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Breeding Dairy Cattle. 



[Oct., 



increasing the tendency to and possibility of variation, cannot 

 be a successful means of improving a herd. Crossing is some- 

 times applied to the mating of animals of different types or 

 families within a breed, and the result in this case is similar; 

 the first cross often shows a combination of the qualities of the 

 parents, but in later progeny the greater tendency to variation 

 increases the uncertainty as to the inherent qualities of the 

 progeny. 



The term " grading " is in common use in America, and 

 describes the continued mating of cows of a nondescript type with 

 pure-bred bulls of some breed having the desired qualities. This 

 method has been largely used in the past in building up several 

 of the pure breeds of the present day. The scheme of the Dairy 

 Shorthorn Association for the registration of the progeny of 

 pedigree bulls out of cows of approved type embodies the 

 principle of grading. This system offers the surest means of 

 improvement where the owner of a herd of cows of mixed 

 ancestry cannot see his way to dispose of his herd and replace 

 it by cows of a pure breed. 



In-breeding is the mating of closely-related animals, e.g., 

 sire and daughter, dam and son ,and is the opposite of crossing. 

 When this system is followed, there is great probability of the 

 appearance in the progeny of the characteristics of the parents, 

 and small likelihood of variation from the desired type. It is the 

 surest and speediest of all breeding methods for fixing the 

 characteristics which are desired, and it has been a predominat- 

 ing influence in the building up of most of our present-day 

 breeds. 



In contrast to its power for good, in-breeding, carried on 

 unwisely, may cause disastrous results. Loss of size, con- 

 stitutional vigour and breeding powers have in some notable 

 cases followed from persistent in-breeding, and at the present 

 day the practice of this system is uncommon. 



Line -breeding describes the mating of animals that are more 

 or less distantly related to each other. It might be called a 

 modified form of in-breeding, because it embodies the same 

 principle — that of concentrating and fixing family type and 

 qualities. At the same time, the degree of relationship is not 

 close enough to cause any serious risk of the development of the 

 bad effects of in-breeding. This system is extensively followed 

 in most of the pure breeds, and has given most satisfactory 

 results. Close line-breeding would be exemplified by the use of 

 two sires from the same family, each being mated with the 



