3i>2 



THE AVER WAX NATURALIST [Vol. XLIII 



breeder, is reproductive or breeding capacity in the birds. 

 A "200-egg" hen is of very little value as a breeder if she 

 is not able to produce when mated with a good male bird 

 a fair precentage of chickens which will live. 



It is very generally stated by practical poultrymen 

 that the point on which it is most often decided whether 

 a given commercial venture in the poultry business shall 

 succeed or fail is the expense involved in the hatching 

 and rearing of the chickens. The female that will pro- 

 duce eggs which will yield a high proportion of chickens 

 from the eggs set, and whose chickens live through to 

 marketable age is an extremely desirable 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 determined after her breeding capacity has 

 been tested. This poultry 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 life. 



The formula which has been provisionally adopted in 

 our work as a fundamental poultry selection index is as 

 follows : 



_ 5(0 + 5) 

 l *-c + d + l 

 The following scheme shows the meaning of the letters 

 in the formula : 



h = 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 1 and June 1 (/. 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 



