program we select against blood spots, but heritabilities are low (h² 0.05-0.10).

Meat spots

These are usually associated with the albumen rather than the yolk and often consist of small pieces of body tissue. Some may consist of partially broken-down blood spots or pigments. The occurrence of blood spots varies with strain of bird, increases with the age of the birds and is higher in brown egg layers. In our breeding we select against meat spots, but as with blood spots, heritabilities are low (h² 0.05-0.10).

Continuous investment in our breeding program has resulted in genetic progress for both egg production and quality. Our people are passionate about raising the bar in genetic selection by using the latest tools in data collection and examining egg market needs.

Optimising egg size in commercial layers

Each commercial variety has a genetically determined range of egg size, and within this range, environment plays an important role in the expression of egg size. Genetics, body weight management, nutrition, and lighting programs are the four pillars of egg size and are useful tools for the egg producer to change egg weight profiles to best supply the optimum egg size to a market.

Genetics

Hy-Line is working at the genetic level to create commercial lines that have different egg size ranges. Egg weight is a heritable trait (~40%) that responds well to genetic selection. About 60% of egg size variation, however, is due to non-genetic factors (nutrition, management, etc.). These non-genetic factors can be manipulated by egg producers to achieve the desired egg size profile.

Hy-Line has been collecting egg weight data and selecting on egg weights for decades. Historically, egg weights have been collected periodically throughout a hen’s lifetime. Currently, Hy-Line weighs the first three eggs a hen lays, eggs laid mid cycle, and eggs laid late in the cycle. The Hy-Line Research department uses these egg weights to select for a more desirable shape to the egg weight curve. Specifically, they select to increase early egg weights, hold mid-cycle egg weights constant, and decrease late egg weights (Figure 1).

Egg numbers and breaking strength have a negative correlation with late egg weight. As Hy-Line varieties continue to improve late persistency and shell strength, the egg sizes at later ages will come down. To help adapt to this selection pressure, Hy-Line is relaxing the selection pressure to reduce late egg weight to ensure that sufficient egg size and egg mass is available in the genetic potential of the birds.

Body weight

An important factor in egg weight is the pullet‘s body weight at maturity. Heavier hens tend to lay more eggs throughout the production period and will have greater flexibility in adapting different egg size profiles. Body weight is affected by many factors, including beak trimming, vaccination program, transfer, disease challenges, pullet lighting program, space allotment, and nutrition. Due to the direct affect of body weight on egg weight, the achievement of flock target body weight with good flock uniformity is important for egg size management.

Nutrition

Nutrition during the rearing and laying period has a critically important role in egg weight. Proper rearing nutrition allows the hen to achieve or exceed the standard body weights. Changing the rearing diets based on attaining body weight standards (and not bird age) will best match the diet to the actual nutritional needs of the pullet.

During the laying period, the specification of diets can be used to manage egg size. Energy, methionine/cystine, other digestible amino acids, linoleic acid, and total fat can directly affect the egg size. These components can be specified in layer diets to influence egg size downwards or upwards.

The protein content of the diet should be balanced to ensure the amino acids are utilised efficiently by the bird. Unbalanced protein can result in poor utilisation of amino acids and suboptimal egg size.Breghendahl (2008) estimated the “ideal amino acid profile” and determined that the ratio of methionine to lysine should be a minimum of 47:100 to support maximum egg mass. All other amino acids should be balanced relative to lysine to ensure egg size is optimised as efficiently as possible.

To avoid excessively large egg size and weak egg shells later in the laying period, these nutrients are gradually reduced after peak egg production (30 weeks of age). Pushing nutritionally for greater egg size could result in thinner shells and more cracked eggs if mineral requirements of the bird are not adequately provided for.

Management for larger egg size should include nutritional considerations in rear for subsequent shell quality and bone strength (i.e. pre-lay diet).

Egg weight can be regulated through use of a phase feeding regime. Optimal egg weight will be easier to achieve when formulating feed according to egg weight or egg mass and constantly updating the formulas according to these parameters. This tool can be very helpful either to increase egg weight on earlier production, or to control egg weight on late production.

Be aware that not only nutritional levels, but all aspects of nutrition management can affect egg size. Feed particle size, water intake, water temperature, and feeding schedule can affect daily feed intake and nutrient intake as a consequence.

