Different authorities give different definitions of the distinctions between line-breeding and in-breeding. Personally I have always found it impossible in practice to differentiate completely between the two. Some say that in-breeding is the mating of very close relations and line-breeding the mating of more distant relations, and in a rough-and-ready way there may be wisdom in these definitions. But if we adopt this dictum the difficulty is in knowing at what point in-breeding ceases and line-breeding commences, or vice-versa. Myself, I lean to the idea that the in-breeder is one who mates relations to fix good properties possessed by the birds which he is employing in his breeding aviary, and that the line-breeder is really establishing based upon particular "foundation" sires or "foundation" dams. In other words, he is endeavouring to reproduce particular birds with any improvements he can make upon them by skilful selection as he goes along. If this is accepted as a broad principle it will be seen that breeders of horses and breeders of cattle using outstanding sires or dams and breeding back regularly to those sire or dams and their progeny without in-breeding so closely as father to daughter or mother to son, except maybe on isolated occasions, can claim to be more line-breeders than in-breeders.
But the breeder of Budgerigars who is not opposed to the mating of relations, while he too will use foundation birds as does the line-breeder in cattle and horses, will also split together specimens very closely related and which in themselves cannot be termed "foundation" birds. Consequently I, personally, am unable to say that I am definitely a line-breeder or definitely an in-breeder. My method is really a combination of the two, which I think is satisfactorily covered by the more comprehensive term "in-breeding. " Some advocates of line-breeding prepare rather elaborate charts to show how the descendants of a given pair of birds should be mated in order to produce that ideal after a number of generations which was the objective of the commencement. The birds are treated as units and selection does not play such an important part as I consider it should do. Personally I have not a lot of faith in these charts, because I do not believe that one can ever bring the breeding of winners down to a mathematical process. It it were all so simple as these charts would lead us to believe the uncertainty of breeding pedigree animals and birds, which is one of its greatest charms, would disappear and we should all produce high-class individuals with almost monotonous regularity and ease. The breeding of superior exhibition specimens cannot be accomplished by the application of anything in the nature of mathematics.
PURPOSE OF IN-BREEDING
In-breeding is the mating of relations but the in-breeding which is advocated by so many successful livestock breeders does not mean breeding from a pair of related birds merely because they are related. The in-breeding to which this text is devoted is the pairing of related birds with a specific object, that of fixing and producing in excelsis good properties of the particular Budgerigars which are being used and the good properties possessed by their ancestors, and at the same time avoiding as far as is humanly possible intensifying faults or constitutional weaknesses. Although sensible in-breeding is the near cut to success and while the capable in-breeder will beat the man who never in-breeds, in-breeding can be a short road to failure, because it is just as easy to in-breed faults as it is good points; and it is the avoidance of the in-breeding of faults and the knowledge of the right moment at which to bring in an out-cross, if one is required, where the skill of the breeder is proved.
As I have already indicated, the in-breeder's object is to fix in the members of a strain all the good properties and none of the bad ones. If reasonable and well-applied in-breeding is employed that object can almost be attained. There is no such thing as perfection, but if it is unskilfully and carelessly applied then in-breeding can fix more of the bad points in a strain than it can good ones. Correct in-breeding not only produces birds which are good exhibition specimens but it produces birds which are capable of breeding youngsters as good or better than themselves, something which the continuous mating of unrelated stock cannot be relied upon to do. The outcome of in-breeding will be satisfactory or unsatisfactory according to the quality of the birds used in the breeding aviary. In other words, the quality of the relations mated together and their suitability to each other. It is better in every way to breed from unrelated stock in preference to putting relations together without any known reason for so doing. Such reckless in-breeding as this obviously conducted by one lacking in knowledge of the principles of in-breeding can do irreparable harm.
Consistent and intensive in-breeding should only be undertaken by one who thoroughly understands what he is about. I do not advise novices owning small studs of birds of only moderate quality to in-breed extensively in their early years. It is advisable for them to rely upon birds which they have purchased and the advice as to mating which is at their disposal by the person who sells them their stock or by experienced fanciers to whose opinions they have access. No fancier should in-breed with two birds unless he is perfectly satisfied with both their appearance and their pedigrees. He must be familiar not only with the good and bad qualities of the birds themselves but also of their parents, grandparents, and even farther back still if possible. All families have their good points and their bad points. The best families have the fewer faults, the worst families the most faults. A pair of birds can, as we all know, breed a show winner and a very bad youngster in the same nest.
