6 MASS. EXPERIMENT STATION BULLETIN 301 



The first two (litViciilties may be easily met, but the progeny test offers the only 

 partial solution of the third difficulty. 



These data as well as other records of the Station flock indicate that broodi- 

 ness is a trait which it is very difficult to eliminate completely. As pointed out 

 elsewhere, a female should not be (Massed as non-broody because she does not be- 

 come broody during her first or second laying year; for it is not uncommon for 

 broodiness to manifest itself during the third laying year or even later. Trap- 

 nesting may also tend to discourage the instinct in some individuals. In order to 

 eliminate this character in any line of birds, it would at least be necessary to trap- 

 nest all female breeders throughout their productive life and to select male breeders 

 entirely on the progeny test after all daughters have completed at least two laying 

 years. Such a breeding scheme is expensive and is of questionable economic value. 



Table 5. Birds Non- Broody in the Pullet Year. 



Non- Broody Line Broody Line 



Total Non-Broody Birds Total Non-Broody Birds 

 Number Number 



of Birds Number Percent of Birds Number Percent 



1923 14 



1924 5 



1925 60 



1926 12 



1927 26 



1928 40 



1929 33 



1930 33 



1931 44 



Total 



or 267 194 72.66 259 53 

 Mean 



6. Age at Onset of Broodiness 



A number of workers have pointed out the fact that the broody instinct may not 

 appear during the first laying year and yet may appear in later years with con- 

 siderable intensity. Goodale et al. (1920, loc. cit.) have shown that broodiness 

 appears earlier in the first laying year in more intensely broody lines. On the sam.e 

 basis it might be assumed that deferred broodiness may be associated with low 

 degree of broodiness. Management may be a factor in deferred broodiness, as 

 Punnett and Bailey (1920) indicate. 



In Table 6 the non-broody line alone is studied. The table includes the per- 

 centage of non-broody daughters (pullet-year record) from dams free of broodiness 

 during their first laying year only; from dams free of broodiness for two laying 

 years but exhibiting the trait in the third or later years; and from dams never 

 observed to be broody in three or more laying years. Such a tabulation considers 

 the phenotypical behavior of the dams only and gives no consideration to the male 

 ancestry. The phenotypical nature of the daughters is reported for the pullet lay- 

 ing year alone, which does not correctly classify a considerable proportion. The 

 data do show, however, in a general way the relative eftectiveness of breeding 

 from females with different degrees of deferred broodiness and from apparently 

 non-broody individuals in developing a line free of broodiness in the pullet year. 



