A STUDY IN BREEDING.

New Zealand Journal of Agriculture, Volume XII, Issue 3, 20 March 1916, Page 190

A STUDY IN BREEDING.

W. M. SINGLETON,

Assistant Director, Dairy Division

Two of our most prominent certificate-of-record purebred dairy cows represent, a phase of breeding which is considered by some authorities to be so much along modern lines that it has been deemed advisable to' draw the attention of readers of the Journal to the matter. The well-known Jersey, Lady of Collingwood, which holds the highest record for the four-year-old class of that breed, and Minnie of Glenweir, the highest-producing mature Ayrshire, are the animals referred to. It will • suit the purpose best to first . set out the tabulated pedigree of Minnie of Glenweir as it appears on page 59, Volume iv, of the Ayrshire Herd-book, as follows :

, p ., [Ayrshire King • • { Bhlebtll. / Kings Pride .. | ( Sir Robert Stout. (OamaruQueen .. | Flower> /King Cole .. f Baron Oxhin (Imp)> n „ r • (hirst Choice Maid of the Glen. * ' Winnie "In IT Tahuna. ■agj .Queen II .. jQ ueen L grS , Ari + (Bobbie Burns. \ ■ /McAllum’sPride j Vlctor y-- •• j Minerva. McAllum s Pride \ Avrshire ' L iIV | ]Queen Mary ■■ ' 6 "I ' (Sir William .. [Ayrshire King. Minnie 111 .. 1 Snowdrop. . Unie.ll

Attention is directed to 'Ayrshire King, This is one of the most noted Ayrshire bulls that have been in service in New Zealand, and that concentration of his blood indicated in the pedigree was undoubtedly most successful. A number of the earlier Ayrshire breeders have expressed the opinion that Ayrshire’s King’s daughters were exceptionally good producers, and the certificates of record which Messrs. Weir Bros. have ~ received on the yields of his descendants go to substantiate these earlier experiences. LINE BREEDING. - It ‘ will be noted that on the sire’s side there are two generations between Minnie of Glenw'eir and Ayrshire King, while on the dam’s side ' there are three such generations, making, five “ free ” generations in all. In this connection a quotation is

.apropos from the Research Committee on Animal Breeding in their .review of the work as it is carried on at various agricultural experimental stations in the United States. They state, “It has been found, to carry the matter, a step further, that most winning . racehorses during the last half-century have had five ‘ free ’ generations; prior 'to that four free generations was the rule. When there are no ‘ free ’ generations, thoroughbreds are likely to be deficient in vigour; where there are more-than five ‘free’ generations they fail, because, their speed has been swamped by outcrossing or lost by reversion.” It will be seen - that Minnie of . Glenweir’s pedigree has followed winning lines. It is obvious that the excellence of the individual whose transmissible factors are being concentrated is of paramount importance. • The foregoing pedigree affords a splendid example of line breeding. The distinction between line breeding and inbreeding is one of degree, line breeding being described as the mating of two individuals whose blood lines are the same from about 25 to not more than 50 per cent. If they are common to .50 per cent, or more it is termed inbreeding rather, than line breeding. Inbreeding would be obtained by mating a sire with his daughter, a mother with her son, and a half-brother and sister. Lady of the South in Lady of Collingwood’s pedigree would also be considered inbred, since her sire and dam have each 50 per cent, in common from K.C.B. Line breeding also suggests that the various sires used have each some of the hereditary factors of a common ancestor. INBREEDING. The pedigree of Lady of Collingwood is even more striking, so far as the appearance of common ancestors is concerned. In tabulated form it appears thus :

(K.C.B. (Imp.) .. •[ /M.L.C... .. 1 ' /• /Bilberry’s I (Sunflower V x ■ js unJ1 ‘°Vill. 1 Member R , h rryIII ..f— 6 - -(vSSl 1 ' of \Bilberry 111 •• Monopoly 11. >, J \ y | Mulberry IV. 'S.S (Sunaod (K.C.B. (Imp.). J- zC ~ , T , mm b oa.. Sunflower 11. ,9 /Sungod ’ s Member i BlueblllV ? T \ ° Lady of the J (Bluebell IV .. j ßluebell n South IKo ■ f Knight Commander {wc < toiia < in P ' ) ' Roses Sweet .. 1 . \ , 1 Sweetbrier VII .. . • | Sweetbrier 11.

The outstanding feature of this pedigree is the frequent appearance of K.C.B. a Jersey bull with eleven certificate-of-record daughters. To use a breeder’s parlance, Lady ’of the : South had

50 per cent, of her blood from K.C.B. With her was mated a grandson of K.C.8., the offspring being Lady of Collingwood. Not only was there concentration of the hereditary factors from K.C.8., but were this pedigree extended three generations further it would be found that other ancestors appear more than once. Some of these are Monologue, Monopoly 11, Dry Monopole, Monopoly (Imp.), Victoria, Sunflower, Mulberry IV, &c. In the sixth generation behind Lady of Collingwood, of sixty ancestors, the writer has counted forty-two which appear twice or in the earlier generations. In the next generation 70 per cent, of the ancestors appear twice or elsewhere, making this cow at least 70 per cent, inbred. CONSTITUTIONAL EFFECTS. Neither her inbreeding nor her three consecutive years of high butter-fat, production seem .to have had any deleterious effect on Lady of Collingwood’s constitution. It is generally held ‘ that inbreeding impairs constitution. It cannot be maintained that this is invariably the case where proper judgment is exercised. Line breeding appears to be coming more into practice with the most progressive breeders, but the uninitiated must remember that such matings are likely to accentuate any unfavourable factors as well as the desirable. No important transmissible defects should form a part of the animal whose blood is being concentrated by line breeding or inbreeding.