THE SCIENCE OF BREEDING.

Lyttelton Times, Volume CXXIII, Issue 15901, 12 April 1912, Page 2

THE SCIENCE OF BREEDING.

(By K. J. J. MACKENZIE, Lecturer in Agriculture, Cambridge University.)

There are some hopes that methods purely scientific may be brought to bear on the problem of the improvement or British breeds of farm live stock, but if the performances of the past are to be bettered a very great deal has to be done, for since Bakewell started, Collings. Booth, Bates and a honored other great men have followed hi his footsteps, and the improvement in our pedigree stock has been phenomenal. It will, of course, be remembered that coincident with the work of the great breeders of the eighteenth century the husbandry ~cf the country changed m such a way that it is quite possible that “feed” as well as “brood” played its part in the great advance which has led to this country ..bring called tho stud-farm of the world. If thin is so. however, it only adds to the difficulties of the future work, for at this moment no such improvement in husbandry as that which was brought about by the genius of Jethro Tull and the largemindedness of “Turnip Town;end” can reasonably bo anticipated. This being the state of tho cr'sc. it seems eminently desirable 'that tho agriculturist should thoroughly investigate every dotail of tho results of past work, so that he may be in a porition to tell tho pure scientist what aro and what are not the “points” of an animal on which ho can’ profitably work. Tho object of this article is to brine: out the. necessity and to show the difficulties of such investigation even at a very early stage. In trying to secure information dealing with tha factors which gc to make tip a “point,” one very speedily realises that if the British breeder has used his knowledge to produce stock, admittedly unrivalled in the rest of the world, he has not been at much pains to systematise his. learning so that others may avail themselves of his wisdom. ...... ’ Apart from the mere surface “points,” such as colour of skin, .texture of hair, or the shape of the horn, it is difficult at first to specify accurately what are the actual requirements sought for. There are, however, some which may bo said to bo law when certain classes cf stock are being considered. For instance, in all beef breeds of cattle one is informed either that the “rib should be well sprung ” or that “ the body should be barrelshaped,” or, again, that “ the back should be wido and thick-fleshed.” Ifaiiy further information is given, one may learn that the animal is " good at the roastings.” This latter definition is, as far as our present information goes the most truthful, if somewhat crude, definition of the point aimed | at, for to get a good butcher’s beast, the breeder aims at one which carries a large proportion of prime “joints” or “cuts, ’ and the point mentioned is valued because it denotes the presence of an abundance as well as a superior class of one particular prime joint. This joint is known in the trade as tho “ fore-rib.” It is essentially a roasting cut. It consists of the dorsal half of the four posterior ribs, the dorsal half of the three first false ribs, together with the meat or flesh carried by these seven ribs. While it is' quite possible to say that a live animal having tho point under consideration will yield a carcase carrying a goad “fore-rib,” it is not so simple to determine how the desired effect is brought about. Is the rib well sprung, i.e., has it such a shape of itself that it makes the animal like a barrel: or is it a question of the framework, formed by the horizontal line of rib and the vertical spine, carrying' a thick layer of musclo or flesh; or are both shape of bone and muscledevelopment of as much importance as the factor known to tho butcher as “marbling”? It would seem quite possible that the.infiltration, of fat into the tissue of the muscle, giving what the butcher calls a marbled flesh, may bo the deciding factor. Or, again this “point” may be somewhat influenced bv the manner in which the rib is braced at its articulation to the spinal c °lumn,ave theso four possible factors influencing this point: 1. Shapo of rib bone. _ 2. Attachment of rib to spinal column. 3. Muscular development. 4. “Marbling” or infiltration or fat into the muscle tissue. j A concrete example of' a butchers point about which it is desirable to learn more may be given. Professor Wood’s work at Cambridge on the inheritance of face-colour in sheep has led to a demand from an association of sheep breeders in Australia. ' These colonial flock-masters want a sheep bred which combines the fleece of the merino (which breed i 3 a poor butcher s sheep) with the good mutton carcase of the Shropshire Down. A most important “ point ” in the butcher s slieop is the leg of mutton. In order to get exact data whereby this point may be followed from generation to generation, Dr Marshall, of the Cambridge Department of Agriculture, and the writer of this article, finds that the following questions have to be answered: Doco the leg of mutton carried by the merino carcase fail (i.) because of the position of the sacrum with regard to the haunch bones, or (ii.) because the haunch bones are too flat, or, in technical words, because the pelvic line from ilium to ischium is not sufficiently concave to allow of proper muscular development, or (iii.) is the length of haunch bone from ilium '(hip) to ischium (pin-bone) deficient, or (iv.) is the muscle, or flesh, covering tho pelvic arch and the bones of the leg deficient or (v.) is it because of the absence of fat from this particular part of the muscular system, or, in other words, want of marbling. It would seem, as judged by inspection, that fat, in the case of the leg of mutton, plays the more important part as a covering, and that the marbling ls a secondary consideration. . " 1 easily be seen how difficult it is to ascertain exact data on all these questions. The ewes and rams mated togethci had to-be measured in respect to all the above questions, and the positions of the sheep had to be exactly the same, for experience showed that a slight movement altered the alignment A scale had to be arranged as f«r as possible to determine the state of fatness of each animal; for obviously it is necessary to know if the measuring standard is covering bone and muscle onl , or bone, muscle and a quantity of fat Having got the measurements m 1909 the investigators must wait till 1911 before the first-cross offspring w.ll 1m of the same age and consequently at the same state of growth as the parents wore at the time of measurement. Not ' we measurements of sheep with s£ep to be compared, but different measurements on tho same animal must be examined to. see if there is any correlation of “points” to bo found. ~ \ belief undoubtedly exists among practical farmers that certain “ points” 1 i rioters aro correlated I* or m“n fl d nc C e har among horses, the Shire h-rtders’ belief is that abundance of a brc l.-: i n r type of hair denotes conditional vigour. Again, abundance of straight, silky hair is said to denote „o- swine the existence of a large a™Aion of loan flesh. Face and leg P r °P° r r •„ sheep aro held to be indica- ?? °* .f a special type of mutton, wnich alleged to bo of a “shortls. j ” and distinct flavour, , which is Secularly palatable to the epicure. a vellow colour of skin and horn in ftle i° bold to denote rich milk, and riltb between the eyes is very univerbelieved to denote strength of conrtution. A short, wide head, with a well sprung, clean jaw, free from, % throatiness,” is very firmly believed

