30 PRINCIPLES OF SWINE BREEDING 



Longfellows are scarce. We might think we had a second 

 Longfellow, but an attempt to concentrate his blood by in- 

 breeding might prove the utter ruin of the herd, because the 

 boar might possess weaknesses which did not become apparent 

 until his progeny were inbred. 



Cross-breeding means the mating of animals belonging to 

 different breeds, and implies that both male and female are 

 pure-bred. Though a good deal of cross-breeding is practised, 

 very little systematic work has been done in the way of 

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

 and little in the best way of crossing to obtain a given result. 



Some work in cross-breeding at the Ontario Agricultural 

 College gave indefinite results, so far as cheapness or rapidity 

 of gain was concerned. There was nothing to indicate that 

 one method of crossing necessarily gave better results than 

 another, or that cross-bred pigs were necessarily better than 

 pure-breds. 



J. H. Grisdale, Central Experimental Farm, Canada, 

 reports cheaper gains from cross-breds than from pure-breds, 

 but he failed to find that any one method of crossing was 

 superior to another, so far as his work went. 



The writer's experience leads him to believe that the progeny 

 of animals which have become too fine and lack growth and 

 thrift can be much improved as profitable feeders by the 

 introduction of the blood of a more grovpthy and heavier- 

 boned type; or that animals that are coarse-boned, or slow 

 feeders, can be improved by using the blood of a finer type. 

 Frequently, however, this result can be attained without resort- 

 ing to cross-breeding, by selecting types within the same breed. 

 In the case of thrifty, rugged pure-breds, which are of a 

 type which meets the requirements of the feeder, it is difficult 

 to see how any advantage is to be derived from cross-breeding. 



