BREEDING AND MATING 85 



Factors Which Affect all Breeding. — Two distinct groups 

 of factors affect the reproduction of all animals; these are 

 particularly applicable to domestic poultry. These may be 

 termed influence of inheritance, and influence of environ- 

 ment. By inheritance is meant the transmission of charac- 

 teristics or features from the parent to the progeny. Nearly 

 all the features which yoimg chicks display dm-ing their 

 early development are inherited from the parent through 

 the egg. Shape of body is inherited. Color of plumage and 

 color of egg are inherited. In addition to visible character- 

 istics, types of temperament are inherited. The power of 

 egg production is known definitely to be inherited. Disease 

 is in a few instances hereditary, while in others not the 

 disease itself, but a tendency or predisposition to it is 

 transmitted. This factor of heredity is the greatest power 

 for improvement which the poultry keeper can bring to 

 his aid. 



The second factor is that of enviromnent, or the influence 

 of surroimdings, upon the production, development, and 

 growth of birds. Environment is operative from the time 

 the hatching egg is laid, until the resulting chick has reached 

 maturity and is marketed. Before incubation, holding the 

 egg too long or subjecting it to an improper temperature 

 will check the growth of the embryo or destroy it. Lack 

 of moisture or imsuitable temperature in the incubator will 

 result in a poor hatch of chicks. The same is true dm-ing 

 the brooding and growing season. Lack of range, green food 

 and shade will check growth and retard maturity. Unsuitable 

 environment tends to retard the natural development of 

 inherited characteristics. It must be laid down as an ele- 

 mentary principle in breeding that the best results can be 

 obtained only by the combination of two factors. Heredity 

 demands that breeding be from good birds, and environment 

 means providing them with such surroundings as will best 

 promote growth and production. 