by very many graziers to denote quickfeeding capacity in bullocks. Innumerable instances of belief in some particular “ point ” denoting some particular character will be known to all who have made an extended study of animal husbandry, and it would be wearisome to refer to more than tho instances already given. . Very few who have given much attention to tlie subject would bo prepared to say that there is no truth in any of these alleged correlations. On the other hand, there is little more than the personal opinion, and that by no manner of means universal, cf the intelligent breeder, studgroom, or cowman to demonstrate the truth of the existence of (to borrow a Mendelian term) such “coupling” in live stock. It seems self-evident ' that it is necessary to ascertain how much truth there is in any or all of them, for they aro facto.rs which might be of the greatest possible value to the man cf science.

One department of this subject to which the writer has given considerable attention is represented by the “points’ of a deep milking cow. It has been Held for a long time that a milch cow should be fine at the chine, well-sprung in the rib, and wide at' the hip or hook. This idea is not of recent origin, for it is referred to by many writers at the beginning and in the middle of tho last century. It will be understood that those' “ points ” may be summed up by saying that the back of a good dairy cow should be- wedgeshaped when viewed from above. An American writer on animal husbandry, Mr William Warfield, avers this to be a fact of “common observation,” so that the belief is evidently widespread. Personal observations have led to the belief that while it is on the whole true there aro very many exceptions. It would seem that while most cows which milk well are fine at tho chine (or. to be exact, are narrow where the shoulder blades lie alongside of the spine) when they are in full milk,/many will be broad there when they have done milking, and put on flesh. It would seem, however, from handling good milkers, that such cows are wedge-shaped at the chine, i.e., that all deep-milking cows are so shaped that the shoulders aro very much closer together in front than at tho back. Put in another way, it seems, judging by handling only, that in the case of cattle which milk well, bo they good or bad for the butcher., it will be found that though the shoulder blades “over the heart” are “open ” or wide apart, the lines of the scapulas, (or shoulder blades) continued towards the head of the animal come to a sharp point. It does not seem easy to form any definite opinion about the wedge-shape of the rest of the bodv. Some cows seem to milk very well, though tlie whole length of the back from tlie chine to loin looks very narrow indeed, there being no sign of a wedge-shape. This wedge-shape would be given by a well-sprung rib, and many of the. best milkers seem to be flat-sided.

