12 MASS. EXPERIMENT STATION BULLETIN 411 



These data for March variabilitj' in egg weight show no parallelism between 

 mothers and daughters for classes of dams below the 3.25-gram group. For the 

 three groups of dams showing the extreme variability of 3.25, 3.75, and 4.25, 

 respectively-, there is marked parallelism between mothers and daughters. These 

 three classes of dams produced 9, 4, and 3 families, respectiveh, out of the total 

 of 119 families. These limited data further substantiate the idea that most of 

 the variabilit)^ in egg weight that appeared in March is non-genetic in character. 



Table 3. — Classes of D.\ms and of Families of 



Daughters with Respect to March Standard 



Deviation in Egg Weight. 



March March 



Standard Deviation Standard Deviation 

 of Dams of Daughters 



Gram' Grams 



+ 0.75 ±3.46 



+ 1.25 +2.51 



+ 1.75 +2.97 



+ 2.25 ±2.70 



±2.75 ±2.78 



±3.25 ±2.63 



±3.75 ±3.25 



+ 4.25 ±3.91 



Correlation Between Annual Variability in Egg Weight 

 and Annual Egg Production 



Individual annual variability in egg weight was correlated with the individual 

 annual egg record to discover whether the number of eggs laid affected the 

 variability in egg weight. The following constants were calculated: 



Number of birds 393 



Mean annual variability in egg weight, grams 2,85 



Standard deviation of annual variability ±.99 



Mean annual egg production 208.07 



Standard deviation of annual egg production ±41.53 



Coefficient of correlation — .1970 ± .0327 



Regression was found to be linear, and the coefficient of correlation ( — .1920 

 ±.0327) indicates that only about 4 percent of the variation in egg weight for 

 the year was associated with \ariation in the number of eggs. 



Correlation Between Body Weight at First Egg and Annual Egg Weight 



Evidence has been presented by a number of investigators to indicate that 

 the body weight of pullets when they lay their first egg has an important relation- 

 ship to the size of eggs laid at the beginning of the laying year and to the length 

 of the period required to attain the 24-ounce level. Data have also been pre- 

 sented by many investigators to show that mean body weight of the first laying 

 year is rather intimately correlated with egg weight. The relation between weight 

 at first egg and the mean weight of all eggs laid during the year has been less 

 extensively studied. Data now available for a six-year period throw some light 

 on this problem. The following constants were calculated from these data: 



