Essentials of Animal Breeding. 21 



We have, on the other hand, the accepted fact that progress in 

 animal breeding began only when breeders began to inbreed. The 

 work of Bakewell, who experimented during the last half of the 

 eighteenth century, which made the greatest impression was the 

 methods he used, and the method that has been most far-reaching 

 in its results was that he mated his animals with first regard to their 

 individual suitability for the mating, and with secondary importance 

 placed on their relationship. Since the time of Blakewell every 

 breeder who has made an impress of permanent importance on his 

 breed has used inbreeding as his most useful working tool. 



Purebred Ayrshire Bull, Hobsland Perfect Piece 16933. (Senior Grand Champion 

 Ary shire Bull. National Dairy Show, 1914.) 



FIG. 13. A good breeding animal impresses the observer in many ways. The pose of 

 this bull, his lines, and the sweep from the head to the tip of the tail give an 

 unmistakable impression of individuality, power, and merit. 



When we mate related animals we are bringing together animals 

 with a more nearly uniform character in their hereditary material 

 than when we mate those that are not related. We are, therefore, 

 increasing the probability that the offspring will be like the parents. 

 But there may be hidden in the hereditary material the factors of 

 an undesirable character. In other words, we may not know all 

 that we should know about the ancestors. Back somewhere, per- 

 haps, was a bad one whose traits are being bred out by selection in 

 each successive generation. If we mate two related animals carry- 

 ing this defect, we greatly increase the chance of perpetuating it. 

 Instead of having an even chance or better of keeping the defect under 



