24 MASS. EXPERIMENT STATION BULLETIN 396 



2. Rapid chick feathering was not consistently associated with greater weight 

 at sexual maturity. 



3. There was some evidence that rapid feathering in males is associated with 

 a lower mortality rate to the age of 5 months. 



4. The presence of the gene si for rapid feathering, at least in heterozygous 

 condition, in males is essential for the development of complete back feathering 

 at 8 weeks of age. 



5. Complete feathering required a longer period for development in the back 

 region than in any of the other major body regions. 



6. A dominant autosomal gene X exerts a cumulative effect with recessive 

 sex-linked gene si to produce complete feathering over the back at 8 weeks and 

 to essentially eliminate sex-dimorphism in rate of feathering. 



7. Either gene X alone in homozygous condition or gene si alone in homozygous 

 condition may produce slight back feathering in males at 8 weeks. 



8. Progress in breeding for rapid back feathering was slow when breeding males 

 were selected solely on the basis of feather development at 8 weeks of age. 



9. No relation was found between the se ^-linked gene for rapid chick feather- 

 ing and several important inherited characters affecting egg production. 



10. Results from a number of special matings indicate two procedures in select- 

 ing breeding stock that will establish gene si, the recessive sex-linked gene for 

 early tail growth, and gene X, the dominant autosomal gene for back feather- 

 ing, in a short period. 



(A) Classify all prospective breeding males and females when 10 to 12 

 days of age for gene si. 



(B) At 8 weeks of age definitely select both males and females that 

 showed gene si at 10 to 12 days and have complete back feathering 

 at 8 weeks of age. 



12. There was no indication that selective breeding for rapid back feathering 

 will produce undesirable effects from the standpoint of egg production. 



References 



Danforth, C. H. 1929. Two factors influencing feathering in chickens. 



Genetics 14:256-169. 

 Gericke, A. M. M., and C. S. Piatt. 1932. Feather development in Barred 



Plymouth Rock chicks. N. J. Agr. Expt. Sta. Bui. 543. 

 Jaap, R. G., and L. Morris. 1937. Genetic differences in eight-week weight and 



feathering. Poultry Sci. 16:44-48. 

 Kinugawa, Y. 1927. On the sex-linked inheritance of tail feathering in chicks 



and their sex-identification. Proc. Fourth World's Poultry Cong. pp. 



105-111. 

 Lloyd, E. A. 1939. Breeding for meat and egg production. Proc. Seventh 



World's Poultry Cong. pp. 483-487. 

 Martin, J. H. 1929. Rate of feather growth in Barred Plymouth Rock chicks. 



Poultry Sci. 8:167-183. 

 Radi, M. H., and D. C. Warren. 1938. Studies on the physiology and inherit- 

 ance of feathering in the growing chick. Jour. Agr. Res. 56:679-705. 

 Saharova, L. N. 1926. Genetics of the rate of feathering. Mem. Anikowo Sta. 



edited by Koltzoff p. 130. 

 Warren, D. C. 1925. Inheritance of rate of feathering in poultry. Jour. Hered. 



16:13-18. 

 Warren, D. C. 1933. Retarded feathering in the fowl. Jour. Hered. 24-431-434 



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