PRODUCTION Prior to World War II, most egg production came from farm flocks of less than 400 hens. By the early 1960's, improved technology and the development of sophisticated mechanical equipment were responsible for a shift from small farm flocks to larger commercial operations. In the major egg producing states, flocks of 100,000 laying hens are not unusual and some flocks number more than 1 million. Each of the 235 million laying birds in the U.S. produces from 250 to 300 eggs a year.

FACTORS THAT INFLUENCE EGG PRODUCTION

Genetic pattern of the breed of hen. Maximum production of top-quality eggs starts with a closely controlled breeding program emphasizing favorable genetic factors. The Single Comb White Leghorn hen dominates today's egg industry. This breed reaches maturity early, utilizes its feed efficientIy, has a relatively small hody size, adapts well to different climates and produces a relatively large number of white-shelled eggs, the color preferred by most consumers. Because brown-shelled eggs are favored in the New England region, the Rhode Island Red, New Hampshire and Plymouth Rock breeds predominate in that area of the country. -see Color

Hen's age at egg-laying maturity. Although early starters lay more eggs, maturity too early results in many small eggs.

Resistance to disease. Selective breeding is reinforced by good sanitation and vaccination.

Light control. Of primary importance both during the growing and laying periods, controlled, low-intensity light can be used to delay sexual maturity until the bird's body is big enough to produce larger eggs. Today's laying hen doesn't need to depend upon the fickle sun to tell her when laying time has arrived. Intensity and duration of light can be adjusted to regulate production.

Quality of feed. Since more is known about the nutritional requirements of the chicken than of any other domestic animal, it is not surprising that rations are scientifically balanced to assure layer health along with optimum quality eggs at least cost.

Temperature. Laying houses maintained between 57 and 79 degrees F. (14 and 26 degrees C.) are desirable.

Humidity. A relative humidity between 40 and 60% is best.

Replacing or molting the flock. Molting, or loss of feathers, is a natural occurrence common to all birds regardless of species. As the hen ages, egg quality declines and at about 18 to 20 months of age, molting occurs and egg production ceases. While some flocks are sold for slaughter at this point, replacement is costly. A fairIy common practice is to place the flock into a controlled molt. After a rest period of 4 to 8 weeks. the birds start producing again. Poultrymen have found that with two periods of controlled molting, one at 14 months of age and another at 22 months, egg quality is more consistent than with one molt at 18 or 20 months.

The laying house. In today's egg-laying facilities, temperature, humidity and light are all controlled and the air is kept circulated. The building is well insulated. windowless (to aid light control) and is force-ventiiated. Birds are either given the run of the floor area or are housed in cages. Most new construction favors the cage system because of its sanitation and efficiency, but floor operations are also in use.

Feeding. Because care and feeding of hens, maintenance, sanitation and egg gathering all take time and money, there is a strong trend toward automation whenever possible.

Automatic feeders, activated by a time clock, move mash through troughs in the floor or past the cages. Birds at floor level drink from troughs. Those in cages may sip from such sophisticated accessories as self-cleaning drinking cups or nipple valves.

Most poultry rations are of the all-mash type. They are made of sorghum grains, corn, cottonseed meal or soybean oil meal depending upon the part of the country in which the ration is produced and which ingredient is most available. The feed is carefully balanced so that the hen gets just the right amounts of protein, fat, carbohydrates, vitamins and minerals. Today's hen eats a better balanced diet than many people!

The hen's ration may contain the same types of additives approved for human food. Antioxidants or mold inhibitors (also used in mayonnaise and bread) are added to maintain the quality of the feed. And, like people, chickens occasionally require an antibiotic.

An additive is not approved for use in poultry feed unless adequate research has been undertaken to determine its pharmacological properties and possible toxicity and to discover any potentially harmful effects on animals.

Hormones are not fed to poultry in the United States.

How much a hen eats depends upon the hen's size, the rate of egg production, temperature in the laying house and the energy level of the feed. In general, about 4 pounds of feed are required to produce a dozen eggs. A Leghorn chicken eats about 1/4 pound of feed per day, Brown-egg layers are slightly larger and require more food.

Egg quality is affected by the type of feed. Shell strength, for example, is determined by the presence and amounts of vitamin D, calcium and other minerals in the feed. Too little vitamin A can result in blood spots. Yolk color is influenced by pigments in the feed. Maximum egg size requires an adequate amount of protein and essential fatty acids.

Handling. The moment an egg is laid, physical and chemical changes begin to conspire against freshness. Warm temperatures encourage those changes, so newly laid eggs must be gathered frequently and refrigerated quickly.

Some eggs are still gathered by hand, but in most production facilities automated gathering belts do the job. Gathered eggs are moved into refrigerated holding rooms where temperatures are maintained between 40 and 45 degrees F. (5 and 7 degrees C.). Humidity is relatively high to minimize moisture loss but should not exceed 80%. Sometimes eggs are oiled as they are gathered.

Processing and distribution. Some producers sell their eggs nest run (ungraded) to processing firms which clean, grade, size and carton the eggs and ship them off to retail outlets. Other farms and ranches carry out the entire operation. -see Egg Products, Egg Products Inspection Act, Grading, Nest Run