PRAIRIE FARMER'S POULTRY BOOK 



might affect the eggs. The remedy is to find the guilty hens 

 and dispose of them. 



Incubation 



4 



Incubation is the development of the embryo within the 

 egg, and is to be distinguished from fertilization, which is the 

 fusion of the sperm and germ cells. The period of incubation 

 is 21 days, though it may range from 18 to 24 days, depending 

 on the time occupied in supplying the required number of heat 

 units. If the temperature is run at too high a degree, the time 

 of hatching is hastened; if at too low a degree, it is delayed. 

 The normal temperature for incubation is 103° Fahr. Any 

 drop below 90° or rise above 107° is considered dangerous 

 to the hatch. The low temperature is least objectionable. 



Eggs will sometimes hatch if allowed to cool for 24 hours 

 in a room of moderate temperature, but such treatment un- 

 doubtedly results in weakened vitality. An excess of heat is 

 more disastrous because it coagulates the albumen and hardens 

 the yolk before it is absorbed into the body of the chick, causes 

 the chicks to stick to the shell in hatching, causes many chicks 

 to die in the shell, and produces a batch of weaklings that will 

 never thrive. 



Room Temperature for Eggs 



As an egg will incubate if kept in a room for any consider- 

 able time at a temperature of 70° Fahr. and as the germ will be 

 injured or destroyed if allowed to go below 30°, it is important 

 to know just how to regulate the temperature for eggs intended 

 for incubation. The correct room temperature is 60° Fahr., 

 though a range of five degrees above or below this point will 

 do no harm. A temperature of 50° Fahr. is correct for market 

 eggs. 



Size and Weight of Eggs 



The standard weight of a dozen market eggs is 24 ounces, 

 and such eggs are of average size. Abnormally large eggs 

 usually have a double yolk. An abnormally small egg may be 

 the first egg of a pullet or the last egg of a cycle, or clutch. 

 When very small, it is devoid of yolk. Eggs vary in weight, 

 even though of the same size, due to the density of the egg 

 contents. The size and weight of an egg are determined to 

 some extent by the breed producing it. 



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