Heat stress can depress egg weight. High environmental temperature above the thermoneutral zone (> 33°C) has a depressing effect on the bird’s feed intake. The result can be a shortfall in nutrients like protein (amino acids) and energy, which will decrease egg weight. It is common to see decreased egg size as a consequence of heat stress. Appropriate adjustments in feed formulation to match the actual bird feed intake and mitigation of heat stress conditions can minimise this depression of egg size. In environmentally controlled houses, lowering the environmental temperature will increase feed intake and support egg weight.

Lighting programs

Chickens are responsive to changes in day length, and this has a significant effect on egg production and egg size (Figure 2). Slow step-down lighting programs (C and D) during the rearing period provide the pullet with more light hours to eat and grow. At the same time, these slow step-down lighting programs can also delay maturity and increase egg size.

Faster step-down lighting programs (A and B) provide fewer light hours and slower growth but earlier sexual maturity with smaller egg size.

Age of light stimulation and body weight are interacting factors that help determine the onset of egg production, as well as egg size. Light stimulation should be done based on the flock’s body weight and uniformity. Generally, early light stimulation at lighter body weights will accelerate maturity and decrease egg size; while later light stimulation at heavier body weights will delay maturity and increase egg size. Generally, the hen has the ability to produce a certain egg mass. As egg weight is changed, the egg number tends to change inversely to keep the egg mass constant.

Management tips to optimise egg size in a market

Management for larger egg size:

Select a commercial variety with a heavier egg weight profile. Hy-Line W-80 Plus is the large egg version of W-80. The Hy-Line Brown can be customized to influence the egg weight profile.
Use a slower step-down lighting program in rear. (12 weeks)
Light stimulation at a heavier pullet body weights. (W-80 Plus: 1.25 kg; Hy-Line Brown: 1.40 kg; W-36: 1.27 kg)
Make smaller gradual reductions in energy and methionine/cystine during the phase feeding program.

Use feed formulation that provides 10–15% higher digestible amino acid intake (mg of digestible amino acid per bird per day) than recommended in the Hy-Line guide. Increase the ratio of methionine + cystine to lysine to be >90%.
Linoleic acid has a positive impact on egg size. For increased egg size, use 1.5 g linoleic acid per bird per day. Use sources of supplemental oil which are higher in linoleic acid, like soybean oil or flaxseed.
Increase total and supplementary fat content in the diets. Studies have shown that at the same linoleic acid levels, birds consuming a higher amount of total fat will produce larger eggs.
Keep an optimal energy intake. In situations of deficient energy intake, laying hens will utilize protein and amino acids as an energy source, resulting in less amino acids available for optimal egg size. Many situations of low egg weight are due to low energy intake. Overfeeding energy above recommended amounts tends to depress egg weights, as a consequence of lower feed intake.

Management for smaller egg size:

Select a variety that has a regular egg weight profile. (Hy-Line Brown, Silver Brown, W-80, or W-36)
Use a faster step-down lighting program in rear. (7 weeks)
Light stimulation at a lighter pullet weight. (W-80: 1.17 kg; Hy-Line Brown: 1.30 kg)
Make larger gradual reductions in energy, methionine/cystine, and total digestible amino acids during the phase feeding program.

Nutritional management for controlling egg size is more complex and generates slower results than managing for increased egg weight.
Reduce methionine + cystine to lysine ratio (<84%). This reduction should be done gradually to avoid reduction of egg production as well.
Control total digestible amino acid intake. Studies have shown that a reduction of intake of all amino acids can be more effective in controlling egg weight than reducing only methionine and methionine + cystine.
Limit linoleic acid intake to 0.9 g/day per bird. Change to an oil source with lower linoleic acid content, such as palm oil.
Start to control egg weight with phase feeding at least 2–3 g before the desired egg weight. Provide clear objectives of the amount of cumulative amino acid intake per egg weight phase you desire.

How to increase egg size?

Increasing egg size is a significant objective in poultry farming as it is the method of classification for sale. Which factors are related to size, and how can we increase it?

Egg size grading

Hen eggs must be graded for marketing and pricing. Considering the variety of sizes, they have been graded by weight in grams. For this reason, there is a classification that equates weight and size.

Type of egg	Size	Weight in grams
Small	S	<53
Medium	M	53-63
Large	L	63-73
Super large	XL	>73

Table 1. Correlation between egg size and egg weight.

