STERILITY 



Standing at the threshold of success in livestock breeding, is 

 the question of the capability of the animal, set aside chiefly or 

 wholly for the purpose, to reproduce living young. Without 

 this capacity, pedigree and individual excellence count for noth- 

 ing. From a practical standpoint, it matters little to us whether 

 the failure to reproduce its kind depends upon a want of impreg- 

 nation, a failure of union between the ovum and spermatozoon 

 or if it be due to the death of the embryo or fetus while yet in 

 the uterus, or even to its premature expulsion from the uterus 

 in such a defective state of health or development that it cannot 

 continue to live ; each results in a defeat of the aim of the breeder 

 and practically constitutes sterility. 



We shall here limit our consideration to the failure of the ovum 

 to become fertilized by a spermatozoon. The question of the 

 life of the embryo and fetus and the birth of the latter in a state 

 which will favor its development into a mature animal, we shall 

 consider under the head of abortion and related subjects. 



Great variations are noted in reference to the prevalence of 

 sterility in our domestic animals, it being, apparently, more com- 

 mon in the larger species. There is a somewhat general belief 

 also that it is more common in high bred individuals but this may 

 be largely erroneous. 



It certainly increases in all animals as domestication and clo.se 

 confinement increases, so that it is most common in those animals 

 which are kept closely housed and, in this way, it becomes highly 

 important in so intensely used as dairy cows. 



With many of our domestic animals, sterility does not attract 

 much attention, especially with females, because it makes com- 

 paratively little difference to the owner whether they breed, or 

 go to the butcher. We are, therefore, most interested in steril- 

 ity when it appears among animals in which their principal or 

 sole value depends upon their reproductive powers. Among 

 these, failure to breed may prove a great financial disaster. If 

 a large harem of valuable brood mares, kept exclusively for breed- 

 ing, is mated for a year with a sterile stallion, no foals are pro- 

 duced the following season and a total loss of anticipated income 

 results. In addition to this loss, each mare has deteriorated 

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