Chickens are a popular source of protein, due to their low-cost of raising and dual use as meat and eggs for protein production. South Africans are especially fond of chicken and it represents the most consumed protein in SA. Seeing that eggs are an easy, accessible and economic way to produce home-grown protein it is fitting to dedicate a post entirely to the production of eggs.
Egg anatomy
Chicken domestication has resulted in an evolutionary misfit, where hens are capable of laying eggs without the presence of the cock. In the wild such a scenario would never occur as it wastes valuable energy (from the hen’s point of view of producing the eggs) and resources (loss of an egg that could have given rise to a breeding member of the species). Therefore, eggs used for consumption remain unfertilised (it also limits the gross factor of chancing upon an underdeveloped embryo).
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| Anatomy of amiotic/unfertilised egg |
Egg shell, inner and outer membranes: Theses are protective layers of calcium carbonate (shell) and collagen proteins (membranes). The pigment that gives the eggs their colour is deposited in the oviduct and is breed specific. Please see my Layers & Nest Business post for breed (and egg shell colour) information.
Chalaza: Suspends the yolk within the albumen
Albumen: The egg white that protects the yolk and provides nutrients to the developing embryo in fertilised eggs. It consists of 90% water and 10% dissolved proteins with low cholesterol ~1% rating.
Vitelline membrane: Protects the egg yolk and separates it from the albumen.
Yolk: Includes the nucleus of pander, germinal disc, yellow and white yolks. The nucleus of pander contains essential proteins for embryo development where the germinal disc gives rise to the embryo. Egg yolk contains 43% of the total egg protein as well as saturated & unsaturated fatty acids and has higher cholesterol rating that the egg white. Egg yolk colour depends on the diet of the chicken.
Air cell: Forms at the blunt end of the egg after it has been laid and cools down. The size of the air cell is linked to its quality: fresher eggs have smaller air cells (AA grade) and older eggs have larger air cells (A grade).
Cuticula: Also known as the bloom is a protective layer that reduced moisture loss and bacterial contamination of the egg’s contents. It is advised not to wash eggs to keep the bloom intact and increase egg storage life as well as quality.
Chicken diet and age influences yolk colour and egg size
As with most all animals, healthy hens lay eggs. Fat, sick, stressed or moulting chickens do not lay eggs. Often the weather also has an effect on egg production, for instance during autumn or spring, a sudden cold front might reduce egg production for one or two days. Very hot weather in summer, such as a heat wave, can also cause a pause in production. Chickens also lay little to no eggs in winter.
The size of the egg depends on the age and breed of chicken. Light breeds generally lay smaller eggs whereas heavy breeds lay larger eggs. When young hens start to lay; their eggs are smaller and increase in size until their first moulting (in their second year), after this the egg doesn’t really get any bigger. Also as the hens age they tend to lay fewer eggs as numbers are traded for size.
Egg sizes: Traditional scales and modern range (slight variation based on country)
Traditional Size
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Traditional Mass
(g)
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Modern Size
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Modern Mass (g)
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Size 0
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Greater than 75
|
||
Size 1
|
70-75 (2.47-2.65 oz)
|
Jumbo/King size
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70+ (2.47+ oz)
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Size 2
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65-70 (2.29-2.47)
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Extra-large (XL)
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64-70 (2.26-2.47)
|
Size 3
|
60-65 (2.11-2.29)
|
Large (L) 57-63 (2.01-2.22)
|
|
Size 4
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55-60 (1.94-2.11)
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||
Size 5
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50-55 (1.76-1.94)
|
Medium (M)
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50-56 (1.76-1.97)
|
Size 6
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45-50 (1.59-1.76)
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Small (S)
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43-49 (1.52-1.73)
|
Size 7
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Less than 45
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Pullet/Peewee
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35-42 (1.23-1.48)
|
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| Koekoek's egg is on the right and a Leghorn egg is on the left. The Leghorn egg is 53 g (1.87 oz) whereas Koekoek's is a whopping 94 g (3.32 oz)! Probably the reason why she's so cranky all the time - LOL! |
Yolk colour depends in the diet of the chicken and becomes darker (sometimes orange) when chickens are allowed to forage for plant based material and insects which contain a large portion of fat-soluble pigments, for example carotenes in plants (prominent in carrot roots). Diets based mostly on wheat result in pale yellow yolks, medium yellow yolks are a result of feed supplemented with yellow corn, dark yellow yolks result from alfalfa and insect foraging. Red, green and orange coloured yolks are a result of chicken feeding on lots of greenery or high-pigmented seeds/grains.
For maximum egg production and high quality eggs; keep your chickens well fed and limit stress. If your chickens are free range they get most of what they need through their foraging and pellets, extra protein and calcium is supplied through insects and grubs. In winter you might want to supplement their calcium and protein by feeding calcium dust (such as those you get for reptile pets) or crushed eggshells (washed & dried) and cat food/green forage respectively (cat food maximum twice a week as it has a lot of fat, green forage like alfalfa which is high in protein can be grown and fed to the chicken in winter as a healthier supplement). See my Feed and Watering Post for more dietary requirements of chickens.
