IN-BREEDING.

New Zealand Times, Volume XXX, Issue 4553, 23 October 1875, Page 2 (Supplement)

IN-BREEDING.

(From the Live Stock Journal.) Li briefly considering what is really meant by the axiom that “ like begets like,” we may observe that the task of the breeder would be simple, short, and easy were his attention directed only to one single point ; but as it is not so as he must consider many points, some of which are by no means correlated —it is really beset with many difficulties. _ One of these is what we call dormant tendencies ; and perhaps the next most conspicuous one lies in the fact that some animal he would gladly select for some point he desires. We are speaking, of course, concerning the more preliminary stages ; later on, when the work is done, these marked deficiencies do not—or at least should not—appear. Now, under such circumstances as these, when any breeder, who had learnt something of the principle of his art, obtained, partly by skill and partly by good fortune, some animal which to his eyes presented perfection in nearly all points, knowing as he did the necessity for throwing the transmissive powers of generation after generation into the same direction and towards the same ends, it would naturally occur to him to cross repeatedly from say the same bull; and a very little reflection will show that the success or otherwise of this plan must mainly depend upon the answers to be given to two entirely distinct questions. The first of these of course is, to what extent has the animal whose blood it is proposed thus to “ concentrate ” by in-breeding been himself the product of distinct and systematic pedigree breeding ? For it will be readily seen by any breeder that however “ perfect ” he might be in outward features, if he had no real distinctness of type it would be utterly useless to “ concentrate ” his blood ; in point of fact, in the only sense in which the word is here understood, he has no blood to concentrate. For instance, almost every shorthorn breeder who reads these lines can readily call to mind at least one example he has met with somewhere,in which a more than usually impressive bull has so stamped his image upon the progeny of a common or crossbred cow as to present nearly all the outward point- of the shorthorn, sometimes even quite all. It is notorious that such animals have won prizes at country meetings, and, being taken into service, have done much mischief by producing, quite unfairly, a mistaken impression as to the “ uncertainty ” of breeding from “ high-class bulls the progeny, in conformity with what we saw in the second of these papers, reverting to the mongrel ancestor as much as to the pure-bred one. Now, where such an animal as this is in-bred, however outwardly perfect in type, little if any good could result, since one point would come out in the one cross, some other to which there was an. equal tendency, though in his case dormant, in the next, and so on indefinitely. And these are 'not mere theories; they are facts also. Again and again have such fine “ grade ” bulls, as the Americans call them, been employed, both by them and by English farmers; in not a few cases have the unsatisfactory first results been attempted to be remedied by in-breeding, using the same bull on two successive generations ; but the result is still disappointment, and so far affords another answer to those who contend that the value of animals should be estimated only by their outward features of form,- hair, milk, or other points. That is not, however, why we mention the fact here ; but rather to show that mere “in-breeding” by itself alone is not only not sufficient a strain, but is absolutely useless. We ought perhaps to apologise for the supposition that any think otherwise; but we have reason to believe some do, and it may not be useless to have shown why such could not be the case. If any of our readers are still sceptical, let them test the matter with some of the smaller animals we have already commended for experiments of this nature. Let them cross two varieties of say rabbits ; and selecting a male from the progeny, of well-marked type, pair him ■with successive generations of females : they will very speedily be convinced in a more practical way than by any argument of ours. But the case is very different when the animal selected has been himself bred with care, bestowed on generations of his ancestors, so that his own type is already a very fixed and impressive one. Taking Favourite as

an example of what we mean; had he been merely a “fine bull,” comparatively little would have been gained by the extraordinary concentration of his blood, which has been remarked upon by nearly every shorthorn writer. But the very stock of Durham cattle with which the first breeders began to work had attained a -co siderable fixity of type ; and by the time Favourite himself was produced these originally good materials had been moulded into a more definite form still by one who is yet regarded as a master of his art. He was no chance product; used even in the ordinary way, he would have been an impressive sire for those days ; hence his “ blood” could bo concentrated with effect; but if lie had not “ blood” it would not have been so.

Beyond this even it sometimes occurs that individuals have what may be called an extraordinary power of transmitting peculiarities. Mi - . Darwin calls this power pre-potency ; and though it has been so far found impossible to reduce it to any law, or to account for it on any general principle, its existence is undoubted. When it occurs in a fine animal of good lineage it makes him specially valuable, and examples will rea'dily occur to every breeder. Such a bull, to take a late instance, was 7th Duke of York iu the Siddington herd ; and there is reason to believe that it may have been partly the discovery of such a quality in Favourite that led Mr. Colling to use him as he did ; such animals being peculiarly adapted to show the good effects of repeated in-breeding. Other illustrations will suggest themselves to every reader. Abraham married his halfsister, and successive generations to a great extent married their cousins ; and their is ground for belief that a marked individual type thus, concentrated gave the strong characteristics which distinguish the Jewish face to the present day. The Herod family, again, carried their intermarriages to an extraordinary and even incestuous degree, and they were all celebrated for as great personal beauty as moral deformity. Similar examples might easily he multiplied were it needed. The good effects of in-breeding in fixing character, then, will depend entirely on the character of the animals which are in-bred. If these he already of fairly fixed type, any marked tendency to “ sport ” or vary having been eradicated by careful selection, and the animal or animals also show good individual character and impressive power, the effect will be to fix this type far more firmly. But if the animal, however good, have no such fixed character, nothing, or at least almost nothing, can be gained by in-breeding him, the dormant tendencies counteracting the others iu each successive cross. So much, too, is comparatively simple and easily enough understood ; but we have next to consider the far wider question of the effects of upon fertility and general constitution. This will take us longer to discuss, since upon no subject connected with breeding has there been written so much iguoraut dogmatism ; while none perhaps so much requires the widest possible knowledge of facts and the broadest philosophic spirit in collating them, if we are to arrive at any solid conclusions.