INBREEDING IN RELATION TO EGG PRODUCTION 293 



Table 21 supplies the daughters' records up to March 1, 1929. Only those 

 daughters with complete records to this date are included in the table. 



In the age at first egg there were 56 early-maturing and 7 late-maturing inbred 

 daughters compared with 16 early and 5 late in the checks. This gives a ratio 

 of 8 early to 1 late inbred and about 3 early to 1 late check. There was, there- 

 fore, a larger proportion of late-matiu-ing birds in the check group under in- 

 breeding. 



In body weight at first egg the check pullets were superior to the inbreds. 

 This may be due in part to heavier birds used in the ancestry of the checks and 

 in part to a greater age for the checks at time of weighing. 



In percentage of puUets free from winter pause, the check group excelled. 

 There were 12 non-pause to 9 pause birds in the check group. In the three 

 inbred pens there were 17 free from pause to 46 showing pause. Thus 57 per 

 cent of the check pullets lacked pause compared with but 27 per cent free from 

 pause in the inbreds. 



From the standpoint of intensity the check pullets were superior to the inbreds. 

 In the checks there were 15 with high intensity and 6 with low intensity, com- 

 pared with 24 high and 39 low for the inbreds. Thus about three-fourths of the 

 checks exhibited high intensity, while slightly more than half of the inbreds 

 showed high intensity. Here again is further evidence that the surviving inbred 

 lines were deficient in intensity and that the check line made progress in intensity 

 even under inbreeding. 



These incomplete records offer some evidence of superiority in the check group 

 over the inbreds which may enable them to make higher annual records than the 

 inbreds. Probably this apparent superiority in characteristics affecting fecundity 

 in checks over inbreds is ascribable to greater diversity in the foundation stock of 

 the checks which would prevent inbreeding from uncovering weaknesses so readily 

 as in the narrow inbred group. There is no evidence of reduced variability in 

 age, body weight, pause, or intensity in either the check or the inbred groups 

 in Table 21. 



Graphic Presentation of Results 



A graphic presentation of the results of this inbreeding experiment is given 

 in charts 1 to 10. Each chart gives the means of dams and resulting daughters 

 for each year of the experiment both in the check groups and in the inbred groups. 

 Such a series enables the reader to see at a glance just what took place in gen- 

 eral as the experiment progressed. The charts include only mothers that actually 

 bad daughters whose records were obtained. These charts are intended only 

 to present a composite picture of results. They are in no sense a duplication of 

 the data already presented and they are of no value for genetic analysis. 



