CHAPTER XVIII 

 GENERAL LIVE STOCK IMPROVEMENT 



Heredity and Variation. — " Like begets like." This 

 tendency is known as heredity, and upon heredity are based 

 all the possibilities of live stock improvement. Offspring 

 are the result of all their ancestors, and while they resemble 

 their parents, they are never exactly like their parents nor 

 exactly like each other. It is upon variation that animal 

 improvement depends. Offspring vary slightly from their 

 parents in certain marked characteristics. The breeder 

 selects the animals that have the quaUties he desires to 

 perpetuate, and by mating them he produces other ani- 

 mals with characteristics that conform to his ideal. 



Selection. — Selection is of two kinds : natural selec- 

 tion or nature's selection of animals best fitted t6 certain 

 natural conditions, and methodical selection, or that prac- 

 ticed by the breeder. Natural selection is sometimes 

 called the " survival of the fittest," and while the animal 

 may be the fittest animal for nature's conditions it may 

 not be the best animal under economic conditions set up 

 by man. So the breeder selects his animals methodically, 

 and establishes artificial conditions under which the ani- 

 mals may best thrive. 



Atavism. — Atavism is reversion to the original type. 

 Oftentimes animals are born resembling very remote an- 

 cestors. Red calves are frequently born to black Aber- 



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