INCUBATION 83 



INCUBATION 



NATURAL INCUBATION 



In poultry, the reproductive process is accomplished 

 in two stages. The egg is first produced, developed, 

 fertilized within the body of the hen, and laid. Then 

 the egg is subjected to a certain temperature (100 F. 

 or a little higher) for about 21 da., during which time the 

 embryo develops and hatches out of the shell as a 

 chick. The process of developing the embryo within 

 the egg by means of heat is called incubation. When 

 this is carried on by a hen, it is known as natural 

 incubation; when incubation is accomplished by means 

 of a machine, oven, or other device, it is known as 

 artificial incubation. Man has little control over the 

 reproductive process in its first stage except insofar 

 as the selection of the breeders is concerned; in the 

 second stage, however, if artificial incubation is prac- 

 ticed, he can, by his methods of conducting the process, 

 greatly influence the development and future well-being 

 of the chick. 



Fertilization of the Egg. In order that eggs shall 

 hatch, the hen that lays them must have been mated 

 with the male. The actual fertilization of the egg 

 probably takes place as the yolk enters the oviduct. 

 In the process of fertilization the germ from the male 

 comes in contact with the germ cell, or blastoderm, and 

 causes it to develop, provided that it is exposed to 

 the right temperature. Hatchable eggs are those that 

 are fertilized and have vitality enough to insure the 

 production of a living chick. 



Eggs are usually fertile up to and including those 

 laid the ninth day after the hens are separated from 

 the males, and fertilization is impossible after the 

 sexes have been separated for 12 da. or more. Eggs 

 may safely be counted as fertile after the ma.les have 

 been with the hens for 9 da. or more. 



