6 MASS. EXPERIMENT STATION BULLETIN 443 



linear and the correlation was insignificant. A study of the regression line showed 

 that the digression from linearity occurred only in daughters from dams with a 

 summer clutch size of 10 or more. In any case, there appears to be no important 

 association between the summer clutch size of mothers and their daughters. 



Since mean summer clutch size in the whole population studied was essentially 

 the same as winter clutch size, the same classification of dams into low, medium, 

 and high types was used. There were 83 dams that had a summer clutch size 

 under 3. These dams produced daughters whose mean clutch size was greater 

 than their own. This could be attributed to the males to which they were mated. 

 Regression of daughters on mothers was not linear, so that the correlation ratio 

 of .2682 expresses the association, which is probably significant. 



There were 90 dams with a mean summer clutch size ranging from 3 to 4.5. 

 These have been considered medium for intensity. No correlation was observed 

 between these mothers and their daughters, and regression was found to be non- 

 linear. 



There were 57 dams in the highly intense group, with a range in summer clutch 

 size from 4.6 to 15.5. The daughters fell far below their mothers in summer 

 clutch size. Actually, this group of daughters had a slightly lower mean clutch 

 size than the daughters of the medium group of dams. The coefficient of correla- 

 tion was so low that no association was indicated, but regression was linear. 



In general, a study of the correlation between mothers and daughters in summer 

 clutch size has indicated very little advantage in selecting for breeding purposes 

 hens that have exhibited very large summer clutch size. The data would only 

 warrant the selection of breeders with a summer clutch size ranging from 3 to 

 4.5. There is the possibility that hens exhibit a summer clutch size greater 

 than about 4.5 only under most favorable internal and external invironmental 

 conditions. 



Correlation in Fall Clutch Size between Mothers and Daughters 



Pullets completing their first lading j^ear usually have a slow rate of laying in 

 September and October, but the rate of laying at this time is extremel}' impor- 

 tant from the standpoint of annual egg production, as Knox, Jull, and Quinn 

 (1935) have pointed out. These workers reported the partial correlation between 

 August and September production and annual production as .733 for White Leg- 

 horns and .727 for Rhode Island Reds. The fact becomes very evident, therefore, 

 that criteria for selecting female breeders that will transmit high fall intensity to 

 their daughters are very important. The simple correlation between mothers 

 and daughters in fall clutch size should furnish some information. 



The variability in fall clutch size was considerably lower in mothers than in 

 their daughters, and the mean fall clutch size of the daughters was low compared 

 with clutch size earlier in the laying year. No significant correlation was ob- 

 served between mothers and daughters in the total population, although regres- 

 sion was linear. This absence of correlation seems to indicate that fall clutch size 

 is affected by many environmental factors. 



Dams with a mean clutch size in the months of September and October below 

 1.7 have been considered low in intensity. There were 36 such individuals that 

 produced 224 daughters. These low intensity dams produced daughters that 

 were far superior to themselves as far as fall intensity is concerned. As might be 

 anticipated, there was no significant correlation between mothers and daughters, 

 although regression was linear. 



The medium group of mothers ranged in clutch size from 1.7 to 3.2. There 

 were 127 mothers in this group. As a whole, the daughters were similar to the 



