CHAPTER VI 

 STERILITY 



IT goes without saying that the first essential quality 

 in a breeding animal is the ability to produce young. 

 The more highly developed the animal is in those special 

 characters which have been fixed by selection, the more 

 important becomes the mere ability of an individual to 

 give birth to offspring. In an animal reared primarily 

 for commercial purposes, like the hog or the beef type, 

 the barren individual is not so serious a loss, as it may 

 still have a value for meat. 



It is well known that many individuals among the 

 domestic animals are sterile. Such sterility is found 

 among animals reared under the best conditions, as well 

 as among those subjected to less skillful husbandry. 

 Barrenness occurs in individuals which are a part of 

 herds or flocks in which all animals are surrounded by 

 identically the same conditions. It must be true, there- 

 fore, that some animals possess a tendency to barrenness 

 in a more marked degree than others. This tendency 

 may possibly be inherited. Barrenness may be only 

 temporary or it may be a permanent condition. When it 

 is a temporary condition, it can often be alleviated by 

 knowing the conditions which are favorable to fertility, 

 and particularly those conditions which are known to act 

 unfavorably upon the breeding functions, 

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