VARIABILITY IN EGG WEIGHT 5 



in a frequency table to discover the character of distribution as well as the mode 

 and the mean. 



The mean March standard deviation in egg weight for the population was 

 2.05 grams. This mean is higher than the mode, which was 1.75 grams. It is 

 evident, therefore, that the distribution is slightly skewed. The fact that essen- 

 tially all of the population falls below a standard deviation of 4.5 grams indicates 

 that variability in egg weight is at a low level during March, which is an important 

 reason \vh}- selection for egg size during March of the pullet year is to be recom- 

 mended. 



The frequency distribution of March variability in egg weight, though slightly 

 skewed, is close enough to a normal frequency distribution to be considered nor- 

 mal. This fact suggests that inherited variability in egg weight may almost 

 completely disappear at this time. 



275 

 250 

 225 

 200 



> 175 



z 



W 150 



a 



^ 125 



100 

 75 



50 



25 







.75 1.25 175 225 275 3 25 3.75 4.25 4.75 5.25 5.75 6.25 675 7.25 

 MARCH STANDARD DEVIATION 



Figure 2. Frequency Distribution of Marcti Varialnlity — 765 Birds. 



The Relation of Fecundity Characters to Variability in Egg Weight 



Inherited characters affecting egg production are widely recognized by poultry- 

 men since they have been extensively discussed in the literature. Flocks that 

 are bred for high egg production are bred for uniformity in these characters. It 

 is important to know, therefore, whether these characters are in any waj^ related 

 to the variability in egg weight. 



Correla'ion Between Annual Variability in Egg Weight and Age at First Egg 



Individual variability in egg weight was measured by the standard deviation 

 between the means of the twelve months of the first laying >ear. The age at 

 first egg was recorded in days. Data are available on 423 individuals from which 

 the fr ilowing constants were calculated: 



