IMPROVING A HERD.

Hauraki Plains Gazette, Volume XXXV, Issue 4704, 28 May 1924, Page 4

IMPROVING A HERD.

LINE-BREMNG AND IN-BBEEDING. PRINCIPLES EXPLAINED. Davenport, in his book on “Principles of Breeding,” says: "By linebreeding is meant the restriction of selection and mating to the individuals . of a single line of descent. The purpose of this system of breeding is real breed improvement. Line breeding excludes everything outside the approved and chosen line of breeding. It not only combines anima’s very similar in their characters, but it narrows the pedigicc to few and closely related lines of descent. This purifies the pedigree rapidly and ancestry the largest possfele opportunity. It rapidly reduces the variable to a minimum. The nature

of results secured by this ".ystem can <: 'almost certaiitily "bfi' and ii when they do appear and improve- | f rnent is at hand it is backed* up by ■ the most powerful hereditary influ-ij cnce obtainable, because of the sim-J; plicity and strength of the ancestry. l The chief danger in line ’reeding is. that the breeder will select by pedi-, gree, abandoning the real individual selection. A line-bred pedigree is valuable or dangerous in exact proportion as the individuals have been kept up .to grade. It will not replace selection. No other system of breeding has ever secured the results that line breeding has secured. The only requirement is not to abondon individual selection.”

In-breeding is carrying line breeding to its limits, which involves the breeding together of sire and offspring, or of dam and off-spring, or of brothet and sister. Davenport says “Nobody claims advantages in inbreeding, but it is the acme of line breeding, and when superior individuals ard at hand it is a most powerful method of making the most of their excellency. It is the method by which the highest possible percentage of the bipod of an exceptional individual, or of a particularly fortunate ‘nick,’ can be preserved, fused into, and ultimately made to characterise an entire line of despent on both sides. If persisted in, the outside blood disappears by the same law that governs grading, and the pedigree is speedily enriched to an almost unlimited extent by the blood of a single animal, in practice, generally that of the sire. An in-bred animal is enormously prepotent over anything else. It is pne of the outstanding methods of intensifying blood lines, doubling up existing combinations, and making the most of exceptional individuals, .or of unusually valuable strains.” This intensifying of character works exactly the same with one character as another—-bad as well ®s good. While there are many examples of successes, failures have been masy. It is generally conceded that if inbreeding is long continued it will end in loss pf vigour and fertility. There is always the danger, too, of soffie of the bad characters being intensified. If care were always taken to select animals of great vigour, any weakness in in-breeding would disappear. —The Dairyfarmer.