to the species of the fowl and variety. The number of eggs which a chicken will lay varies greatly. Attempts have been made, with great success, at experiment stations, to develop chickens with high laying powers. A hen which will produce over 200 eggs a year is regarded as a high-grade fowl for egg-producing purposes. Eggs are produced more abundantly during the early spring and summer than during the winter months. One of the purposes of scientific egg producing is the development of fowls that will produce eggs more evenly throughout the whole year, thus avoiding the very great depression in the price of eggs in the spring and the excessively high price of eggs in the winter.
Composition of Eggs.—A large number of eggs have been analyzed in all quarters of the world and found to vary but little in composition in different localities, and very little also in regard to the variety of the fowl. The egg consists essentially of two portions,—an external highly albuminous portion known as the white and an internal colored portion, yellow or reddish in tint, known as the yolk. The white of an egg is composed almost entirely of albumin partially dissolved in water. The yolk of the egg is composed of albumin, fat, and a phosphorus-bearing material of high nutritive value known as lecithin. The yolk of an egg is a much richer food product than the white, containing in addition to the nitrogeneous element the fat and mineral bodies necessary to nutrition. Both the white and yolk of an egg are composed principally of water as will be seen by the following analytical data:
COMPOSITION OF EDIBLE PART OF EGGS.
Water. Protein Fat. Ash. Calories.
Percent. Percent. Percent. Percent. Per pound.
Hen, 73.7 13.4 10.5 1.0 . . . .
Duck, 70.5 13.3 14.5 1.0 985
Goose, 69.5 13.8 14.4 1.0 985
Turkey, 73.3 13.4 11.2 0.9 850
Preservation of Eggs.—Freshly laid eggs may be preserved for several days without any notable deterioration by keeping in a cool place. The temperature of preservation should be as nearly the freezing point as can be secured. The vital processes are continually going on in a fresh egg and hence there is a development of a certain degree of heat due to these activities. For this reason eggs can be placed in an atmosphere below the freezing point of water without being frozen. An additional reason for this is found in the fact that the water which is present in eggs holds the albumin and other bodies in solution and the freezing point of a solution is always lower than that of the solvent alone. For domestic purposes where refrigerating establishments are not available the fresh eggs should be kept in a cool dark place where the temperature is not allowed to go above 50 or 60 degrees. At a higher temperature than this fresh eggs lose their freshness in a remarkably short time. The porous nature of the shell is a condition which favors the deterioration of the egg by the admission of air and microbes into the substance of the egg itself.
