NORTH ISLAND FAT-LAMB CROSSES

New Zealand Journal of Agriculture, Volume 79, Issue 3, 15 September 1949, Page 219

NORTH ISLAND FAT-LAMB CROSSES

By

D. E. WALKER,

Research Officer,

Department of Agriculture Animal Research Station, Ruakura.

'T’HE Southdown-Romney lamb has. been the only fat-lamb cross of any importance in the North Island during the last 20 years. The type of lamb produced by this cross has been found most suited to New Zealand’s normal export market and, although other ram breeds have been tried, and are still being used to a very limited extent, farmers in the main have been content to conform with the policy of the New Zealand Meat Producers’ Board and concentrate on the - production of lightweight Down type lambs. Nevertheless, at the Department of Agriculture’s Animal Research Station at Ruakura advice is still frequently asked for about other crosses. Because nothing better than opinions and prejudices, based on meagre observations and hearsay, could be offered by research workers or by farmers, and because it is the task of a research station to provide facts, it was decided 3 years ago to compare the various crosses under the same environmental conditions on fat-lamb country. TO this end, for comparison with the normal Southdown and Romney as sires, six other breeds which were most common, suitable, and available were selected. These were the Ryeland, Dorset Horn, Suffolk, Border Leicester, English Leicester, and Cheviot. A selection of the rams used is shown in Fig. 1. The Sire Breeds The Southdown with its small, compact, short-legged, and deeply-fleshed body is obviously the ideal quality meat animal and is generally considered to be the most highly improved mutton breed of the world. In itself the Romney has no real importance. or prospects as a fat-lamb sire of quality, but a proportion of the wether lambs off the hill country must be slaughtered each year and they contribute a substantial percentage of the total export kill. The Romney was, therefore, included in this comparison. For many years the Suffolk, which originated from a cross between the Southdown and the old Horned Norfolk breed, has been one of the most popular fat-lamb sires in England. Both straight Suffolks and Suffolk

crosses have been very successful in carcass competitions at Smithfield, and the breed is employed to produce carcasses of 50-651 b. dressed weight. Although it is a large, long-legged breed, the Suffolk is deeply fleshed and well. proportioned. > The Dorset Horn is to some extent handicapped by its horns, which are a menace to fences in New Zealand and make handling in the shed and yards .more difficult. However, it is becoming increasingly popular in Australia, partly on account of its extended breeding season, which fits it to the marked seasonal variations of that country. Australian breeders are seeking to evolve a polled type. Although a tendency toward long legs and rather ungainly bodies exists in the breed, short-legged, deeply-fleshed, compact strains are available. Border Leicesters ' were formerly used quite extensively in , the North Island, but have practically disappeared with the increasing use of the Southdown. They are a long-legged, big-framed, hardy breed, reputedly tracing their origin, through the activity of the border raiders, to the Cheviot from the north and the English Leicester from the south. The Ryeland is a Down breed still used to a certain extent in the North Island. A larger animal than the

Southdown, it still . has the thicklyfleshed characteristics typical of Down breeds. Perhaps partly for the reason that carcasses of this cross have the reputation of not grading quite as well as those of the Southdown, it has never attained the popularity of the latter. Although the English Leicester was one o f the ear ii es improved British breeds, it does not fulfil modern requirements of either the producer or consumer. The cross is considered by. many farmers to be one of the latest maturing and more useful where iambs are fattened on crops, as in the Sou th . Island T . . ■ „ ~ ■ , , . , „ ' , In _ view of the fresh interest that s .,^ ee 2,, aroused m the possibilities of the Cheviot for second-class hill country, this breed was included for th® same reason as the Romney, although it was realised that there was little prospect of its becoming of any great importance except as a byproduct of hill farms.

TABLE I. Total % Average fattened % killed Carcass Grading Percentages return Cross off mother Ist draft wt.flb.) Down Prime Second per lamb* Southdown .. 91 39 34.6 90 8 2 34/Ryeland .. .. 94 47 34.9 39 x 56 .5 34/4 Suffolk ..' ..89 , 47 39.9 13 81 6 37/4 Dorset Horn ..9! = 54 38.1 14 81 5 36/Border Leicester ..83 48 ' 38.9 9 90 1 35/11 Eng. , Leicester . .76 29 37.1 10 87 3 35/5 Cheviot .. ..80 36 35.7 6 77 17 33/11 Romney .. ..72 18 34.9 5 73 22 33/6

All these breeds have been tried out by individual farmers in the past and have been gradually abandoned over the years in favour of the Southdown, except in the case of a small minority who have always retained their partiality for one . breed or another in the face of : public opinion and trade

demands. No definite and comparative facts in terms of figures existed, however, and in any case farms, farmers, and seasons vary and for a strict comparison the influence of these factors must be commonly shared. It was therefore necessary to compare the breeds on the same basis. Procedure For the past 3 years two selected rams of each of these breeds were mated to 50 to 60 Romney mixed-age ewes each season. The ewes were run together from the end of tupping till the lambs were drafted under typical Waikato fat-lamb management conditions at 4 to 5 ewes per acre. In the first two seasons the same pairs of rams were used, but they were all replaced in the third season. ' Results Data for all three seasons have been bulked to provide an average picture and Table 1 on the previous page gives a summary of the more important results from a farming angle. A first draft was taken in midDecember and a second, varying with season, some time in January. Rate of Maturity The Southdown, Ryeland, Suffolk, and Dorset Horn crosses all fattened well, but the Romneys, English Leicesters, and Cheviots were noticeably inferior, as might be expected. Although the. total drafting percentage of the Border Leicester cross was lower, a high percentage •of the total number fattened were ready at the first draft. It therefore- offers - possibilities where lambs are weaned on to crops. The Dorset Horn cross showed up as the earliest maturing, over 50 per cent, being killed in the

