12 MASS. EXPERIMENT STATION BULLETIN 301 



Summary 



1. Two lines of Rhode Island Reds, bred for non-broodiness and broodiness 

 respectively, were carried through a nine-year period to study the nature of the 

 broody instinct and its relation to fecundity. 



2. These two lines proved to be essentially identical in age at sexual maturity, 

 winter clutch size, and annual persistency. 



?>. The non-broody line exhibited a shorter winter pause than the broofly line, 

 and also more families free from pause. 



4. The mean percentage of non-broody daughters, for the period of the ex- 

 periment, was 72.66 in the non-broody line and 20.46 in the broody line. 



5. Dams free from broodiness for three or more years gave a significantly 

 greater proportion of non-broody daughters than was obtained from dams free 

 from broodiness {^ one or two years only. 



6. The data indicate that broodiness cannot be entirely eliminated by the 

 selection of aged broody-free dams. It seems probable that the breeding test for 

 males offers the only possible solution. 



7. The two lines showed a distinct difference in degree of broodiness in broody 

 individuals as measured by the number of broody periods. The non-broody line 

 had 2.63 + .16 periods and the broody line 3. 99+. 11 periods in this experiment. 



S. Degree of broodiness is definitely inherited, as shown by the fact that daugh- 

 ters showed a rlefinite and consistent increase in degree of broodiness as the number 

 of broody periods of the dams increased. 



9. No difTercnce in mortality in the laying houses was observed in the two lines. 



10. Mean winter egg production was about twelve eggs greater per individual 

 in the non-broody line. 



11. Annual egg records were significantly higher for non-broody birds in the 

 non-broody line than for non-broody birds in the broody line. 



12. Annual egg production of broody birds in the non-broody line was greater 

 than that of broody birds in the broody line. 



13. When all birds are considered, the average annual production was 209.81^^ 

 1.67 eggs for the non-broody line as compared with 179.02 + 1.34 eggs for the 

 broody line. 



References 

 Kisher, R. A. 1930. Statistical methods for research workers. 3ded. Oliver and 



Boyd, London. 

 Goodale, H. D., Ruby Sanborn and Donald White. 1920. Broodiness in domes- 

 tic fowl. Mass. Agr. Expt. Sta. Bui. 199. 

 Hays, F. A., Ruby Sanborn and L. L. James. 1924. Correlation studies on 



winter fecundity. Mass. Agr. Expt. Sta. Bui. 220. 

 Hays, F. A., and Ruby Sanborn. 1927. Net correlations of characters concerneil 



in fecundity. Mass. Agr. Expt. Sta. Tech. Bui. 12. 

 Hays, F. A., and Ruby Sanborn. 1932 a. Types of intensity in Rhode Island 



Reds. Mass. Agr. Expt. Sta. Bui. 286. 

 Hays, F. A. 1932 b. Hereditary and environmental factors affecting variability 



in egg production. Mass. Agr. E.xpt. Sta. Bui. 289. 

 Jul], M. A. 1932. Poultry breeding. John Wiley and Sons, New York. 

 Punnett, R. C, and P. G. Bailey. 1920. Genetic studies in poultry. 



II. Inheritance of egg color and broodiness. Jour. Genetics 10:277-292. 



Publication of this Document Approved by the Commission on Administration .\nd P'inance. 

 3M-ll-'33 No. 9723 



