258 



MASS. EXPERIMENT STATION BULLETIN 258 



Inbred groups in rhis experiment represent a very narrow foundation in that 

 one hen, C 1124, and three of her daughters furnish the female ancestry. The 

 male ancestry of the inbred groups also falls into narrow limits in that the sire 

 of the three foundation daughters was used, and the other two males were related 

 to these females. Inbreeding birds from such a limited foundation should imme- 

 diately uncover weaknesses as well as desirable qualities but should not be 

 expected to have much effect on uniformity. On the other hand, where inbreed- 

 ing is practiced with birds from diverse ancestry, greater uniformity in progeny 

 should result. This last point may be studied in the check group of this experi- 

 ment when the birds were inbred from 1926 to 1928. 



Basis for Selection 



Selection of breeders each year after 1923 whenever there were surplus birds 

 to choose from was based on the following considerations: Genetic early maturity 

 (Hays 1924), high intensity, no winter pause, non-broodiness and high persist- 

 ency (Hays 1927). Selection was also made for high hatchability, low chick 

 mortality, low mortality in the laying houses, heavy body weight and large 

 families. 



Attention should be called to the fact that the five heritable traits so inti- 

 mately concerned in egg production are not measurable in males. Such circum- 

 stances add greatly to the difficulties of selecting breeding stock to improve such 

 a complex characteristic as high fecundity. The progeny test of males appears 

 the only possible method of handling this problem and such a method is far from 

 exact. 



Whenever a surplus of pullets and cockerels occurred, complete families were 

 culled on the above basis. No culling was done in any family retained, and all 

 pullets from famiUes retained were kept to finish a full laying year if theiy sur- 

 vived. Only a superior sample (from a physical standpoint) of the cockerels 

 from a family was kept after the family reached six months of age. 



Table A records the number of matings, the number with resulting progeny, 

 and the number eliminated, each year. 



Table A — Recokd op Matings and Progeny, 1923-1928 



Table A shows that during the first three years of the experiment when the 

 check birds were outbred and the inbred lines carried as such, the number of 

 matings was practically the same in each group. During the last three years 

 there were 20 check matings and 65 inbred matings. 



During the first three years 11 check matings and 15 inbred matings gave 

 progeny. There was a rapid decline in percentage of successful matings in the 

 check group. The inbred group, on the other hand, showed an increase in this 



