RAPID FEATHERING IN RHODE ISLAND REDS 9 



Mating 1 was between parents both geneticalh' pure for the sex-linked recessive 

 gene si, and the sires were + for back feathering. In the control line this mating 

 gave 25 + to 5 — sons and 31 + to 16 — daughters. In line 1 all sons and all 

 daughters showed back feathering at 8 weeks. 



Mating 2 included Sisl and SlSl sires mated to si dams. In the control line 

 equal numbers of feathered and non-feathered cockerels appeared. The daugh- 

 ters showed equal numbers also. In line 1 there were twice as many + as — 

 sons and the proportions of daughters were the same as for the sons. 



Mating 3 differed from mating 1 only in that the sires used lacked back feather- 

 ing. The number of progeny- was very small but only 1 out of 12 sons had back 

 feathering. The daughters all lacked back feathering. Here is further evidence 

 of autosomal genes affecting back feathering. 



Mating 4 may be compared with mating 2 for genes influencing back feather- 

 ing. The data definitely indicate the same proportions of -f and — daughters 

 from both matings 4 and 2 in the control line. In line 2, however, essentially all 

 of the sons lacked back feathering at 8 weeks, while the daughters showed 1 + 

 to 8 — . Very likely most of the sires used in the control line were heterozygous 

 for gene si, while in line 2 the sires must have been SlSl. 



In mating 5 the dams lacked the sex-linked gene si for rapid feathering. When 

 these were mated to sires pure for the sex-linked gene si and also carrying rapid 

 back feathering, equal numbers of -}- and — sons appeared; while if the sex- 

 linked gene si were alone responsible for back feathering, there should be no sons 

 with back feathering. If the sires used in this mating carried a dominant auto- 

 somal gene X for rapid back feathering that the dams lacked, equal proportions 

 of + and — sons and daughters would result. This type of mating m line 1 gave 

 41 + to ] 2 — sons or about 3 to 1. In the daughters the proportions were about 

 5 to 1. In this line both sires and dams may have been heterozygous for gene 

 X which would give a 3 to 1 ratio. The excess of + females may have been due 

 to faulty classification for back feathering. 



Mating 6 was between sires that were either heterozygous for gene si or lacked 

 this gene entirely and were -f for back feathering and dams that lacked gene si. 

 In the control line this type of mating gave equal numbers of + and — malts 

 and females. Very likely the sires were heterozygous for gene X and the dams 

 lacked gene X. In line 1 the proportion of + and — sons was about 1 to 2 and 

 the daughters showed proportions of 3 to 2. It is probable that some sires in 

 line 1 lacked gene X. 



Legends for Plates 



Plate I. Chicks at 12 Days of Age. 



1. Presence of gene si — Female W2808 from line 1. 



2. Absence of gene si — Male W3148 from line 1. 



3. Presence of gene si — Female W2809 from line 1 male on line 2 female. 



4. Heterozygous for gene si — Male W310,5 from line 1 male on line 2 female. 



5. Absence of gene si — Female W2796 from line 2. 



6. Absence of gene si — Female W3126 from line 2 male on line 1 female. 



Plate II. Chicks at 4 Weeks of Age. 



1. Grade SI 2 — Male W3148 from line 1. 



2. Grade si 3 — Female W3116 from line 1. 



3. Grade SI — • Male W3I05 from ine 1 male on line 2 female. 



4. Grade si 3 — Female W3104 from line 1 male on line 2 female, sister to No. 3. 



5. Grade si — Female W2797 from line 2. 



6. Grade SI — Female W3199 from line 2 male on line 1 female. 



Plate III. Chicks at 8 Weeks of Age. 



1. Grade SI 3 — Male W1037 from line 1. His dam evidently carried an inhibitor of sl gene. 



2. Grade sl 3 — Male W1070 from line 1. 



3. Grade SI 3, carries gene sl — Male W1140 from line 1 male on line 2 female. 



4. Grade sl 3 — Male W1123 from line 1 male on line 2 female. 

 .5. Grade Sl — Male W823 from line 2. 



6. Grade Sl — Male W947 from line 2 male on line 1 female. 



7 . Grade SI 2 — Male W1094 from hne 2 male on line 1 female. 



