Animal Breeding In-and-in Breeding.
Animal Breeding In-and-in Breeding. No feature of animal husbandry has given rise to more controversy than that of in-and-in breeding. From the days of Bakewell onward there has been a wide difference of opinion as to the place that should be assigned to it in the experience of the ordinary breeder.
Some have regarded it as altogether helpful and others as altogether harmful. Because of this extreme difference in view the question has been much discussed in the agricultural press, and frequently to but little purpose.
These differences in opinion are doubtless the outcome of shortsighted and incomplete views on this question. Many have looked only at certain phases of the subject without viewing it in its entirety, consequently they have failed to discern the place that should and should not be assigned to it by the breeder when conducting his operations. It will be the aim in this chapter to discuss the question from an unprejudiced standpoint.
Terms that Indicate Close breeding. —The terms applied to the breeding of related animals are various, and they have been used in a sense so loose that frequently using them has brought confusion rather than clearness of conception to the mind of the reader. Such terms as in-breeding, close-breeding, inter-breeding, and in-and-in breeding, have frequently been used as though they were synonymous and legitimately interchangeable. This may be said, in a loose sense only, of the first three terms, but not of the fourth, and even in the former a shade of difference in the meaning is discernible.
The terms in-breeding, close- breeding, and inter-breeding, are used to indicate the breeding together of animals closely related, in a single instance, or at intervals of a greater or less distance. These terms have been thus applied indiscriminately, and yet as stated above, a shade of differences is discernible Avhen they are critically compared.
Manifestly in-breeding denotes the breeding together of related animals in a single instance without much regard to the closeness of the relationship.
Close breeding indicates closeness of relationship in animals thus bred. And inter-breeding naturally raises in the mind the breeding together of related animals of alien blood and should be so used.
In-and-in Breeding Defined. —The term in-and-in breeding properly indicates the breeding together of animals that are closely related for a number of successive generations. It has reference to repetition and close continuity in the breeding together of the related animals, whereas in-breeding has reference to single acts of coupling relatives, even though there should be occasional repetition in these acts. Such repetition in breeding even at intervals, would seem in a sense to involve in-and-in breeding of a weak sort, but to avoid ambiguity the author prefers to include these under the head of in-breeding.
No absolute rule has been chosen to define the ex- act degree of the relationship, nor, indeed, can it be so chosen. The animals of kin may be of the closest possible relationship, as parent and progeny, sister and brother, or the relationship may be more distant.
The closer the relationship in the animals mated the more intense the in-and-in breeding is. Since the degree of the relationship in the animals mated may differ much, the results growing out of such mating will also differ much, and this throws some light on the wide difference in view as to the value of in-and in breeding.
Practiced Purposely and Inadvertently. —In- and-in breeding has been practiced purposely and in- advertently. It has been practiced purposely by the improvers of livestock and to an end, and when judiciously practiced by them has affected great good.
The precise objects sought, or at least some of them, are given below. It has also been practiced inadvertently by the careless breeder of grades who has chosen his males from within the same herd or flock from generation to generation, and very much to the injury of the same.
The injury resulting has not grown solely out of the in-and-in breeding as such, but also from the lack of intelligence shown in the selection of the males chosen. In the selection of such males, size without regard to form has usually been the determining factor. Under such a system of breeding no substantial progress can be made.
Objects of In-and-in Breeding. —The objects of in-and-in breeding are, or ought to be,
1, the more speedily it is to secure desirable characters in animals, and
2, the quicker it is to secure uniformity and permanence in the transmission of these. The first object, then, is to secure the desirable characters and to secure them quickly. Why in-and-in breeding can affect this and do it quickly may be illustrated as follows….
In one instance take animals of mixed breeding and mate them. Choose sires of the form desired if they can be obtained from outside sources and of similar breeding and mate them. Such breeding, howsoever long continued, would not result in marked fixedness of type or indeed in fixedness of type at all.
In a second instance take animals of the same breed, though differing in form, and mate them. Continue to choose sires within the breed of desirable form, but unrelated, and mate them with the progeny and ultimately but not for several, probably many generations, will fixedness of type be reached.
In a third instance, choose females of the same breed but unlike in form, select a male of desirable form within the breed to mate with these, and select males from the progeny to mate with the females of the same. In an extremely limited number of generations unification in type will have been reached.
In the first instance the alien blood in the sires of mixed breeding becomes a disturbing factor antagonistic to fixedness in type, hence it cannot be reached by such breeding.
In the second instance purity in blood gives potency in transmission favorable to unification in form providing the unrelated sires are carefully chosen with regard to such form, hence in time fixedness in type is reached.
In the third instance related blood intensifies the transmission and usually in proportion to the closeness of the relationship in the animals mated, hence the shortness of the time required to secure unification in type.
The influences that lead to unification in type also lead to uniformity and permanence in the transmission of the same, hence the great power which in-and-in breeding has to further these ends.
