LECTURE LXXXIII. 



INFLUENCE OF IN-BREEDING AND LINE BREEDING. 



Among the many interesting phases of animal breeding no 

 one is of more general interest or has given rise to more con- 

 troversy than the subject of in or in-and-in-breeding. From 

 the earliest records to those of the present day we find this 

 method has been more or less practiced. That it has been 

 beneficial cannot be questioned. That it has in many in- 

 stances been detrimental is also likewise true. 



By in-breeding or in-and-in-breeding is meant the continu- 

 ous practice of mating these animals which are closely related 

 and then in turn using the offspring in the same way for gen- 

 eration after generation. The closest case of in-breeding is 

 that of brother and sister. The breeding of mother and son 

 or father and daughter and so on are examples of close breed- 

 ing. In fact, any method which brings together animals of 

 close blood lines may be called in-breeding. Where this 

 method is pursued generation after generation it is designated 

 as in-and-in-breeding. 



In-breeding is necessary in the beginning of any new breed 

 of stock, as it is the surest and shortest method yet known of 

 intensifying desired qualities or characteristics in the off- 

 spring. 



By following this method of breeding for a few years the 

 desired characteristics become fairly well intensified, then 

 more open or wider breeding methods are resorted to. In- 

 breeding is oftentimes resorted to as a means of securing 

 some desired end in many of the oldest and best established 

 breeds and herds. For instance, some particular color, shape 

 of body, flow of milk or quality of milk may be obtained tn 

 this way. In the development of the many of the best herds 

 of Shorthorn cattle in-breeding was practiced in a large de- 

 gree. In some instances certain breeders, who for jealousy or 

 other reasons did not care to patronize other breeders for 

 sires, used animals of their own breeding, thus followed in- 

 breeding for generation after generation. There is no doubt 



