NON-BROODY AND INTENSE BROODY LINES 5 



The proportion of pause and non-pause birds shown by the detailed data was 

 1 non-pause to 1.72 pause birds in the non-broody line compared with 1 non-pause 

 to 1.91 pause birds in the broody line. There were four families in the non-broody 

 line in which no daughters with pause occurred and only one family in the broody 

 line that showed no pause daughters. Contrary to earlier observations, the effect 

 of breeding for non-broodiness in this experiment has been to reduce winter pause 

 duration. 



4. Annual Persistency 



Annual persistency is arbitrarily terminated with 365 daj's as a maximum. In 

 those birds which stopped laying for 30 days or more after March first but before 

 the close of their 365-day laying year, persistency was less than 365 days. High 

 persistency is the most important of all inherited characters in relation to annual 

 production, according to Hays and Sanborn (1927, loc. cit.). The net correlation 

 between persistency and annual egg production in Rhode Island Reds is +.7501 + 

 .0063. It is important, therefore, to discover possible relations between broodi- 

 ness or non-broodiness and persistency of laying. 



Although the non-broody line showed higher average persistency than the 

 broody line in seven of the nine experimental years, the differences in the two lines 

 were found to be of questionable significance when tested by Fisher's method for 

 determining the significance of differences in a series of means. It is probable, 

 therefore, that the two lines are essentially alike in persistency. 



Table 4. Annual Persistency in Non-Broody and Broody Lines. 



5. Absence of Broodiness in the Pullet Year 



The results of selection for freedom from broodiness in one line and for intense 

 broodiness in another line are summarized in Table 5. 



In the non-broody line the proportion of non-broody birds varied from about 60 

 to 92 per cent : in the broody line the proportion ranged from about 4 to 50 per cent. 

 The detailed data show that no non-broody families were obtained in the broody 

 line, e.xcept in 1923 when 40 per cent of the families were entirely non-broody. 

 In the non-broody line the percentage of non-broody families ranged from 28.6 to 

 66.7 with a mean of about 50. The data do not show progress either in eliminating 

 broodiness or intensifying broodiness in the nine-year period. 



There are three possible reasons for failure to make progress: (1) Small numbers 

 of birds were used; (2) breeding pens were made up in part of genetically untested 

 pullets and cockerels; and (3) there was no phenotypical record on the males. 



