POULTRY NOTES — 1909. II7 



high proportion of chickens from the eggs set, and whose 

 chickens Hve through to marketable age, is an extremely de- 

 sirable bird from a practical standpoint. 



The fundamental selection index which we have chosen for 

 poultry relates primarily to the breeding capacity of the female. 

 The value of this index for a particular bird can only be deter- 

 mined after her breeding capacity has been tested. This poul- 

 try selection index comes into application in deciding which of 

 the pullets that have been tested as breeders in their pullet year 

 shall be kept over to be used as breeders in their second year 

 of Hfe. 



The formula which has been provisionally adopted in our 

 v/ork as a fundamental poultry selection index is as follows : 



5(a+b) 



c + d+i 



The following scheme shows the meaning of the letters in 

 the formula : 

 I^ := general or fundamental poultry selection index for an 



individual bird, 

 a = percentage of this bird's eggs which hatched. 

 b := percentage of eggs actually laid by this bird to the total 



number it was possible for her to lay between February 



I and June i (i. e., the breeding season) of the year for 



which the index is calculated. 



c = percentage of this bird's eggs which were infertile, 

 d = percentage of chicks hatched from this bird's eggs which 

 died within three weeks from the date of hatching. 



y\ brief discussion will make clear the reasons why these par- 

 ticular variables are chosen for the index and are arranged in 

 the formula in the manner that they are. A bird's value as a 

 breeder increases as the percentage of her fertile eggs which 

 hatch increases. Therefore a should go into the numerator of 

 the index fraction. Similarly a bird's value increases as a 

 breeder in proportion to her egg production in the breeding 

 season. A bird which produces few eggs during the breeding 

 season (whatever she may have done before) ipso facto can not 

 produce many chickens. Instead of using the actual egg pro- 



