IN-BREEDING.

Otago Daily Times, Issue 19906, 28 September 1926, Page 4

IN-BREEDING.

SHOULD IT BE ENCOURTCED? FRAUGHT WITH RISKS. A PRACTICE FOR EXPERTS. “Puzzled,” Central Otago, writes asking whether in-breeding with purebreds is to be commended under special circumstances. Ho also asks for a general definition of inbreeding. Different opinions prevail regarding the effects of in-breeding, and it will generally be found that the chief opponents of the practice are in the ranks of the breeders. The generally accepted definition of the term is “the mating of animals that are closely related.” The trouble with this definition, however, lies in the varying degrees of close relationship that may exist. There is no definite outstanding as to what close relationship is and authorities differ greatly on the question. A good one to work on is contained in tho following:—“The mating of animals of precisely tho same blood, as own brother and sister, and the pairing of relations with the degree of second cousins, twice or more in succession.” All these varying shades of meaning produce little but confusion, and after all the breeder should be quite safe in accepting the term in its widest sense as it applies to the breeding of father and daughter and mother and son. Whether or not the practice should be encouraged is a difficult question to answer. Most prominent breeders, if asked, would say that if the necessity arose they would not hesitate to breed from animals of the highest degree of consanguinity, and, moreover, that many of their best animals had been produced in that manner. But such a statement would most certainly be

qualified. While not scrupling to resort to such close parentage in an endeavour to secure a certain type of animal for the flock or herd, most breeders would admit that the practice is one that should _ be used with the greatest discrimination, and then only by those fortunates who possess the rare gift of knowing how to breed. It is often found necessary, rather than run the risk of introducing outside blood, to breed much closer than would seem safe to secure the type required. hut such a course can only be adopted by experts. The concentration of blood has played a most important part in the building-up of the Dominion’s best studs, and one of the greatest objections to in-breeding is the great difficulty that is experienced in selecting animals that are absolutely free from constitutional defects. Even though the desired type is secured from close-breeding, constitutional faults exist it is certain that such weaknesses will be greatly aggravated in the offspring, and there is always a strong probability of such defects becoming dominant later on. It is on this account mainly that breeders advise their less experienced fellows to let well alone. It might seem that such counsel is inconsistent in that a man possibly cautions another about a' plan which he sometimes adopts himself. Close breeding in itself is not objected to as- being dangerous or injurious. It is chiefly because it tends to perpetuate constitutional weaknesses when practised by inexperienced people, that in-breeding comes in for such denunciation. Among careless or inexperienced farmers the plan is to be discouraged. But in the case ; of those who know the business of breeding. it can be practised judiciously with little fear. AN EXPERT VIEW.

Professor Miles, writing in a British agricultural journal, says;—“lt must be admitted that in-breeding is an important means of improvement when judiciously done, and that it constitutes the only known method of securing an accumulation of the slight variations in a particular direction, that it may be desirable to retain and perpetuate. The greatest improvement in the form and quality of animals can only be made bv those who possess the requisite knowledge and skill to enable them to blend and perpetuate nff desirable variations, through a system of rigorous selection and close breeding with out impairing the constitution by an accumulation of undesirable As a rule in-breeding is only resorted to in the case of some animal that is superior in certain respects to others, with the object of giving permanence to it« "ood qualities. Its application depends '• ho ability and knowledge of the ind' breeder.