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. 
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