CHAPTER III 

 THE BREEDING SEASON 



THE arrival of puberty or the breeding age in the 

 domestic animals does not mean that the breeding func- 

 tion is exercised continuously thereafter. In the case 

 of all animals, domestic and wild, there exists a certain 

 periodicity in the process of reproduction. The phys- 

 iological activities which result in the propagation of 

 young recur with a certain rhythm, and under normal 

 conditions, there is a definite period between the 

 birth of young and the reappearance of reproductive 

 activities. 



This rhythm may be disturbed by certain external 

 conditions, although in the higher animals it recurs with 

 considerable regularity. The reproductive functions are 

 one of the first to be affected by a marked change in the 

 environment. Breeders have long recognized this fact. 

 It has been observed that a stallion or bull imported 

 from Europe to America often fails to breed well the 

 first year. The same condition has been found to exist 

 in the case of mares and cows. 



50. Changed conditions. Darwin has described how 

 changes in the ordinary habits of animals may profoundly 

 influence their reproductive functions. Animals in cap- 

 tivity rarely breed. Elephants, tigers, lions and many 

 other species when confined fail to breed at all or breed 



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