THE GENERAL ASPECTS OF ANIMAL BREEDING 451 



guide in the acquirement of that fund of practical knowledge necessary 

 to successful breeding. By this time no doubt many of the facts of 

 heredity which the student has learned must have suggested ideas of 

 practical utility, but at the risk of stating some truths already obvious, 

 a brief consideration may be given to some cardinal features which must 

 be taken into account in considering the relation of genetics to animal 

 breeding. These things must be known in order to make proper use of 

 the principles of genetics in practical animal breeding; they are mentioned 

 here in order that it may be properly understood that this text does not 

 pretend to be a complete manual of animal breeding, but merely en- 

 deavors to point out the fundamental relations existing between genetics, 

 as a pure science, and animal breeding, the craft or art of improving 

 animals and maintaining present standards of excellence. 



Foremost among the requisites of a successful animal breeder must 

 be the intimate knowledge and experience that comes from actual personal 

 contact with livestock. The success or failure of animal breeding opera- 

 tions often depends on little things, which, if neglected, destroy eventu- 

 ally all the results of the most carefully laid plans. The Bates-Duchess 

 line of Shorthorns were at one time far famed for excellence of con- 

 formation, but a neglected tendency to barrenness along with close 

 breeding resulted eventually in the extinction of this superior line of 

 Shorthorn cattle. The method of breeding employed in perfecting this 

 famous family was by no means one which from its very nature from 

 the beginning doomed the line to extinction; on the contrary, it is one 

 which gives the greatest possible degree of success provided it is applied 

 intelligently and with a full appreciation of its consequences for evil 

 as well as for good. The intimate knowledge which a breeder has of 

 his herd should include a knowledge of every individual in it. He should 

 know not only the good and bad points of the individuals but also how 

 these points are related to those of their immediate ancestors. A breeder 

 is on the highway to success when he is so well acquainted with the 

 animals of his herd that he can tell from what immediate ancestor has 

 come for instance a tendency to weakness of pastern, to a sluggish dis- 

 position, or ugliness or unwillingness under strain, and similarly for the 

 thousand and one things which must be taken into account consciously 

 or unconsciously in all breeding operations. For minute differences as 

 well as greater ones are heritable, even though as yet they have not 

 been reduced to Mendelian formulation. It would be the height of 

 folly for an animal breeder to call in a geneticist, however well trained, 

 to map out his matings for him. The services of the geneticist can only 

 be in giving the principles involved in breeding; the application must be 

 left to the breeder himself, who must temper his theoretical knowledge 

 with an abundant fund of practical detail. 