The show winner may be said to be representative of the best in the family, the bad youngster representative of the worst in the family. To in-breed with that very inferior specimen would obviously be the way to produce further inferior specimens. It is advised that when deciding upon a mating, the first thing to take into consideration is the appearance of the two birds which the owner proposes to put together, and that, having become satisfied that they are a good match in so far as appearances are concerned, he should proceed to consider their parentage, if knowledge of the quality of their parents is available to him. Info about antecedents is of great importance when one is in-breeding, because in-breeding is calculated to bring to the surface latent failings handed down from a previous generation.
I will take a hypothetical case: We have before us two related birds. We desire to fix, and improve upon their own good points, and for which properties their family are generally noted. Because they are related they are both more likely to possess the ability to reproduce those good properties. If they were not related one might have the factors for the good properties. If they were related one might have the factors for the good properties but not the other, which is the reason why in a case of this kind it is wiser to mate related birds than unrelated birds. Let us assume that one of the good properties concerned is the head. Both excel in skull and our knowledge of their parents and probably their grandparents is such that we are aware of the fact that good heads are a characteristic of this particular family. Obviously, then in so far as head is concerned these two birds are perfectly suitable.
Consider all Properties
But when deciding upon a mating every property has to be considered. So we now turn to spots. We know that although this family is productive of most excellent Budgerigars, it is rare for a really good spotted youngster to come from them. They are all inclined to be small in spots. That being the case we must ascertain most carefully that neither of the two birds possesses that weakness. If both are small in spots they must not go together or we shall definitely still further engender the production of small spots, in fact in such circumstances if one is reasonably good in spots and the other poor in spots it would not be wise in-breeding to produce youngsters from this pair of birds. This is a definite rule to which all in-breeders must adhere in regards to all major weaknesses and as far as is humanely possible as regards all minor faults as well. In a word, it is of vital importance that one should never inbreed with two specimens if one of them possesses a weakness which occurs with any frequency in representatives of that particular family. Do not overlook the fact that a serious failing in an ancestor may not show itself for a number of generations, hence the great desirability of keeping accurate descriptions of the properties of any birds which have been bred from and which may have died or have been sold. When an old fault recurs unexpectedly it must receive immediate attention with a view to its elimination; otherwise in-breeding will consolidate it.
What is written with regard to the possibility of propagating property faults applies with equal force to the dangers of weakening constitution in the strain if the greatest care is not always taken to avoid in-breeding from any stock which is not absolutely constitutionally sound. You must be convinced of the health of every bird which you breed from. Adopt this plan religiously and you need not fear that well-controlled in-breeding will cause weakness of constitution. In the last few paragraphs I have deliberately stressed the dangers of continuous in-breeding if proper care is not exercised by the owner. I have done this because I know that many of those who condemn in-breeding do so because of results which it is not fair to attribute to the practice of in-breeding but which should have been rightly ascribed to the improper methods of the breeders concerned. Before you proceed to study this subject you should have well fixed in your minds the idea that the natural expectation of producing a good property in a youngster is all the greater if the factors governing the production of that good property are possessed by both parents, and that obviously the probability of both parents possessing those factors is increased if the two birds are related.
That, in a few words, sums up the value of in-breeding and gives the reason why it can be the short cut to success in the production of exhibition Budgerigars of high quality, providing the greatest care is exercised in ensuring that the two birds used will not instead of propagating good properties propagate bad properties or constitutional weaknesses. These dangers can be avoided only by the continuous exercising of careful selection and ruthless elimination.
Why Results Vary
When two good, unrelated birds are mated together they often breed some attractive youngsters because it so happens that they suit each other as mates not only as regards appearances but as regards their concealed qualities. On the other hand, as often as not when two unrelated specimens are paired they breed youngsters which are not so good as themselves or which, in fact, may be really inferior specimens. This is because they do not both carry all the factors for the most desirable properties of their species, and which diversity would probably not exist if they were related. To put is simply, these parents are good in themselves but they do not blend well. In-breeding brings "the dirt to the surface" and discloses to the owner the failings he has to contend with. In other words those points which by selection and elimination he has to eradicate from his stock.