In-and-in Breeding a Necessity in Forming Breeds. —In the formation of breeds, in-and-in breeding has been found a necessity, as in no other way can desirable qualities be unified speedily and rendered permanent, and in no other way can undesirable variations be quickly eliminated.
The quick unification of desirable qualities and securing permanency in them has just been illustrated. To secure these quickly, let it be observed two things are necessary; first, the animals mated must have these desirable qualities, and second, breeding them in-and-in must be practiced.
Similarly, in eliminating undesirable qualities, the animals mated must be as free as possible from these and they must be bred similarly. But to secure these results to a marked degree the greatest care must be exercised in selecting animals possessed of the desirable properties and as far as possible free from the undesirable variations. That a long time would elapse before similarity of type could be reached without in-and-in breeding has also been shown above.
In-and-in Breeding Practiced in Forming new Breeds. — Since in-and-in breeding has been found a necessity in forming new breeds, it is only to be expected that it would be practiced by the framers of new breeds and by the improvers o± all or all the improved breeds that have been so improved. It was only m a few animals that the desirable variations were found which they sought to render permanent.
To some the statement just made may seem far-fetched, but it will not be challenged by anyone who has had experience in the search for animals that represent an ideal exactly. They are few, indeed, and the higher the ideal the rarer they are. And in many instances, these have been derived from a common ancestry. Especially is this true of animals chosen within a breed as the materials to be used for its improvement.
This cannot be true, however, at the first, of the materials with which new breeds are formed from others of alien blood. But in forming these it has frequently happened that crossing and inter-crossing animals of those breeds have been practiced for some time before the attempt was made to form them into new breeds.
The excellent results obtained from such inter-crossing created the idea of distinct breed formation. The materials, therefore, that were thus used, at the time when the idea crystallized to form them into a new breed, were consequently in a sense derived from a common ancestry. Thus, it was that the Hampshire Down and Oxford Down breeds of sheep Avere established.
In-and-in Breeding more Practiced to Produce Sires. —Of course, in the formation of new breeds or types, all the animals, the progeny of these first chosen as foundation materials, were inbred. But as time went on the in-breeding became less in- tense as the progeny multiplied, and as other females were added as they sometimes were from outside sources.
In other instances, outcrosses were finally introduced, so that with the herd or type it could scarcely be said that in-and-in breeding was kept up. At the same time, it was frequently practiced more or less within one or more families from which the sires were chiefly drawn, as experience proved what science had proclaimed, that such males were more prepotent than males not thus inbred.
The advantages from in-and-in breeding are thus substantially secured with less hazard than if both males and females had been thus inbred. Because of this the in-and-in bred property in the males is more valuable than in the females.
Evils Resulting from In-and-in Breeding. —In- and-in breeding, when carried too far, will produce along with other evils: loss of size, delicacy of constitution, and general deterioration.
Illustrations of such loss are given below in each of the several ways mentioned, and these evils may be hastened or retarded by the nature of the conditions to which the animals are subjected. The influence growing out of these conditions, and which lead to delicacy will be intensified in their action through in-and-in breeding. These results would seem to be a protest of nature against the too persistent use of influences that hinder variation. Too much of sameness in form would perhaps be a greater evil than too much variation.
Loss of Size front In-and-in Breeding. —That in-and-in breeding tends to loss of size is shown in the necessity for it in breeding toy pigeons and bantam fowls. With this want of size rather than size is sought, and experience has shown, other things being equal, that the more closely the fowls are inbred the smaller they are.
The same thing is also clearly brought out in the condition of the common herds and flocks where the sires are chosen as it were in an aimless way from within the limits of the same. As a rule, the size grows less and less the longer and the more rigidly the plan is adhered to.
When such animals have been taken to other surroundings, and other sires have been brought from outside sources, improvement has at once been noticeable, and this has given rise to the popular but fallacious idea that a change in pastures and surroundings will of itself tend to renovate.
Greater Delicacy from In-and-in Breeding. — That in-and-in breeding tends to greater delicacy of constitution is evidenced in the much greater frequency of tuberculosis and other diseases in the descendants of animals that have been long inbred. Among the Shorthorn types none have been more persistently inbred than the Bates families, and it would be correct to say that in no other class of Shorthorns is tuberculosis so frequently found.
In-and-in breeding has also been carried out to a great length among certain families of Jerseys, and in these the tendency to tuberculous affections has been quite pronounced. It has further been noticed in the delicacy of many of the calves of highly inbred females.
The mortality among these is much larger than among calves of cows not thus inbred. It may not be easy to substantiate these statements in the absence of figures collected from the facts, but the belief in their correct- ness among intelligent breeders is so general as to in- fluence them when purchasing animals of either of the classes named. Or is it to be understood that they apply to any but families that have been long and persistently inbred?
This increased tendency to disease may in part be accounted for by the greater certainty with which vitiated powers arising from other causes are trans- mitted. For instance, conditions unduly artificial would sap general stamina, and the loss of stamina would accentuate the tendency toward tuberculosis begotten by in-and-in breeding.
