Sex-linking is where a plumage trait, like slow feathering or a certain color pattern, is linked to the sex chromosome so that there is a distinct physical difference between the sexes of day-old chicks. This saves time and money separating the females for egg production. Today's egg producing hens can produce over 300 eggs per year; this is over twice the average of 150 eggs per year in 1947.
Egg Layers: White eggs from White Leghorn (left) background and brown eggs are usually a form of sex-linked hybrids
The primary breeders and multiplier flocks are owned by an international breeder company.
Breeders are raised in a slatted floor house with automatic watering, feeding, and egg collection systems. The slatted floors allow the birds to actively function on a floor surface while allowing the manure to fall through the slats into a manure pit. This keeps the birds and eggs cleaner.
Males and females are allowed to mate naturally. Females begin producing eggs around 20 weeks of age and will lay efficiently until about 85 weeks of age. Both white-shelled and brown-shelled egg lines are produced depending on the desired egg market. The only difference is the color of the egg shell and the breed of bird that we use to produce the egg. Brown egg birds are slightly less efficient at egg production per pound of feed than are white egg producers, mainly because the brown egg laying breeds are larger bodied and require more feed for body maintenance.
It takes a female between 23 and 32 hours to produce a fertile egg. The eggs are automatically collected daily, transported to the hatchery and stored at 55-65° F and 70% humidity until they are set in the incubator. The eggs are held here for about three to seven days prior to placing in an incubator. One fertile hatching egg is worth $.28 and weighs around 60g.
The breeder company owns a hatchery for layer chick production. Incubators hold thousands of eggs in a very controlled environment. At day 18, the eggs are transferred into hatching baskets. On the 21st day, the chicks hatch.
Once the chicks hatch, they are removed from the hatchers and processed before being taken to pullet grow-out farms. Processing of layer type chickens include sexing (separating the males and females) and vaccination. They are then counted and placed in baskets for delivery to the farm within 12-48 hours of hatch. A pullet chick is worth about $.65 to $.75 and weighs between 35-40g. The picture to the right is of hatching baskets containing brown egg laying sex-linked chicks prior processing. They are referred to as sex-link because plumage color genes are linked to the sex gene and the females are red and males are white at hatch. You should be able to determine the sex of each of these chicks.
The international layer breeding companies usually sell these chicks to layer farms that control the rest of the birds' life. Some companies specialize in raising pullets until they begin laying and then sell the started pullets to the egg farm.
The chicks are then placed in a cage or floor rearing house, depending on which environment they will be raised as adults. The pullets are raised in this facility for the first 18 weeks of life under environmentally controlled conditions. Controlling the length of daylight is extremely important for pullets. Pullets are never allowed more than 10 hours of light daily, so they are not prematurely stimulated to lay eggs. During the 18-week grow-out period, white egg pullets will eat 11.5 pounds of feed each, will grow to 3.4 lbs, and be valued at $3.50. Brown egg pullets will eat 13.2 pounds of feed each, will grow to 4.4 lbs, and be valued at $3.75. Once the birds reach 18 weeks of age, they are sold to a layer farm or transferred to the layer company's layer facility.
Once the pullets arrive at the layer house they are fed a layer ration high in calcium (egg shells require a LOT of calcium!) and given 14-16 hours of light daily to stimulate egg production. Most producers like flocks to begin laying at around 20 weeks of age. A flock of hens will lay efficiently for 60-65 weeks. White egg birds will lay 260-285 eggs a year and eat 3 pounds of feed for every dozen eggs they produce. Brown egg layers will lay 240-280 eggs a year and eat 3.5 pounds of feed for every dozen eggs they lay.
Once the hens lay for 60-65 weeks, they are rested or molted. This will force all the hens to stop laying at the same time and allow them rebuild calcium stores and restore body condition. Hens are then brought back into production together for another laying cycle. Depending on numerous economic factors, hens are kept for one to three laying cycles before they are replaced with a new flock. Hens lay for a shorter time and lay poorer quality eggs in each subsequent cycle, but eggs are usually a bit larger as hens age.
Egg Collection and Marketing
Eggs are automatically collected daily on belts and rollers into an egg processing room connected to the hen houses. In the processing room, machines wash, grade, and sort the eggs by size and package the eggs for the whole egg market or to be shipped to a further processing plant. Some modern egg breaking plants do not carton the eggs but break them into liquid eggs for pasteurizing inline.
Consumer carton eggs are shipped to the store within four days of collection.
Further Processed Products
Further processing changes the product into something more convenient or useful in another form. Liquid and dried eggs are used in a wide array of consumer products. Convenient pre-cooked egg products are also more common at food stores and restaurants. This also adds more value to the final product.