RAPID FEATHERING IN RHODE ISLAND REDS 17 



Mating 8 was between sires that lacked both early tail growth and back feather- 

 ing and females lacking gene si for early tail development. In the control line, 

 this mating gave 204 + to 553 — males and 241 + to 539 — females; in line 2, 

 the males were essentially all without back feathering. This difference between 

 the male progeny from the two lines was apparently traceable to the presence of 

 sex-linked gene si in heterozygous condition in some sires used in the control 

 line and its absence from sires used in line 2. 



Mating 9 was made in 1932 and 1933 between birds classified only for the tex- 

 linkedgeneat 12 days of age. This early generation produced 13 + sons to 183 — -. 

 The daughters showed the proportions of 50 + to 132 - — at 8 weeks. Back fea- 

 thering in the sons could not appear if produced by the sex-linked gene si unless 

 an inhibitor to rapid feathering such as pointed out by Warren (1933) had been 

 present in some of the dams. It seems more likely that an autosomal gene affect- 

 ing back feathering was present in a few birds. 



Mating 10 included sires pure for gene si and having back feathering at 8 weeks 

 mated to unclassified dams. A small number of such matings gave only 14 sons 

 and daughters both in the control line and in line 1. The number of matings 

 was too small to give conclusive results. 



Mating 11 was made between sires either heterozygous or homozygous for 

 gene SI for slow feathering but showing back feathering at 8 weeks and unclassi- 

 fied dams. From such matings almost all of the sons and all of the daughters 

 had back feathering, probably due to autosomal genes concerned. 



In mating 12, sires not homozygous for the sex-linked gene for rapid feather- 

 ing and lacking back feathering at 8 weeks were mated to unclassified dams. In 

 the control line one-third of the sons had back feathering, probably inherited 

 from their dams. More than half of the daughters showed back feathering. These 

 results are in marked contrast to those of mating 11 where J4 sires were used. 

 In line 2, the sons were essentially all slow in back feathering while the daughters 

 showed back feathering. 



Mating 13 should be a superior mating from the standpoint of combining 

 genes for back feathering with the sex-linked gene for rapid feathering in the sons. 

 In the control line the progeny w'ere too few to give accurate information. In Hne 

 1, however, the feathering behavior of the sons indicates the desirability of com- 

 bining sex-linked gene si with other genes affecting back feathering. The daughters 

 from these matings lacked gene si and were rather poorly feathered. 



Mating 14 need not be considered because of the very few progeny produced. 



Mating 15 shows the results from mating males with back feathering to females 

 lacking the sex-linked gene si for rapid feathering. In the control line only a small 

 percentage of both sons and daughters was feathered at 8 weeks. In line 1 this 

 type of mating gave about equal numbers of feathered and unfeathered sons and 

 daughters at the age of 8 weeks. This is in contrast with mating 13 where most 

 of the sons were feathered when they received the gene si. 



Mating 16 need not be considered because of very limited data. 



Mating 17 was an important type of mating and was used extensively. Sires 

 were selected for back feathering at 8 weeks and these were mated to the general 

 run of dams in the flock. In the control line about two-fifths of the sons had 

 back feathering while about three-eighths of the daughters were similarly classi- 

 fied. In line 1, about two-fifths of both sons and daughters were feathered. 

 These proportions suggest that the sires did not breed true for rapid back 

 feathering, which might seem to indicate a heterozygous condition for a single 

 dominant autosomal gene. 



Mating 18 may be compared with mating 17. In mating 18 the sires lacked 

 rapid back feathering. In the control line this type of mating gave one-fourth 

 of the sons with rapid back feathering and about the same proportion of daughters 



