BREEDING FOR EGG PRODUCTION 25 



a measure of the rate of functioning of the egg-producing organs. Winter clutch 

 size has increased from under two to about three and one-half at present. For 

 holding high intensity no breeders showing a winter clutch size under three should 

 be used. 



Winter pause may be reduced b\' the constant use of breeders free from this 

 undesirable character. The system of management, housing, and feeding should 

 be the most favorable at all times. 



High persistenc\' has been the last character to be developed in the station 

 flock. Though the selection of female breeders that la>- late in the fall and of 

 yearling breeders that have laid for as much as thirteen or fourteen months, 

 mean flock persistency has been raised from about 250 days to about 340 days 

 at present. No breeder with a persistency record of less than 315 days from first 

 egg should be used. A recent study shows clearly that the abilit\' to lay for more 

 than 365 days is highly desirable in breeding birds. 



Persistency is linked in inheritance with early maturity. For this reason 

 it is very advantageous to select early maturing and persistent birds early in 

 the breeding program. The ultimate goal is a flock breeding true for these five 

 desirable fecundity factors as well as for desirable breed characters and free from 

 all recognized defects. 



From what has gone before it is evident that such a breeding program should 

 not be attempted on a small scale. Only breeders that handle relativeh' large 

 flocks can hope to make consistent progress from year to year. 



The ideal hen is of very complex genetic nature and the probability of obtaining 

 any significant proportion of such individuals is very remote in small flocks. As 

 far as present information is concerned, the genetic formula of an ideal breeding 

 hen is essentially as follows: EoE'ETH'I'mmaaccPPaaBBHH. In this formula 

 the known genes for early se.xual maturity, high intensity, no winter pause, non- 

 broodiness, high persistency', large egg size, and high hatchability are considered. 



The following standard has been used in selecting female breeders in the 

 Rhode Island Red flock at the Massachusetts Station: 



Age at first egg 215 days or less. 



Weight at first egg 5.5 pounds or more. 



Intensity (winter clutch size) 3 or more eggs. 



No winter pause of more than 3 days. 

 No broodiness. 



Persistency 315 days or more. 



jNot under 24J^ ounces for pullets. 



Egg size [Not under 26 ounces for hens. 



Laying-house mortalit\' Not over 15 per cent. 



The standard should be raised as the work progresses. 



