APPLICATION OF PRINCIPLES OF BREEDING 477 



until its usefulness as a breeder is nearly over. The value of a 

 stallion or a mare, or of a bull or a cow, as a breeder may be demon- 

 strated long before the animal has reached its prime. Then many 

 years of life remain in which the breeder may use a few selected 

 individuals year after year. But except in the larger and less pro- 

 ductive kinds of poultry, the breeder must make a large proportion 

 of new matings every year. The numbers produced by even large 

 stock breeders are less than those produced by the average small 

 poultry breeder. The poultry breeder usually has an abundance of 

 material for selection, and if he attends to it year by year, may 

 make much more rapid progress in any desired direction than the 

 breeder of cattle and horses. On the other hand, inattention to 

 selection of breeders for a year is almost certain to put him back 

 two or three years, while two or three years' relaxation of vigilance 

 in efforts to maintain or develop a type will usually make it neces- 

 sary for him to begin all over again. A breeder of horses or cattle 

 might neglect special attention to breeding for several years, and 

 yet, if he retained a part of his stock, take the work up again about 

 where he left it, and with the same individuals. In a like period 

 of time a neglected stock of fowls or ducks would include a very 

 small proportion of individuals of known breeding. The breeder 

 of poultry has to give practically constant attention to the selection 

 of breeders. 



Relative value of male and female. If in polygamous crea- 

 tures the females produce normally but one or two young at a birth 

 and breed but once a year, the apparent breeding value of a male, 

 bred to any given number of females, is equal to that of all the 

 females, for he has a 'one-half influence on the progeny of all, while 

 the hereditary influence of each female is limited to her own prog- 

 eny. Then whatever of peculiar merit an individual in any gener- 

 ation may take from its dam is limited to that individual. Its sire 

 and dam may reproduce its like, one or a few each year. When 

 it arrives at maturity, it may reproduce its special merit in its off- 

 spring, if a male it may reproduce its type in a considerable 

 number ; if a female, in a very limited number each year. Under 

 such conditions a male of great individual merit or prepotency is 

 much more valuable than a female. As the number of young pro- 

 duced by the female increases, her practical value in reproduction 



