10 



SWINE GEOEGE E. DAY. 



by in-breeding than most other kinds of stock, so that, when 

 everything is considered, it is safer for the average breeder 

 to avoid the practice altogether. Some of the most experi- 

 enced breeders practice a modified form of in-breeding, mat- 

 ing animals of somewhat distant relationship and bringing 

 in the blood of certain favorite strains over and over again, 

 but through various channels, thus avoiding undue concen- 

 tration of blood. This plan is commonly called "line-breed- 

 ing," but it requires great skill on the part of the breeder to 

 make it a success, and therefore it is entirely unsuitable for 

 general use. 



CROSS-BREEDING. 



Cross-breeding means the mating of animals of different 

 breeds. It dififers from grade breeding in that both the 

 male and the female are pure bred, whereas in grade breed- 

 ing, at least one of the parents is not pure bred. Though 

 a good deal of cross-breeding is practised, very little careful, 

 systematic work has been done in the way of studying the 

 relative merits of pure-bred and cross-bred hogs, and the 

 best way of crossing in order to attain a. given result. In 

 breeding for bacon in Canada, it is a common practice to 

 cross the Yorkshire and the Tamworth with the Berkshire 

 or some other fat type of hog, it being commonly believed 

 that the progeny from such a cross matures more quickly 

 and feeds more easily than a pure-bred. Whether this is 

 true or not has never been definitely established by careful 

 and repeated experiments. It is also a question whether it is 

 better to use the Yorkshire or Tamworth Boar on the Berk- 

 shire sow, or to use the Berkshire boar on Yorkshire and 

 Tamworth sows. Since the Yorkshire and Tamworth are 

 counted more prolific than the Berkshire, it would seem a 

 logical conclusion that it would be best to use sows of the 

 more prolific breeds, though many prefer to use the Berk- 

 shire sow. Where the Yorkshire and Tamworth have been 

 bred in such a way as to maintain constitution and quality. 



