INTENSITY IN RHODE ISLAND REDS 7 



The present study included 430 Rhode Island Reds upon which the correla- 

 tion was determined between annual egg production and annual egg weight. 

 The following values were obtained: 



Number of birds 430 



Mean annual production — eggs 212.59 



Production standard deviation + 42.41 



Mean annual egg weight — grams 58.51 



Egg weight standard deviation + 3.79 



Coefificient of correlation + .0686 + .0324 



Correlation ratio .2297 



A positive correlation of no significant value appeared in the above 

 population of Rhode Island Reds. A test showed that the regression of egg 

 weight on annual production was non-linear. The correlation ratio was .2297, 

 of a positive order and significant. The positive nature of the association is not 

 in agreement with Marble's observations on White Leghorns, and he found no 

 evidence of non-linear regression in the Rhode Island Reds used in his study. 



Relation of Winter Production and Intensity to Annual Production 



10. Winter afid Annual Egg Production 



Winter egg production has long been used as a criterion of annual production 

 during the first laying year. The fact is also recognized that a correlation be- 

 tween winter and annual production is spurious because the annual egg record 

 includes the winter egg record. In the population studied here mean winter 

 production was 91.10 eggs and mean annual production was 213.57 eggs, giving a 

 large overlapping of records. 



In order to avoid this error the correlation was determined between winter 

 production and production for the remainder of the year. The following are the 

 constants: 



Number of birds 1470 



Mean winter production — eggs 91.10 



Winter production standard deviation. . ± 25.04 



Mean subsequent production — eggs. . . . 122.55 



Subsequent production standard deviation +34.11 



Coefficient of correlation + .0607 + .0175 



Correlation ratio .1770 



The variability in production was essentially the same during the winter 

 period and during the period covering the remainder of the year giving a co- 

 efficient of variation of about .27. This fact shows that several factors are operat- 

 ing to cause variation in the laying records of both periods. Regression of 

 subsequent production on winter production was non-linear, so that the cor- 

 relation ratio more properly expresses the association. This constant is positive 

 and significant but as a criterion of subsequent production the winter egg record 

 is of much lower value than the mean winter clutch size, as will appear later. 



11. Winter Clutch Size and Annual Egg Production 



There is no question but that intensity or rate of laying is an important charac- 

 ter affecting annual egg production. Attention has already been called to some 



