BULLETI]^ Ilo. 199. 



DEPARTMENT OF POULTRY HUSBANDRY. 



BROODINESS IN DOMESTIC FOWL. 



DATA CONCERNING ITS INHERITANCE IN THE RHODE 

 ISLAND RED BREED. 



BY n. D. GOODALE, RUBY SANBORN AND DONALD "UTIITE. 



Introduction, 



Broodiness, as pointed out by Herrick (1907a, 1907b), is one phase of 

 a recurring cyclical process in birds. In the domestic fowl when kept prima- 

 rily for egg production, the instinct is not allowed to run its normal course, 

 but is checked b}^ suitable means in its initial objective stages. Some 

 indi\aduals, however, never exhibit the instinct. In this study of the 

 inheritance of broodiness two categories of birds may be recognized, viz., 

 those that exhibit the initial stages of broodiness, which are promptly 

 checked, and those that do not exhibit any signs of broodiness. Broodi- 

 ness is intimately connected with egg production, and, other factors being 

 equal, its presence or absence determines the number of eggs laid, since, 

 as sho^Ti later, its presence tends towards decreased production. A knowl- 

 edge of its inheritance should show the steps necessary for its complete 

 elimination from a flock. 



The character, moreover, is not a superficial and unimportant one, but 

 is a well-defined characteristic of the class Aves, and is essential for the 

 sui-vival of every species in the class. If the instinct were lost in a state 

 of nature, without being replaced by some compensating mechanism, ' 

 the race would become extinct. In nature selection is constantly directed 

 in favor of the character, since those individuals that lack it will leave no 

 progeny, yet among domestic fowl we find entire races in which the charac- 

 ter is lacking. 



Poultrymen recognize both broody and non-broody races. The American 

 breeds, i.e., Plymouth Rocks, Rhode Island Reds and W.yandottes, and 



" It is well known, of course, that the American cowbird and the European cuckoo have devel- 

 oped a compensating mechanism. 



