6l0 Reading-Course for Farmers. 



individuals is not confined to pure breeds, but applies equally to all 

 domestic fowls that have been kept under unnatural and forced con- 

 ditions. Hence, however important it may be to secure a variety or 

 strain of poultry having certain attributes of size, high-scoring quality, 

 or productive capacity, it is vastly more important to have fowls of 

 strong constitution with appetites to consume and with the digestive 

 power to assimilate large quantities of food. The ideal condition is to 

 have pure-bred fowls with pronounced constitutional vigor. 



Contributory causes of the loss of physical vigor 

 Among the causes tending to lower the vitality of flocks, the follow- 

 ing may be mentioned: 



(i) Increased productiveness. Modern poultry husbandry makes larger 

 and larger demands on the strength of the fowl. The wild jungle fowl, 

 from which our domestic fowls have come, is reported to lay less than 

 one dozen eggs a year. The modern fowl, under good care, is expected 

 to lay 125 to 150 or more eggs per year, and at the same time to produce 

 eggs that will yield chickens having as strong vitality as the parent. 

 It must be evident that with any increase in the average production 

 of a fowl there must be a proportionate increase in the physical strength 

 of the fowl to enable her to thrive under the larger consumption of food 

 and heavier production of eggs. 



(2) In-and-in-breeding without regard to vigor. This practice is fre- 

 quently resorted to in order to emphasize and develop high production, 

 or exhibition or other qualities. Close breeding can be followed with 

 success only when the first consideration is given to mating strong 

 individuals. Too many times the breeder has not had the courage to 

 sacrifice a weak individual because of its other desirable qualities. 



(3) The use of pullets instead of hens for breeding. By breeding from 

 pullets the breeder is undertaking to reproduce from fowls that have 

 not yet reached maturity, and that, presumably because of their well- 

 known qualities of heavy fall and winter laying, may have lowered their 

 vitality before the breeding season. It appears reasonable, therefore, 

 that the continued breeding, generation after generation, from pullets 

 instead of hens, may have a tendency to shorten the normal length of 

 life of the race of fowls, and, at the same time, to lower its native vigor, 

 while the breeding from mature fowls, two or more years of age and still 

 vigorous, should tend toward longevity and a consequent increase in 

 vitality. 



(4) Heavy feeding to induce large egg yield during fall and winter, the 

 unnatural season for egg production. The trouble here arises from the 



