BREEDING SYSTEMS 251 



If the purpose is breed improvement, using as a basis family 

 lines already established, then line breeding and, to some extent, 

 inbreeding should be followed. When new types or breeds are 

 desired, two courses are open, : either to watch for and fix mutations 

 or sports as they occur, or, more often, to accelerate possible varia- 

 tions by crossing, and then from the hybrid progeny attempt to 

 develop desired characters. But Mendel has shown this to be a 

 difficult and tedious proposition at the best, and impracticable on 

 the average poultry farm. 



If the purpose is to improve common stock at small expense, 

 then grading up is the best method. In all cases the idea should 

 be to breed from the best of the fowls which have the desired trait 

 developed to the highest degree of perfection. 



Selection. Regardless of the extent or the method of breeding, 

 the poultryman has always at command the power of selection, 

 and it is the real source of improvement. It is made possible by 

 variation, and is responsible for many of the most noted develop- 

 ments in poultry breeding. 



By selection is meant the ability to choose stock for propagating 

 purposes which possess desirable qualities, and which are prepotent 

 with regard to these characteristics, so that, with proper care, 

 the resulting progeny will be of a high standard of excellence 

 which can be maintained. To select consistently and bring about 

 definite improvement, a breeder must have a clear idea of his 

 purpose, and work continuously toward it. He must know the 

 breed with which he is working as well as its ancestry, must under- 

 stand the principles underlying selection, and use judgment in 

 departing from certain well-defined lines when compelled thereto 

 for economic or commercial reasons. 



In selection there is the important fundamental advantage 

 that it results in absolute improvement of quality, and not merely 

 in the elevation of the flock to a higher standard by the elimination 

 of the lower or average members. It accomplishes two well- 

 defined results: (1) It increases the production of individuals, 

 thereby making it possible to secure increasingly higher individual 

 records; and (2) it stimulates the average production by raising 

 the average of the mass, by eliminating the poor producers, and 

 by substituting heavier layers in their place. 



Selection should be continuously practised, not only in the 

 breeding pen, but in the elimination of weak or sick birds through- 

 out the entire brooding and growing period. Fowls which show, 



