420 



COMMERCIAL POULTRY RAISING 



greater than from any other source, especially if male birds are 

 allowed to run with the hens. 



Heat in connection with eggs does not necessarily mean ex- 

 cessive heat, which we know will injure the quality of eggs. The 

 fertile egg is susceptible to even a moderate temperature. If 

 allowed to remain in a temperature of 70 degrees F. for any 

 length of time, it starts to incubate, slowly, of course, neverthe- 

 less development goes on, and every day it is exposed to this 

 warmth it is hastened on its downward career. The first stage 



of this deterioration ap- 

 pears as blood on the 

 yolk. Later a blood ring 

 is formed, which indi- 

 cates that the embryo is 

 dead, and like all dead 

 animal matter forthwith 

 it starts to decay. Com- 

 mercially, heated eggs are 

 known as floaters and 

 ilood rings. Light floats 

 correspond to about 

 twenty-four hours' in- 

 cubation at a temper- 

 ature of 102 degrees, 

 whereas heavy floats are equal to about forty-eight hours' incu- 

 bation. 



Infertile eggs, sometimes called sterile eggs, those laid by hens 

 kept apart from male birds, withstand heat much better than 

 fertile eggs, though it is an utter fallacy to assume that the 

 former will not spoil. This mistaken notion is all too common. 

 Without a vitalized life germ, there is no incubation in sterile 

 eggs, hence there are no blood rings to develop; nevertheless 

 they undergo certain chemical and physical changes which sooner 

 or later impair the quality of their contents. They shrink as 

 badly as the fertile eggs, and the yolks are likely to weaken and 

 break or fetick to the shells. 



Fig. 271 . — Stolen nest in the hollow of a tree. 



