260 



MASS. EXPERIMENT STATION BULLETIN 258 



(1) Character of female breeders with respect to traits affecting egg production, 

 together with annual egg records, hatching records and number of offspring; 



(2) mean egg weight, hatchability of dams, complete mean weight records for 

 one year on surviving progeny, mortality in chicks to September 1, and mor- 

 taUty rate of pullets in the laying houses grouped by mothers; and (3) complete 

 record of all surviving daughters with respect to traits affecting egg production, 

 and annual egg record of each. 



It is hoped that such a presentation will enable the reader to follow the results 

 of each mating and to see at a glance why any particular mating gave the results 

 indicated. It is also a simple procedure to discover improvements or faults 

 introduced by crossing inbred lines as well as by inbreeding the check lines. 

 Complete data are given rather than summaries because such records are neces- 

 sary in studying a very complex characteristic like annual egg production. More- 

 over, genetic analyses only apply to the many individual traits affecting egg 

 production when each trait is considered as a unit for each individual of a family; 

 hence family averages or summaries are of small value as a w^orking basis. An 

 attempt is made in the comments following each table to show just why specific 

 matings or types of matings are successful or otherwise. 



Experimental Data on Effects of Heterosis 



A supplementary test to the inbreeding experiment was made to study the 

 effects of heterosis in 1923 and 1924. Six hens hatched in 1921 were used in this 

 experiment. These birds were intensely inbred to B 357 for three generations. 

 They were all mated as yearlings in the spring of 1923 to a "Standard"-bred 

 cockerel from a prominent flock. The individual records of these hens are given 

 below: 



Table 1. — Character of Inbred Hens 



The individual records of these inbred hens show that two of the six were gen- 

 etically early maturing, that all were lacking in weight, that two-thirds were non- 

 pause and one-third pause birds, only two were high in intensity, four were non- 

 broody and two broody, all were lacking in persistency, all were poor layers, only 

 one exhibited high hatchability, three medium hatchability and two low hatch- 

 ability, and that the number of offspring from each was rather limited. 



The cockerel (C 75450) to which the above hens were mated in 1923 came from 

 a flock bred strictly for "Standard" qualifications. His weight was about 11 

 pounds when the breeding season began and he was true to "Standard" require- 

 ments, except for smut in the under-color. This male came from an outside 

 source and was in no way related to the females with which he w^s mated. 