Loss of -Reproducing Power from In-and-in Breeding.—That in-and-in breeding carried beyond a certain limit eventually leads to impaired powers of reproduction cannot be questioned, it has been so long and so frequently noticed in families that have been closely bred together for a prolonged period.
Experiments in breeding swine in-and-in for several generations have shown that breeding powers became impaired in consequence, and that physical degeneracy manifested itself in other ways.
This tendency to impaired reproduction may manifest itself in various forms. It may come in the form of impotency or the inability to beget, infertility or the inability to reproduce, or in the form of impaired fecundity, which is to say, a lessened power to breed frequently and numerously. It may also be shown in the greater tendency to abortion or in some form of organic disease of the generative organs.
But the loss of reproductive power may in many instances be intensified only, rather than caused by in-and-in breeding, and in other instances the reproductive power may be said to be latent or partially so. This will be more apparent when it is remembered that in-and-in breeding is only one of the causes of a lessened power of reproduction.
It has been noticed that some females are incapable of breeding to males near of kin to them, while they will breed to males of alien blood or of the same blood though unrelated. This would point to breeding powers in a sense latent under certain conditions, but not so under others.
General Deterioration from In-and-in Breeding. —In-and-in breeding, when long continued leads to deterioration of the whole animal system, as witnessed in the degeneracy manifested in Longhorn cattle after the master builders had passed away. The most noted breeders of these contemporary with Bakewell and after his time, followed his plan of breeding them too closely.
The outcome has been that the society for promoting the interests of Longhorns in England has gone out of existence. It would not be correct to say that in-and-in breeding alone is responsible for such a result, as the Longhorns never stood so high in the public estimate as the Shorthorns, yet the fact re- mains that it was one of the potent factors which contributed to such a result.
It is further witnessed in the necessity which compels its virtual abandonment in families in which it has been long practiced. ~No instance is on record in which in-and-in breeding has been continued in- definitely. In but few instances have it been practiced with entire success during the whole of the period covered by the experience of one individual, when such experience covered many years.
It is not recorded that Robert Bakewell was forced to modify the intensity of the in-and-in breeding which he practiced, but it should be remembered that the material with which he began was vigorous.
There are no reasons for believing that it had upon it the taint of weakened stamina, the outcome of previous in-and-in breeding. It has also been noticed that disastrous results have flowed from it wherever long practiced in the human family. The proportion of deaf and dumb in such instances, of imbeciles, of idiots, and deformed, is unusually large. Evidently no mistake was made by the divine Lawgiver in the legislation which He gave to the race prohibiting incestuous marriages.
In-and-in Breeding Cannot be Carried on Indefinitely. —Although in-and-in breeding may be adopted with much advantage for a time, under proper conditions, there is a limit which it cannot safely pass. This limit line beyond which it cannot be carried without hazard cannot be fixed by rule, as so much depends on the vigor and stamina of the stock used where in-and-in breeding is practiced. A breed with powers unimpaired by artificial conditions of domestication will longer withstand the undermining tendencies of in-and-in breeding.
The more stamina and vigor possessed by the animals at the outset, the longer, of course, can the process be continued before the evils that have been named appear. The in-and-in breeding practiced in the famous Sitty- ton herd was less intense than that practiced in the herds of some of the master Shorthorn builders, created at an earlier period, hence the Sittyton “sage,” the immortal Amos Cruikshank, was able to close his useful work on the lines on which he had all along conducted it.
In the formation of breeds, the stock chosen to be inbred are the best formed and most vigorous types that are to be found. The process is safe, therefore, and helpful for a time. But suppose a new departure were made from foundation animals already so highly inbred that they showed signs of weakened vigor, it would result in the most complete failure, however skillfully conducted. Thomas Bates, one of the most skillful of the breeders which his century has produced, was compelled to introduce certain out-crosses to mate with at least some of the animals of his herd that had been highly inbred.
Since, therefore, certain evils eventually grow out of in-and-in breeding no matter how wisely con- ducted, it should be discontinued before such evils appear. It may be difficult to tell just where the danger line is before the indications manifest themselves. These indications should be taken as warning signals by the breeder, and he should govern his work accordingly.
In-and-in Breeding Conducted Understandingly. —In-and-in breeding should not be adopted by those who do not understand it, or who may practice it in a haphazard way. It is like a sword with two edges, which cuts backward and forward according as it is wielded. When the animals so in-and-in bred are wisely chosen desirable properties will be secured and so stamped upon the progeny so as to be rendered permanent. But if the materials should be unwisely chosen then undesirable properties would appear and with a persistence that would tend to discourage those engaged in the work.
The task of selecting animals to be thus inbred is not an easy one even for the skilled breeder. How much more then is it difficult for the unskilled? Defects may be present such as those, for instance, which are not apparent to the eye, and when they are they become intensified by in-and-in breeding.
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