Increasing egg size: genetics

For decades, poultry genetic industry has carried out optimal and excellent selection processes. Selection makes it possible to obtain the maximum number of advantages and reduce the disadvantages of a genetic line of animals. These accumulated improvements are known as hybrid vigor.

Therefore, genetic selection influences the improvement of egg size. Other beneficial traits that have been obtained are disease resistance, rapid growth, nutritional efficiency, and earlier puberty.

Among the variables that control the improvement of egg size, genetics plays a 40% role. The other 60% of variables are non-genetic, also called environmental factors.

Nutrition is always a key factor

Nutrition is a component involved in boosting egg size. There are some specific nutrients which, when supplied correctly, help to produce larger eggs.

Amino acids: methionine and lysine

Methionine is one of the most studied amino acids that significantly contribute to egg size improvement. Combined with another amino acid, lysine, makes it possible to obtain larger or smaller eggs, as required by the producer. For this reason, providing these amino acids helps to increase egg size.

Energy and fat

The energy and fat in the feed must be correctly balanced by a professional, such as a zootechnician. If a feed has an excess of energy, it can result in a lower feed consumption by the hens and therefore a lower egg production. Sometimes it is better to increase the fat to provide the kcal needed by the hen, instead of increasing the energy to avoid this. This balance of energy content is beneficial for the improvement of egg size.

Linoleic acid

Studies have shown that an adequate proportion of linoleic acid has a positive effect on increasing egg size. This long-chain unsaturated fatty acid must be supplied in the right proportions for each stage of hen production.

Protein

Protein is an essential component of any animal diet and must be balanced correctly. It is important to remember that eggs are food with high protein levels. Therefore, the bird also needs a good amount of protein in its diet.

Age and weight of the hen

As the hen gets more weeks old, the eggs are getting bigger. When hens start their laying cycle, the eggs will be small at first and then medium size. As they get older, the eggs are getting bigger.

Another substantial factor in increasing egg size is the weight of the hen. Therefore, if the birds are fed with sufficient nutrients during the rearing stage, they will reach the laying stage in better condition. A recommendation is that birds reach and exceed standard bodyweight.

However, during the rearing stage, several organs continue to develop. During the first 6 to 8 weeks of life, birds should be fed with starter and growth concentrates. Once this stage is reached, the skeletal system will have completed its development, and the bird can continue to develop. At this point, at eight weeks of age, a development concentrate is given to aid in egg size improvement.

Nevertheless, basing these parameters on the age of the hens is not always accurate. It is better to consider only the standard bodyweight of the strain according to life stage. The important thing is to be within the average and even exceed it by 60-80g. This method has two advantages. First, it helps to avoid malnutrition or growth retardation. And, secondly, to prevent overweight. These factors must be considered to ensure an increasing of the egg size.

Effect of lighting

Lighting in poultry houses remains one of the most significant parameters assessed. The effect of light on poultry has been studied for years and it is known that affects their behavior and development. In other words, light affects the improvement of egg size in hens.

In general, there are two types of lighting. The first, called slow decrease, consists of supplying the birds with more hours of light. This results in the fact that the birds are having more hours available for feeding and nutrition. In the long-term, this benefits the producer as the birds gain more weight. Although the birds take longer to develop, there will be undoubtedly an improvement of egg size under the system of more daylight hours.

On the other hand, there is a fast decreasing type of lighting. In this system, there are fewer hours of light available each day for the birds. Therefore, the effect observed is that birds develop faster. However, under this method, the eggs are smaller in size. This system is most used in broiler poultry farming.

Lighting system	Lighting	Egg size	Bird development
Fast decay	16 hours light / 8 hours night	Larger	Slower
Slow decay	14 hours light / 10 hours night	Small	Faster

Table 2. Comparison of lighting types used in increasing egg size.

General bird health and intestinal health

The general health of the bird is a requirement to obtain an increase in egg size. The hen must remain free of stress, diseases, fear, injuries, among others. These pathological situations are detrimental to egg quality and the overall health of the hen. In order to achieve a good egg quality and size, it is essential to maintain the general health of the hen population.

Poultry farm health is related to vaccination and the prevention of infectious diseases. Some of these diseases directly affect egg quality and reduce egg size. It is advisable to create health and infectious disease prevention plans for hens.

In addition, to achieve high egg quality and increased egg size it is necessary to maintain proper intestinal health. The condition of the intestinal mucosa is a parameter that goes hand in hand with general health and nutrition. The intestinal epithelium is responsible for the absorption of all nutrients supplied in the poultry diet, so it must always remain in good condition.

