INHERITANCE OF BROODINESS IN RHODE ISLAND REDS 



By F. A. Hays, 



Research Professor of Poultry Husbandry 



INTRODUCTION 



The l)r()0(ly instinct is a normal inherited character in domestic chickens. 

 This character was partially eliminated in the Mediterranean breeds dur- 

 ing the last half of the nineteenth century so that they were considered to 

 be nun-sitters. The general purpose breeds and Asiatic breeds were al- 

 most universally broody at that time. Publislied data on the percentasie 

 of broodiness in different breeds are limited. 



Kirkpatrick and Card (1917) reported that 13.6 percent of the White 

 Leghorns in the fifth Storrs Egg Laying Contest became broody. Goodale, 

 Sanborn and White (1920) pointed out that the foundation stock of the 

 ^Massachusetts .Station Riiode Lsland Reds was 89.6 percent broody; after 

 five years of breeding, tiie percentage of broody birds was reduced to 

 18.9. Hurst (1925) reported 4.8 percent of the birds broody in a flock of 

 84 Wiiite Leghorns. Hays and Sanborn (1926) reported 27.35 percent 

 broody birds in Rhode Island Red flocks averaging 200 eggs, and the 

 number of broody periods fell to a mean of less than two. Hays (1933) 

 attempted to develop a non-liroody and an intense-broody line of Rhode 

 Island Reds. After nine generations of breeding, the lines showed 72.66 

 percent and 20.46 percent, respectively, of the females non-broody in the 

 first laying year. In a high fecundity line, Hays (1939) reported a de- 

 crease in the incidence of broodiness from 86.31 percent in 1916 to 2.16 

 percent in 1937. 



The mode of inheritance of broodiness is somewhat controversial at 

 present. Punnett and Haily (1920), Goodale, Sanborn and White (1920), 

 Hays (1923), and Warren (1930) all present data to indicate that the 

 broody instinct is inherited on the basis of dominant autosomal factors. 

 On the other hand, Roberts and Card (1933) observed that reciprocal 

 matings between White Leghorns and Dark Cornish indicated that a 

 sex-linked gene was in\cil\e(l. it is possible that, in the crosses used by 

 Roberts and Card, tiie use of White Leghorn sires may have deferred the 

 onset of broodiness in a large lu/rcentagc of the li\brid daughters to the 



