78 TF.CHNICAL BULLETIN 7 



tensitj^ for the entire pullet laying year. It should furnish a reasonably true 

 measure of the bird's ability to lay throughout the year. Since the relation 

 of broodiness to annual rate has already been considered, it seems advisable 

 to correlate annual rate witli annual yield. The calculations gave the follow- 

 ing constants: 



Number of birds .... 

 Mean annual rate .... 

 Annual rate standard deviation . 

 Mean annual egg yield . 

 Annual egg yield standard deviation 

 Coefficient of correlation 



2289 



56.38 



±9.86 



172.21 



±46.61 



+.6717 ± .0077 



A very sensible positive correlation was found between annual rate and 

 annual egg yield. Annual rate is thus a very dependable measure of a bird's 

 aliility to lay during her pullet year. 



29. Correlation Between Times Broocti/ (did Annual Production — Pullet Year. 



The records of 2215 birds liroody and non-broody are taliulated and the 

 coetKcient of correlation calculated between times broody and annual^ produc- 

 tion. Constants arrived at follow: — 



Number of l)irds .... 



Mean times liroody 



Times broody standard deviation . 



Mean annual production 



Annual production standard deviation 



Coefficient of correlation 



22-15 



1.4.4 



±1.98 



173.06 



±4.6.40 



—.2126 



.0136 



This constant is false because the table is made up of two genetically dis- 

 tinct races, namely, broody and non-broody. 



Table 2. — Relation of Broodiness to Egg Record. 

 Times Broody Number of Birds Egg Record 







1 



2 



3 



4 



.5 



6 



7 



8 



9 



10 



11 



12 



13 



1121 



312 



259 



220 



149 



72 



47 



28 



17 



9 



5 



2 



1 



1 



181.31 

 178.32 

 156.62 

 156.50 

 158.65 

 162.58 

 153.59 

 140.14 

 155..50 

 147.72 

 145.50 

 160.50 

 155.50 

 145.50 



Reference to table 2 aliove sliows that the 1121 non-broody l)irds averaged 

 181 31 eggs per year. Close to this group in production is tlie class of 312 

 birds with but one broody period, averaging 178.32 eggs. A somewhat gradu- 

 al but not reaular decline begins with the group broody twice. No further 