By the kindness cf their owner it has been possible to measure some of the cattle belonging to Lord Rayleigh. In these famous herds are to be found a great number oi cows kept for milk production under exceptionally skilful management, and milk records have been kept for a great many years, and these conditions are essential .to, apy real test''bf tho sort. ' ' With the assistance of Mr Gerald Strutt, and the manager (Mr H. Jones), Mr R. Beverley, of the Cambridge Agricultural Department, and the writer took a number of measurements, The method of proceeding was to measure cows that were selected owing to their record of milk production. The animals were divided, into two groups according to tlieir milk records. The forty cows in Group A averaged 814 gallons per annum, the forty oows in Group B averaged 556 gallons per annum ; the yields of milk given after first and second calf being included in all cases. • •■■ ■.■• . . There are several ways in which we have sought to test the wedge-shape of the cow by measurement. 1) As regards chine only, difference of width in front and at the back of that point. . (2) The next measurement showed the difference between the. width of ribs at the narrow point. immediately behind, tho shoulder, and the:width of ribs at tho widest point, which approximately we have always found to be on the line of the third false rib, or twelfth rib counting from tlie neck. Tlie following results were obtained: — Average of forty cows in Group A., slope 1 in 2.57; average of forty cows in group 8., slope 1 in 2.55. Here again no marked distinction lias been found, though Group B shows, the greater wedge. (3) In the third case we have tried to judge tho spring of rib by measurement. We found the ratio of arc to segment to be as follows, i.e., the same to one part in 1000 Average of 46 cons in Group A, 1.075; average of 40 cows in Group B, 1.074. 5 ) We then dealt with the wedgeshape, contrasting the-width of the cow at the front of the dime and at the, widest part of the rihf- Considering the anatomical structure, these measurements must be looked upon with a critical eye, for in the case of the rib’s’ measurement v/e have only rib, flesh and skin of the animals between the points, hut at the chine we have rib skin, flesh and shoulder-blade bone. They are interesting, however, for when judvino- a cow by inspection the eye would naturally follow the lines formed by joining up such points. It has been further held that another “point” in a milch-cow is that she should be deep in the body. The following figures give the average depth and height of the cows (in inches) m Groups A and B, and tho ratios between these measurements:—Group A, average depth 28.5, average height 51.6, percentage of depth to height 55.2; Group B, average depth 28.2. average height 51.4, percentage of depth to height 54.8. Length of quarter, i.e., from hook to pin-bone, is also claimed as a good .“point,” and the following measurements (in inches) illustrate how much truth we found in this claim when the cows were measured:—Average of 4<> cows in Group A, total length of body 59.2, length of quarter 19.3, percentage of length of quarter to total length 32.6; average of 40 cows in Group B, total length of body 58.4, length of quarter 19.2, percentage of length of quarter to total length 32.9. The quarter measurement is ono of three taken on the pelvis, all of which are held to be good “points,’ namely: —(1) Length of quarter, i.e., from hock (tho ilium) to pin-bone (the ischium); (2) width from hook, or hip (the ilium) to hook; (3) width from pin-bone (the ischium) to pin-bone. It would seem eminently reasonable to consider these j three points together, for they are measurements of tho horizontal frame on which the udder is hung. Obviously,.a largo gland will hang niore easily on a big pelvic frame than on a small one. And, all other things such as quality being equal, a largo udder will yield more milk than a small one. There is also the consideration of the large, pelvis making parturition easier. The respective sizes, and shapes of pelvic

frame found in the two groups of cattle have been compared, and it is found that the measurements come out as follows, if the size of the pelvic frame be. Compared with the size of the whole of the body Average of _ -40 cows in Group A, per cent of pelvic 1 frame to body plan, 26.4; average of 40 cows in Group B, per cent of pelvic Frame to body plan, 26.36. The figures obtained by Mr Beverley and the writer have been worked out, as shown by the above diagrams, by Professor T. B Wood, of the Cambridge School of Agriculture. Profes. sor Wood is going to subject them further to thorough tests,,ta seo if any correlation can be found in regard to any measurement and any “ point.” , ' $.

Attention may be drawn to the great difficulty found in taking the measurements, and though every care was taken, more especially in practising before beginning these actual operations among the herds in question,, wo suggest that a large amount of “ experimental error” ought to be allowod for; experience, no doubt, wiU lead to better methods and the creation of more perfect instruments. Even theiij however, it would seem difficult, without a post-mortem examination, to ascertain how- much of the difference obtained by measurement is due to the frame and how much to the condition of the animal under observation.

There aro other considerations which wo find of value when dealing with the measurements taken to enable “ the above diagrams tG be made. As has been said, all the cows measured aro in Lord Rayleigh’s herds.. They’liayo been bred, or m a few cases bought, fed, and managed, under tlie most skilful supervision, with the one idea of milk-production. It is quite possible that many of the animals which are in Class B are there from accidental cause, and that such cows, had circumstances been different, might have been promoted into Class A. We must also emphasise the fact that the cows in Class B, though the very worst in these herds, can only bo called bad milkers when contrasted ■ with those in Class A. Were it possible to get the records of some of our beef-breeds it would probably bo found that, by comparison, the cows'in Class B would be quite,good milch cattle. There is another matter which seems Worthy of consideration, and that is, that though a cow may milk well when all or many of tho _ milk-indicating points are absent, yet it is possible that she may be a less useful animal because of their absence. This may be illustrated by only one example—for this subject opens up a very vast field for speculation—a fiat-sided cow which milks well may, owing to the restriction of space in the body cavity, be unable to carry a good calf, and consequently fail as a breeder. Jt is not in any way intended to suggest that the judge in the show ring or the buyer of pedigree stock, at tho auction sale will be benefited by ob>taining such measurements. It is rather, on tho contrary, suggested that a very thorough and complete investigation should be made of the .methods employed by judges at present, so that their practice may be more completely understood. It is. however, tho object of this article to suggest how much tho agriculturist may have to do before ho is in a position to supply the scientist with that very accurate information which is essential to systematic work. The scientist, wo know, is willing and anxious to help, and it is tob« hoped that he and the agriculturist together may in the future oven improve British pedigree stock, which to-day stands, as a class, tlie best that th< breeders of the world can produce.