44 MASS. EXPERIMENT STATION BULLETIN 215. 



tion seems to bear a closer relation to the breeding of her sire than to the production 

 of her dam. 



Dryden, '21, reporting on eight generations of Barred Rocks, eight generations of 

 Leghorns and eight generations of Cross-breds, states that some hens and some 

 males have the power of transmitting high fecundity; others have not this power. 

 He advises the progeny test as the most reliable method of selecting breeders. 



Hurst, '21, in his work in breeding White Leghorns and Wyandottes, found no 

 sex linkage in the inheritance of factors for egg production. In other words, he 

 agrees with Goodale and Diyden in his assumption that both parents contribute 

 ecjually in factors for egg production. 



Other authorities rather generally agree with one or the other of the above 

 schools, so that it seems safe to assume that egg production is transmitted in 

 Mendelian fashion from parent to olTspring. A discussion of the several proposed 

 genetic theories is not within the province of this report. Whether or not factors 

 for egg production are transmitted in the same fashion in all breeds requires further 

 study. This report is intended to throw some light on the expected progress in 

 mass breeding without considering definite Mendelian factors as operating to con- 

 trol the egg production of the flock. 



Review of Progress in the Flock. 



The data upon which this report is based cover ten years' work at the Massa- 

 chusetts Agricultural Experiment Station in breeding Rhode Island Red fowls 

 primarily for egg production. The foundation flock of 100 pullets and eggs from 

 which 50 more were hatched were purchased in the fall of 1912 from a Ma.ssachu- 

 setts breeder. These were good representatives of the breed, judged by the breed 

 standards of that time. This foundation female stock was placed in the laying 

 houses December, 1912, and all females in the experiment have since been trap- 

 nested at all times unless ph5^sically incapacitated. All annual records cover 365 

 days and were made during the pullet year. Complete pedigrees of all breeding 

 stock have been maintained throughout the period. The foundation males used 

 consisted of twelve birds brought in in the spring of 1913, four from different 

 breeders brought in in 1914, and ten from other outside sources brought in in 

 1915. Since 1915 no outside stock has been used in the flock. 



Dr. Goodale has already given the question of egg production much study and 

 m.ade several reports on the egg-laying flock up to the end of the laying year 1921. 

 His reports include a rather complete study on earh^ maturity, rate and winter 

 pause (Goodale, '18, '19). He has also carefully investigated the question of 

 broodiness (Goodale, '20). This paper deals only with the application of methods 

 for selecting breeding males, from data secured up to the end of 1922. 



The a-^-erage production of the flock b}^ j'ears is presented graphically in Chart I. 

 All pullets that had an opportunity to lay for 364 days after their first egg are 

 included. The birds are divided into six classes for study, and the percentage in 

 each class is presented by years to .show the general trend of the flock. 



The total number of annual records at the close of 1922 was 1,945. The observa- 

 tion may be made that the mode (most common class) of the foundation stock 

 lies between 100 and 149. Chart I further shows that the mode of the flock remained 

 between 100 and 149 eggs until the 1917 pullets finished their year in the fall of 

 191S. This fact does not signify a lack of progress in increasing the egg production 

 of the flock between 1913 and 1918. There was a total increase during this period 

 up to the end of the laying year ending in 1918 amounting to an average of 12.97 

 eggs per hen. The graph for the hatching year 1913 would seem to indicate a 

 higher degree of production in tlie flock as a whole than could be maintained in the 

 flocks hatched in 1914 am! '915. This is only an apparent discrepancy, however, 

 as explained by the fact that only about half the available flock hatched in 1913 

 could be trap-nested to the end of their laying year. The half selected represented 

 those having the highest record for the first half of their j'ear and consequently are 

 a select group. 



The distribution of the flock will be seen to remain almost the same for the birds 



