THEORY AND PRACITCE IN STOCKBREEDING.

New Zealand Mail, Issue 1263, 14 May 1896, Page 5

THEORY AND PRACITCE IN STOCKBREEDING.

Breeding, to be carried on safely, so that approximate conformity to a desired character may bo reached by a large proportion of the animals produced, must bo worked on a theory. The principles which are found to rule —favouring or restricting—the transmission of personal properties from parent to offspring must bo recognised and a plan of practice drawn upon the lines of those principles. For example —"Like produces (or begets) like." We therefore seek animals of the sort we wish to breed ; and, lest dissimilarity of parents should _ effect either diversity among the offspring, or in all the offspring departure from the desired character, wo match the parents as nearly as may be. But perhaps we cannot obtain just such animals as we would have. Some are faulty in one part, some in another part, none are

quite up to our standard or ideal. By \ pairing animals most like one another, faulty in the same parts, we should be likely to confirm the faidts, so that the tendency to the transmission of those faults would be exceedingly strong after a few generations had been bred in that way, and the descendants, even if crossed with animals free from tho.se particular faults, would be very likely, nevertheless, to inherit them. When, by thus borrowing from one parent the excellence needed to level up and redeem the shortcomings of the other parent, the breeder has succeeded in producing animals as nearly leprescnting his ideal as he thinks they can he made by that process, ho commonly has recourse to inter breeding from his best specimens. Then, again, the practice of matching as closely as possible is followed. The breeder's hope is that many of Lis animals will prove about equal to their parents, so that no ground shall be lost, if no ficsh ground lie gained, ; and that if .some fall below the merits of tie ir immediate parents, some pa haps, quite equal in number to those which fill shoit, may be expected to be better than their parents, Thus, first by dissimilarity, and secondly by similarity of character in their parents, the end is gained. There is always, however, the danger of reversion to faulty progenitors, and this danger demands the breeder's utmost vigilance, and the unsparing sacrifice of all offspring showing unmistakably the tendency to revert to an inferior type, The offspring of superlatively good parents j may be allowed a little indulgence if born plain or meagre; but unless the decline be promptly reversed, in the next following generation, the s.'.fest system, generally, is to weed out. The fact must be borne in mind, that however good a breeder the inferior offspring of exceedingly good parents may happen to la 1 , a backward step has occurred, and such families as begin the backward movement are very likely to repeat it. A fair margin (or variation, however, must he allowed. ft is found practically impossible, in the moat highly-improved families to breed all equally good. If a sire or dam be of extreme excellence in personal character, probably few of its sons or daughters will equal the parent ; but if tiie sous or daughters prove better than, or even equal to, the sons or daughters of Other sires or dams of similar breeding and solid worth, the offspring should not be rejected because they fail to reach the extreme excellence of the parent. That extreme excellence is to their credit, although they do not individually attain to it. The chance is a considerable one that some of their progeny will revert to something like the extreme excellence of the ancestors (especially if they be moderately interbred), although none of that ancestor's immediate offspring came up to it. All through this the theory of like, breeding like holds good ; not the less so for temporary variations; and the practice based upon it is on right lines. When, in addition to great personal merit, an animal possesses an extra, ordinary degree of power to transmit that merit to its imine Hate offspring, rapid progress is often made by the inbreelingof that animal's descendants either among themselves or by returning them to the prepotent pirent. The law of like producing like here seems \ to bo acting with curious partiality or oni sidedness; for, whilst the like of I one parent is multiplied, the other j parents, possibly, make but f'-tinr, im- j press, if any, upon I leer oii*<priiig. Still it is that law which works.

Hut there arc laws limiting each others' winking. Cheat progress has been mid' 1 , as already mentioned, by

multiplying dese.-nts from an animal which had proved its of a most powciful influence for good. Tee liberty to so use, and in so using to concentrate, the uncommonly great power found in a single animal is not unlimited. The following is an illustrative example of the kind of curb put upon the breeder's will : —-A highly intelligent farmer had a herd of good useful cows of one of the leading breeds, They had been picked up anywhere, for their good properties, without much care for the strains of blood they happened to represent, but they had pedigrees, mostly short and of miscellaneous composition. The farmer purchased an untried yearling bull, exceedingly well bred, combining two or three virtually unrelated strains, yet to a certain extent wrought together by cautious in-breeding, and unrelated to his own stock. The heifers proved such a choice lot that the farmer decided to retain that bull alone. A second generation of heifers

proved better than the first. Having succeeded twice, he thought he would

try again. In the third generation he met with some disappointments. The experiment was not altogether satisfactory. Whilst the general character was maintained, there was a manifest loss of size and constitution, and some good heifers had to be fed off for the butcher. A fourth generation, so far as the experiment went (for, if memory rightly serve, only one or two calves ever appeared), tended to indicate that a natural law against such close inbreeding under domestication, at least in the breed of cattle subjected to the experiment, limited the use of the law of like begetting like, and the farmer confessed that he had "run to the end of his tether." The puny, utterly degenerate character of the offspring of the fourth cross convinced him that the attenuated power had broken down. The old sue, fir all that, was in full vigour, and his stock from unrelated ■ cows, or from cows of the first generation, were r.s good ami as strong as those of former years. Live Stock Journal.