Egg Glitches & Abnormalities
Sometimes eggs are speckled which can occur due to uneven calcification of the shell or uneven bloom coating. This happens when chickens start to lay again after a long period of not laying (such as moulting) or is a natural characteristic of that particular chicken’s reproductive system – so no worries about speckled eggs. Other egg glitches are wobbles or wind eggs, all of which happen occasionally and don’t indicate any health issues with your hens. However some eggs abnormalities can be an indicator of chicken health.
Problem eggs include:
Bloody shells: Sometimes occurs in new layers, but can indicate excess protein in the diet or coccidiosis infection.
Soft shells or missing shells: Usually due to a stressful event, like a big fright, chickens may lay an egg without a shell. Repeat occurrences may indicate calcium or vitamin D deficiency or disease.
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| Egg with missing shell |
Non-problem eggs:
Chalky or glassy shells: A glitch during shell formation or bloom deposits. Eggs are safe to eat.
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| Chalky shells, uneven development |
Thin shells: May occur in new layers, or during winter when additional calcium supplement through insect exoskeletons decrease. Repeat occurrence will indicate a calcium deficiency which can be easily supplemented or less often respiratory disease.
Wobbles: A formation malfunction with various results, such as highly pointed eggs or eggs with wavy/uneven surfaces, all of which occur from time-to-time.
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| Wobble egg |
Wind eggs: An egg without a yolk and contains fibrous membranes. Likely in new layers and sometimes when hens start laying after a period of moulting.
Broken eggs: Likely due to rough handling by chickens, such as scratching in the nest or sometimes eggs arrive a little bit early/late while the chickens are roosting and the unfortunate egg lands with a splash on the floor below… cracked or broken egg should rather not be eaten as particles/micro-organisms might have entered the egg.
Egg collection and storage
Eggs can generally be collected once a day, but do not let them multiply too much in the nest as this may trigger broodiness in your chickens or if one brake all would have to be destroyed for risk of salmonella infection. For coop and nest box dimensions please see my Housing & Coops Post.
Not washing eggs after collection is preferable as to not remove the bloom that protects the egg from microbial infection and keeps moisture inside, but sometimes they might be a bit dirty and you would want to wash them with water and a soft cloth to remove any dirt. Eggs are stored with the pointed side down in the refrigerator. The key to long lasting fresh eggs is to prevent moisture loss and bacterial contamination, methods include
Storage of fresh
home-produced eggs: Fresh eggs are those
processes on the day they were laid. Reference: Storey's Guide to Raising Chickens by Gail Damerow (2010).
Preservation
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Additives
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Storage time
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Refrigeration
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Yolks in water
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2 days
|
Whites in sealed jar
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4 days
|
|
Hard-cooked, shell intact
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2 weeks
|
|
Whole (raw)
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5 weeks
|
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Pickling
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6 months
|
|
Water glass (Sodium
silicate syrup)
|
1 part water glass to 10 parts boiled water, pour cooled
over fresh eggs with 5cm above eggs and refrigerate. No flavour change
|
6 months, 1oC (34oF)
|
Oiled (white
mineral oil)
|
Dip eggs in cooled heat sterilised (82oC, 180oF) 24 hours
after being laid. Keep for up to 4 months in carton, after which flavour
changes
|
7 months, -0.5oC (31oF)
|
Thermostabilised
|
Fresh eggs are heated in water to 54oC (130oF) for 15-18
minutes. So, basically super-hard boiled eggs.
|
8 months, 1oC (34oF)
|
Frozen
|
Whole (contents whisked together) or whites/yolks
separated
|
12 months, -18oC (0oF)
|
Fresh eggs can last a long time and are safe to eat a months after they were laid. The egg freshness test involves floating it in a bowl of water, fresh eggs sink and bad eggs float. We did a float test with our eggs to see whether or not we should freeze them away for the winter. This one was labelled (pic below) in early February and should have started floating upwards (at the blunt end where the air cell increases with age), but it only started floating in late June – almost 6 months later! The egg got a bit lighter and glugged when shook as the bloom was removed due to the multiple water immersions and the moisture evaporated from the inside. So you can just horde a few eggs during the summer for the winter months when egg laying is almost non-existent.
 |
| Water float egg freshness test |
Else you can freeze the eggs away in ice cubes either whole (after whisking the contents together) or by separating the whites and yellows. You can add salt or sugar to them and use for savoury or sweet preparations, respectively.
Refrigeration is the best option for long term storage, but simple cooking of methods, such as hard-cooked eggs will only keep for 2 months tops. Whereas pickling, oil, thermostabilised or frozen eggs keep far longer.
Egg excess and selling
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| Backyard chicken eggs |
If you have a lot more eggs than you can eat, you can sell the extra and will likely get enough money in return to pay for the chicken feed and general maintenance. Although you are allowed to sell your eggs, you may require a permit as per your municipal by-laws. Other requirements may include the stamping of your eggs as a symbol of origin (organic, free range) and quality.
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| Egg quality stamp |
Some sales are exempted from municipal regulations, such as door-to-door/farm shop sales or direct sales to family and friends. Please be sure to check your local municipal by-laws. I can't seem to find the regulations regarding the selling of backyard chicken eggs for South Africa. I could only find by-laws regarding the Keeping of Poultry in the Johannesburg and surrounding areas.
If all else you can hand them out to friends and family (this is seen as a gift and no regulations apply, but receivers might give you a small donation towards chicken feed J).
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