Adding intestinal conditioner pronutrients in the diets can help to improve egg quality. These molecules of natural origin promote the condition of the intestinal epithelium by favoring its regeneration and functioning. This is reflected in an improvement of intestinal health, general health, and egg quality.

Conclusions

Increasing egg size is a constant goal in poultry farming. Egg size classification is an established international requirement. Considering production systems, and economic aspects, it is possible to play with the factors involved in egg size. The most important factors affecting the improvement of hen egg size are five. The first and second are genetics and nutrition. Third is the weight and age of the hen. Fourth is lighting. Finally, intestinal health should be considered as an important factor affecting hen egg size.

EGG QUALITY ISSUES & ANIMAL WELFARE IN INDIA

The best eggs really come from hens that spend their days outdoors in a natural environment and scratch for insects, seeds and earthworms in the soil. The egg you buy does not come from these hens.

Eggs have always been considered to be a standard safe food. Few people realise that every egg is different, and some may not be fit to eat at all.

An egg is made up of albumen, yolk and a porous shell made of calcium carbonate. The internal ingredients of an egg can be altered so that the natural composition changes by manipulating the feed of the hens.

For instance, in Japan, Omega 3 and iodine have been introduced into the eggs. This means that the quality of the egg depends largely on the food given to the egg layer, and the conditions she is kept in.

It is affected by many factors, before and after its laying. Everything from the weather, type of feed given to the hen, amount of water consumed by her, cleanliness of the surroundings, number of hours that she spends in daylight and even the way she breathes, can drastically change the composition of the egg.

The way an egg is handled, before it reaches your plate, could make it inedible. On average, a chicken egg should contain about six grams of protein and six grams of fat. To produce this level, it is essential that a laying hen receives a balanced diet, with adequate levels of protein, carbohydrates, fat, vitamins and minerals.Experts recommend a balanced ration containing 16 to 18 percent protein and approximately 3½ percent calcium, to promote strong eggshells.Laying chickens also require a constant supply of fresh, clean water, as water comprises more than half of an egg’s volume. The fact, that an egg’s natural composition can be manipulated, is well known to commercial poultry farmers.Chemicals are added to the food so that they produce eggs that are better looking and last longer. Baking soda and ammonium chloride are commonly added as dietary supplements to improve eggshell quality.

Potassium chloride is mixed with their water as it makes hens thirstier. The use of antibiotics is also common with Indian farmers, pumping hens with these from the day they are born.The best eggs really come from hens that spend their days outdoors in a natural environment and scratch for insects, seeds and earthworms in the soil. The eggs you buy do not come from these hens.To ensure high production, with a minimum of money, all hens are kept captive in small crowded cages with a strict controlled environment, no sun, no fresh air and water, chemical food and antibiotics.They are kept under continuous lighting so that they lay more eggs daily. How nutritious would the product of such a stressed body be?India has particularly poor egg quality. Indian poultry farms are known to be some of the worst in the world, with very low health and safety standards and little regard for public health concerns.

Investigations at poultries show hens covered with sores, badly fed, sitting in their own faeces, covered with spiderwebs, full of mites and lice, fed cannibalistically with the dead bodies of their own kind, cardboard, marble chips, fish meal and grain laced with antibiotics and pesticides.

This destroys the nutritional quality of the egg. Unhygienic rearing practices, and lack of quality control measures, is an open invitation for egg contamination.

Despite India being one of the three largest egg producers in the world, with 47 billion a year, they do not meet international standards, and Indian eggs are rejected for export due to chemicals in and outside the shells. Thick albumen, plump yolks and hard shells are what you should look for superficially.

Do buyers look at the thickness of the shell? Because a thin shell means that the mother has been ill. Diseases like infectious bronchitis, Newcastle disease, avian influenza and egg drop syndrome, affect the shell quality.

Infectious bronchitis virus causes soft/rough-shelled eggs, discolouration and wrinkling of the shell. The egg, as a result of disease, has pale egg yolks, runny egg whites and rough shells.A deformed eggshell means the chicken has had a number of serious diseases. The shell is formed by the activity of cells lining the oviduct and uterus. When the egg layer is under stress, the secretions of these cells become acidic.