Without inbreeding those weaknesses might have remained hidden for a lengthy period only to come forth and cause trouble in later seasons. When we know how we stand as regards the good properties and the bad properties which we have available to us in our breeding team we know better how to handle the situation. Therefore, on many occasions we should not blame in-breeding for the appearance of failings but bless it for having brought the trouble to our notice. It is as well that we should know all about weaknesses in our birds, and armed with such knowledge, proceed to eliminate them, as I have already stated, our principal object to consolidate all the best qualities in the stud and dispel the worst.
Breeding Back to One Parent
In actual practice it often occurs that one in-breeds back to one parent and not to the other. Here is an example. A cock with an extraordinarily good head and with, so far as can be ascertained, ancestors and brothers and sisters also very good in head, is mated to an unrelated hen only fair in head and not coming from a particularly good headed family. Both the cock and the hen are shapely and pleasing in other points. The youngsters from this mating are satisfactory in all their qualities except head, in which they are deficient. It can be decided that they have inherited the weakness of head from the dam. Therefore, it would obviously be a mistake to mate one of the young cocks back to its mother, as we should only be fixing weakness in head. On the other hand, it would be wise to pair one of the young hens back to her sire in order to fix his good properties, plus the other good properties which we have secured from the dam (apart from head); and at the same time we should be improving head in the next generation.
However skilful the in-breeder may be, however great the care he may exercise in the avoidance of fixing in his strain any faults of structure, color or markings, any weakness in constitution, or any tendency towards sterility or other inheritable characteristic, sometimes after a number of seasons of in-breeding with a particular family, failings unexpectedly begin to appear. Suddenly, almost without warning, some of the youngsters bred may fail somewhat in a particular point. As soon as such a sign becomes apparent, the breeder must realise that the time has arrived when an out-cross has to be made. For the purpose of example let us imagine that the birds are declining somewhat in size. We must bring in at least one unrelated specimen excelling in size and not deficient in any of the points which we have already established in excelsis in out stock. If possible we must convince ourselves that the relatives of the out-cross do not fail in those properties and are also big birds.
lf the out-cross also comes from a strain in which correct in-breeding has been employed, it is all the more valuable because it is more likely to be prepotent for its own good properties. Having purchased the out-cross (which, for the sake of explanation, we will presume to be a cock), what now has to be done is to graft his good qualities into our own in-bred family. We take the best of the young hens bred from him and mate her back to her father. Thus we secure a dose of the father on both sides. Some people, having introduced an out-cross, go so far as to mate brothers and sisters from the pair of which the out-cross is one member, but I do not advise this unless both birds are of exceptionally high quality.
I have known brother X sister produce splendid youngsters, but as a method of very close in-breeding, I prefer father X daughter or son X mother. Actually when pairing brother to sister you are only re-assembling the properties of the two parents, which theoretically may not seem to be progressive, though where two birds of outstanding merit and breeding are concerned, there are occasions, as above indicated, when this pairing be made with gratifying results. It is an excellent plan to mate the out-cross to two birds in the first season in order to breed a number of half-brothers and sisters. By pairing these half-brothers and sisters you get the blood of the out-cross on both sides, which is what you aimed to do. From the progeny of the out-cross in the first generation you can by systematic in-breeding and selection impress the good qualities of the out-cross upon the family with which you have originally merged it. It must be agreed that you always stand a better chance of fixing a property if you have the factors for that property on both sides of a mating. Now if you buy a bird for the purpose of improving a particular property, how can you ever have a dose of that property on both sides of a mating if you do not mate relatives? Without blood relationship you would always have that bird's influence on one side only.
A moment's thought will prove to you that this statement is correct. I have referred to the mating of half-brothers and sisters. I consider this to be one of the best forms of in-breeding at any time. It is particularly when utilising one of those "foundation" sires or dams to which was referred previously. These "foundation" birds are usually the outcome of skilful in-breeding. They are prepotent for their properties; they are homozygous for all that is best in a good exhibition specimen. I have known such valuable breeding forces in pigeons and other livestock which would stamp their pleasing characteristics on all their progeny no matter to what they were mated, although naturally for "foundation" birds one selects high-class mates. Having proved you are the owner of a bird of this character, halfbrothers and sisters bred from it are invaluable for carrying on the line. You want to spread through your stud all those qualities in which a "foundation" bird excels. Therefore, you breed back again and again to that bird or its progeny. Call this system line-breeding or in-breeding, it is undoubtedly the method which has brought into existence some of the most successful birds and animals of all kinds that have ever been seen. It is only by in-breeding or line-breeding, whichever you term it, that you can consolidate and improve upon the properties of a "foundation" bird.
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