92 MANUAL OF FABM ANIMALS 



out regard for merit is likely to find his herd deteriorating in a 

 few generations, for bad characters, if they exist in the parent, 

 will be intensified by this method of breeding just as rapidly as 

 will desirable characters (p. 78). 



In-breeding consists in mating animals closely related. It is 

 line-breeding carried to its limits, and consequently it intensifies 

 all the advantages and disadvantages of that system of breeding. 

 In-breeding has been used successfully in the improvement of 

 practically all of the present breeds of farm animals. The sys- 

 tem was first put into regular practice by Robert Bakewell, 

 and since that time has been employed more or less by all 

 successful breeders. 



The objects of in-breeding are twofold : First, more quickly 

 to secure desirable characters in the offspring; and second, 

 to render these characters more stable that they may be uni- 

 formly transmitted. Thus a certain parent, for example, a sire, 

 is found to possess an unusual degree of excellence in some 

 particular which he transmits to the offspring. To retain the 

 excellency this offspring, if a female, when of the proper age is 

 mated with her own sire, and this product, if a female, is in turn 

 mated to the same male that was her sire as well as her grand- 

 sire. This method is resorted to for three and often four genera- 

 tions with the view of intensifying and perpetuating a desirable 

 character for which the sire is especially noted. 



There are three forms of in-breeding : First, mating sire with 

 daughter, giving rise to an offspring containing three-fourths of 

 the blood lines of the sire. This method, if followed up, pro- 

 duces offspring with but one line of ancestry and eliminates the 

 characters of the dam. It is practiced when it is desired to in- 

 tensify the characters possessed by the sire. Second, mating son 

 with dam, which gives rise to offspring containing three-fourths 

 of the blood lines of the dam. This method is practiced when it 

 is desired to intensify the characters of the dam. Third, mating 

 brother with sister, a method which preserves the characters of 



