jQ TECHNICAL BULLETIN 7 



Work Already Done. 

 Btf Other Investigators. 



Bateson (1902) and Hurst (1905) both present data on crosses l)etwcen 

 l)roody and non-broody races, indicating that l)roodiness is a doniinant ciiar- 

 acter. No further information was obtained at that time. 



Punnett and Bailey (1920) report some results using Black Laiigshans, 

 Brown Leghorns and Gold-pencilled Hamburgs. Results: 



Langshan 2 x Leghorn $ gave all F,* pullets broody. Of tlie F.* genera- 

 tion 16 pullets were retained, 8 of which went broody as pullets. Punnett 

 states that if the Langshans were of composition AABB and Leghorns aabb, 

 F_. should give 9 broody to 7 non-broody, a close approximation to actual ratio. 

 Tiie reciprocal cross, Leghorn $ x Langshan $ gave all broody in F„ but in 

 F. there were but 19 broody to 47 non-broody. Most of tliese birds were re- 

 tained but one year. A few that were kept the second year added more 

 broodiness so that the ratio is not 9 to 7, probably because of delayed appear- 

 ance of broodiness. 



In the Hamburg-Langshan cross, the Fj hens were either non-broody or 

 showed very little broodiness. Of 38 F, pullets, 4 were broody, 34 non-broody. 

 These results suggest a third factor, N, which inhibits. F, birds would l)e 

 NnAaCc, but factor N did not inhibit in all cases. The F, ratio gave 4 

 broody to 34 non-broody. Punnett states that his results are far from con- 

 clusive as to the true nature of the broody trait. 



Pearl (1914) found much less broodiness in Barred Pl_\nnouth Rocks than 

 exists in Reds. His method of measuring the intensity of broodiness was by 

 tlie length of non-productive period. Other known factors, such as winter 

 pause and molt make such a measure subject to error. 



]Vork Done bt/ the Massachusetts Station. 



Goodale began the study of this trait in 1912. From that time up to 1921, 

 when he severed his connections with the Station, very satisfactory progress 

 was made in eliminating the tendency from the egg-laying strain of Rhode 

 Island Reds t 



Recent Work at the Massachusetts Agricultural Experiment Station. 



In the fall of 1922 the writer took up this project using the same general 

 ])lan with some modifications. Tiie non-broody strain has been carried along 

 with the intense broody strain and not as a part of the general flock in so 

 far as the rnatings are concerned. The non-l)roody birds are now being carried 

 along through the second and third laying years to definitely test their Ic- 

 havior witli regard to broodiness. Similarly, llie breeding males arc being 

 carried over and tested for genetic composition. In a paper entitled, "In- 

 l)reeding the Rhode Island Red Fowl with Special Reference to Winter Egg 

 Production," the broody trait has been shown to confirm Goodale's AC tlicory 

 which suggests that broodiness is due to the presence of two dominant, auto- 

 somal, complementary genes, A and C. Both must be ])resent to i)roducc 

 broodiness, but either may' be carried alone by non-broody birds. 



* Fi and P2 refer to generations one and two. 

 t See Mass. Agri. Expt. Sta. Bulls. 199 and 211. 



