RAPID FEATHERING IN RHODE ISLAND REDS 3 



Radi and Warren (1938) presented rather extensive data on chick feathering 

 in Rhode Island Reds. They reported that thyroxine injections definitely stim- 

 ulated feather development; that brooding under either high humidity or low 

 temperature improved feathering; that selection was efTective in producing strains 

 genetically different in degree of feathering at seven weeks; that superior feather- 

 ing was incompletely dominant to poor feathering but the number of genes in- 

 volved was not determined; and concluded that the genetic differences established 

 were probably due to modifying factors acting upon the sex-linked dominant 

 late-feathering gene for which the birds were known to be homozygous. 



Lloyd (1939) made a study of feathering in Barred Plymouth Rocks, Rhode 

 Island Reds, Cambars, and White Leghorns. He observed varying degrees of 

 feathering at 4, 6, and 8 weeks of age and expressed the opinion that it is probably 

 possible to produce uniform rapid feathering in Reds and Rocks. He believes 

 that rapid feathering behaves as a dominant in inheritance. 



At the present time there is considerable confusion regarding the mode of 

 inheritance of rate of chick feathering. There is general agreement, however, 

 that the general purpose breeds are normally slow in feathering and that there 

 is a sexual dimorphism in rate of feathering. Through selective breeding in 

 recent years considerable progress has been made in establishing rapid chick 

 feathering in many flocks but the problem is not a simple one. A study of several 

 phases of the problem should add important information. 



Data Available 



Beginning in 1931 all birds were classified at 12 days of age for the sex-linked 

 early feathered type only, and a study was begun at the Massachusetts Station 

 in 1933 on the mode of inheritance of rate of chick feathering in Rhode Island 

 Reds. The primary objective was to develop a method of breeding to produce 

 complete back feathering at 8 weeks of age. Ten generations of chicks have 

 been examined for back feathering at 8 weeks making a total of over 30,000 

 examinations. 



In 1934 selective breeding was begun to develop three lines with respect to 

 chick feathering. Line 1 was bred for complete back feathering at 8 weeks. 

 Line 2 was bred for absence of back feathering at 8 weeks. A control line included 

 birds bred for high fecundity without regard to rate of feathering. 



Throughout the experiment there was considerable difficulty in separating 

 pullets at 8 weeks of age into rapid and slow types with respect to back feather- 

 ing. In males no difficulty was experienced. Line 1 was always reproduced by 

 sires that had complete back feathering at 8 weeks and line 2 was always repro- 

 duced by sires that had no back feathering at 8 weeks. After the first generation, 

 female breeders were selected within their respective lines. 



Records were also secured on many of the chicks at 10 days to discover the 

 presence of the recessive sex-linked gene by the development of tail feathers. 

 Rate of feathering in nine feather tracts was studied weekly in a number of 

 chicks. Complete trapnest records were secured on many females to study the 

 relation between rate of feathering and fecundity characters. 



Character of the Foundation Stock 



A preliminary study was made on the flock hatched in 1933 to get information 

 on the presence or absence of the sex-linked gene for rapid feathering and the 

 presence or absence of back feathering at 8 weeks of age. The presence of a 

 tail at 12 days of age is produced by the recessive sex-linked gene si. Males with 

 tails were therefore marked slsl and males without tails were marked SI. In a 

 similar manner females with tails were si and those without tails were SI. At 8 