In extreme cases, stress induced effects can result in eggshells that are misshapen and have excess deposits of calcium – a powdery “bloom” on the surface.During summer, the hen, already in a small stuffy cage, reacts by panting in order to cool herself. This produces a condition termed “respiratory alkalosis”.The pH of the blood becomes alkaline and the availability of calcium for the eggshell is reduced. The eggshell becomes thin shelled. The thickness of the shell plays a vital role in preventing bacterial penetration.Thus eggs with thin shells are more prone to microbial attack. An egg should have phosphorous, zinc, Vitamins A, B 6 ,B 12, folic acid, thiamine and Vitamin D.During heat stress hens eat less and calcium intake is reduced as a direct consequence of reduced feed intake. This causes an elevation of phosphorous in the blood. Calcium and phosphorus balance is critical for proper eggshell quality.But high levels of phosphorus in the blood inhibit the formation of calcium. When the Calcium and phosphorus ratio is out of sync, zinc and manganese decreases. Vitamin D decreases in a sick bird. So, the egg is left with very little in it.Due to the lack of exercise in these caged birds, the fat component increases, and then the fatty acid composition in the yolk changes from healthy to unhealthy. In free-range poultries – which simply means that they are not in cages, crowded on the floor – chickens have a hierarchy.Those down the chain often lay whiter shelled eggs, with poor internal quality, due to the stress that they are under. Many studies show that tap water containing sodium chloride has an adverse effect on eggshell quality. What hens eat is of crucial importance. Every hybrid layer bird should have a specially devised diet. That does not happen in India.

Feed nutrients are used by poultry owners without any knowledge of their nutritive value. They feed the cheapest food to their hens. If soya meal is expensive, they will replace it with cotton seed defatted cake and guargum, none of these has any nutritional value. When you eat eggs sourced from poultry raised on antibiotics and growth promoters, you ingest antibiotic-resistant bacteria.Heat cannot break down the antibiotic residues that remain within the eggs. When you fall sick, no antibiotic will be able to work on your disease. India has the largest number of people resistant to antibiotics, and the main reason is that our chicken/eggs carry them.After leaving the farm, the entire supply chain poses additional risks of contamination to the egg. Cracked eggs (about 6%) are particularly susceptible to outside contamination.

A 2005 study in Punjab found residue of hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) in eggs. These are both banned pesticides, and their presence on eggs is extremely dangerous to human health.

Another 2010 study, by S. Dey and S.K. Dwivedi from the Indian Veterinary Institute, found lead and cadmium in eggs. Their study noted that consumption of contaminated eggs could lead to heavy metal poisoning in children, resulting in IQ deficiencies and even mental retardation.Large scale egg handling invites salmonella and aflatoxin contamination. While most nations take measures to sterilise the egg surface from contamination, especially from Salmonella enteritidis, no measures are taken in India. In a recent study done in and around Hyderabad, eggs were collected from urban retail outlets and directly from poultry farms.

Salmonella bacteria was commonly found on shells and inside the eggs collected from urban retail outlets. Salmonella infection is a bacterial disease that affects the intestinal tract. Typhoid fever, food poisoning, gastroenteritis, enteric fever, are all types of Salmonella infection. It is linked to contaminated water or foods, especially meat, poultry, and eggs. Salmonella bacteria is abundantly found in poultry sheds, water tanks, drinking water and feed in poultry premises.The internal contamination of eggs, by Salmonella, is either because the shell is thin enough to be penetrated, or that the egg was contaminated by the infected reproductive organs of the hen. Eschericia Coli, Enterobacter aerogenes and Sheigella were the other bacteria found.

The FSSAI laws state that the eggshells must be free of blood rings, must not be soiled, or have faecal matter, and they must not be cracked. They have laid down the hygiene parameters that must be observed during production, processing and handling, which includes sorting, grading, washing, drying, treatment, packing, storage and distribution. They emphasise on storage conditions, like moisture and temperature, so as to reduce microbial contamination.No one even knows the laws. Poultry farmers, traders, exporters and even consumers, are unaware of the health risks of egg contamination. Abroad, every batch of eggs has to have the name of the poultry where they have come from. That is how the food inspectors were able to determine so quickly that the eggs, with fipronil pesticide in them, came from 18 poultries in Holland (Indian eggs have the same pesticide in them).In India you have no idea where the egg comes from. Egg consumption is encouraged by the Government. This makes their quality, and contamination, a major food safety issue.