PROBLEM 5. Breed hi g New Types of Animals and Plains 



Fig. 444 Wheat (right) crossed with another 

 grass (left) produced the hybrid in the center. 

 Hybrids frequently show increased vigor. 



(U. S. DEPARTMENT OF AGRICULTURE) 



Fig. 445 This purebred bull is valuable because 

 he carries ge7ies for the prodtictioji of milk rich 

 in butter fat. His daughters are always better 

 than their mothers in giving rich milk. (u. s. 



BUREAU OF animal INDUSTRY) 



Altenburg's Genetics or Snyder's Prbici- 

 ples of Heredity. 



Pedigreed animals. The animal breeder 

 or progressive farmer keeps careful rec- 



497 



ords so tliat the exact ancestry, or pedi- 

 gree, of every animal is known. He 

 makes practical use of this information. 

 For example, it was noticed that bulls can 

 transmit to their daughters the character- 

 istic of producing much or little milk; 

 when, therefore, cows prove to be good 

 milk producers, the male parent, the sire, 

 is used for further breeding. From the 

 registries of the cattle breeders' associ- 

 ations one can learn which animals have 

 desirable gene combinations for a cer- 

 tain character and which have produced 

 the best offspring. Thus, by carefully 

 choosing one or both parents, stock is 

 kept up to standard or even improved. 



The second method — gene or chromo- 

 some changes start new varieties. You 

 have read how the patient breeder, 

 through systematic selection and wise 

 crossing, establishes new and better va- 

 rieties. There is a second way in which 

 new varieties start. A short-legged lamb 

 was born on a New England farm in the 

 latter part of the eighteenth century. The 

 farmer kept this lamb for breeding in the 

 hope of establishing a new breed of sheep 

 that would be too short-legged to jump 

 fences. He was successful in starting the 

 Ancon breed shown on the next page. 

 The sheep was apparently a mutant; it 

 bred true. This proved to be a highly de- 

 sirable breed until fence building became 

 easier and other qualities were sought in 

 sheep; then the Ancon breed was per- 

 mitted to die out. 



Another desirable mutation that has 

 occurred on several occasions in different 

 parts of the world is hornlessness in 

 cattle. The polled (hornless) condition is 

 desirable because such cattle are easier 

 to handle. Several breeds of polled cattle 



