514 GENETICS IN RELATION TO AGRICULTURE 



part in determining this position, but it must be admitted that it has 

 some other, more secure basis than this, namely in the fact that such 

 grade animals, particularly when crossed together, more often throw 

 animals off-type with reference to breed standards than do pure-bred 

 animals. Such off-type animals may not be at all undesirable from a 

 utilitarian standpoint, they may simply fail to meet fancy points which 

 breed standards insist upon. It is an open question whether livestock 

 associations may not find it conducive to advancement to provide some 

 method for the infusion of new blood, particularly in breeds which are 

 giving increased attention to performance standards. 



Crossbreeding. Crossbreeding is the term applied to crossing of 

 distinct types or breeds for special purposes. For all practical purposes 

 the Blue Andalusian fowl is one of the simplest cases of crossbreeding, 

 for it represents a simple heterozygous condition, the result of crossing 

 Black and Splashed White Andalusians. 



Crossbreeding, although often severely condemned by livestock 

 breeders, is by no means a new practice; and the persistency with which it 

 has been followed is in itself some indication of merit. The avowed 

 object of crossbreeding is to combine the excellent qualities of both breeds 

 or types which are used. Whether that object may be accomplished can 

 only be determined by trial, but in general it may be stated that for 

 complex functional characters such as speed in horses, milk or beef pro- 

 duction in cattle, wool production in sheep; in short for practically all 

 utilitarian characters a blended condition is to be expected in the cross- 

 bred offspring. The degree of excellence with which crossbred stock 

 meets the purposes for which it is bred should be the justification of the 

 practice, for sentimental considerations should have little weight in 

 dictating practical methods. 



Perhaps the best known kind of crossbred stock is the blue-gray type 

 of cattle. These cattle are crosses either between Aberdeen-Angus and 

 Shorthorn cattle or more often between Galloway and Shorthorn cattle. 

 In the early part of the 19th century the production of blue-gray 

 calves by mating the black cows of Scotland with white Shorthorn bulls 

 was so common as to arouse grave concern for the future of the Aberdeen- 

 Angus breed. The crossbreds were particularly noted for vigor and 

 rapid growth, along with high quality, uniformity, and superior utiliza- 

 tion of food. The high repute in which these cattle were held was 

 apparently based upon superior market excellence, a superiority which 

 has been confirmed by more recent trials at the Iowa station. By cross- 

 ing two beef breeds, therefore, it is apparently possible to secure an 

 animal superior to either one of them from the feeder's standpoint. 

 There is here exhibited, therefore, a rather mild form of that hybrid vigor 

 which is so often exhibited in crosses between different races within a species. 