first draft each season. The latermaturing qualities of the Romney and English Leicester, on the other hand, are shown up by the low percentages sent away in the early draft. On most fat-lamb country in the North Island early maturity is a decided adjutage. Though the Southdown has always received great credit as the sire of early-maturing lambs, these results suggest that other improved mutton breeds may have comparable virtues in this respect. However, under different conditions this situation may be altered. Carcass Weight As regards carcass weight the market demand has been for lightweight (32-361 b. lambs. The Southdown and Ryeland crosses fell into this category. The heavier breeds, the Suffolk, Dorset Horn, and Border Leicester, sired heavier-weight lambs, a fact to which some importance might be attached in these days of meat shortage. Grading Quality The superiority of the Southdown cross lamb from a qualitative point of view is well illustrated by the high percentage graded Down. This percentage was not approached by any other breed, the Ryeland being the next in order with less than half the percentage, while the percentages

gained by the other crosses are almost negligible. Grading, however, has less influence on monetary returns than weight, as the average returns show.

Fig. 2 shows representative lambs on the hoof of approximately equal weight at the time of first drafting. These have been scaled to the same wither height.

An average carcass of each grade for each cross is shown in Fig. 3.

The Southdown cross lambs . are noticeably the best in each grade. They are short in the legs and wide in the gigots, giving a good cut of meat in the leg joint, are well filled in the loin, and show good development in the fore end with a minimum of low-priced neck. Fat cover is well distributed over the whole body. The only other breed grading an appreciable number of Downs was the Ryeland cross, and this shows the next best type of carcass. It is slightly longer in the leg and not so well filled in the' crutch. In the loin region there is little to choose between the two types, but the Southdown has a slight advantage in the fore end. The larger breeds, the Suffolk, Dorset Horn, and Border Leicester, all yielded carcasses 10 to 15 per cent, heavier than the Southdown cross and approximately the same percentage longer in the legs, so that as they are only slightly wider in the gigots, the conformation as a whole is not as good as that of the Southdown or Ryeland. The fore ends are not so well developed and necks are longer. Fat cover is . not as even and, in the Dorset Horn in particular, the points are inclined to be bare. The English Leicester also throws a heavier lamb than the Southdown. Carcasses of this cross are longer in body and legs and therefore deeper in the crutch, without being substantially wider in the gigots than the Southdown cross. On the whole, therefore, the type of carcass is not very desirable, although the fore end is rather better developed than those of the Suffolks, Dorset Horns, and Border Leicesters. How-

ever, some of the best lambs attain heavy weights and give good carcasses over 421 b. Under fat-lamb farming conditions the Cheviot cross measures up rather better than the English Leicester or straight Romney, but the S °f fvhh aS +h^ OdU n C f ed A oeS other ?iAna°in -th £ nAmnorathzoiv adrespo weight it has over the Southdown ; the neck" itfhtlv better l forfendhat thfmore valuable better fore end, but the more valuab e hind end is of poor conforma on. ~ ... Carcass Composition During the past season five carcasses of each cross have been dissected to obtain an indication of the relative composition of each cross in terms of bone, muscle, and fat. The carcasses were selected from the first draft and approximated as closely as possible to the average of the group in weight, grade, and carcass measurements. The dissection results are shown graphically in Fig. 4. m , , ~ . , Though on the whole differences were not very great, the Southdown cross lamb carried considerably more fat than the other crosses. In view of the demand for lean meat under rationing and pre-war complaints from the trade that New Zealand lamb carried excess fat, it appears that the capacity of other crosses to produce lean meat may be important. Recent indications point to. the need for exporting lean rather than fat meat to a market suffering from rationing. The breeds producing the heaviest weight —Suffolk, Dorset Horn, and Border

Leicester— achieve this result not. merely without excessive fat, but with more lean meat than the popular Southdown. Summary Although it is recognised that the breeds concerned may vary in their nse' to different conditions, the object has been a comparative study « .. diffprpnt rroqqpq when subJ ected to the same environmental conditions. No evidence has been obtained to suggest that the Southdown cross lamb does not merit its reputation f or p ro d i n g the most desirable type of carcass from the viewpoint of established standards of quality. Both grading results and carcass measurements confirm this. Little difference was found in the fattening ability of the Southdown, Ryeland, Suffolk, and Dorset Horn crosses approximately the same percentage of each being fattened off their mothers. The larger sire breeds, the . Suffolk, Dorset Horn,, and Border Leicester, yielded lambs 4 to 51b. heavier m carcass weight than those of the Southdown, and weight exerted a greater influence on mone tary returns to the farmers than did grading, so that the returns per jj ead we re higher for the heavier crosses than for the better-grading q nil +hdnwn rrms Southdown cross. As regards the carcass composition of the various types, the. Suffolk, Dorset Horn, and Border Leicester crosses had more bone and muscle and less fat than the Southdown cross. The data provided should at least give the fat-lamb producer a sounder basis for deciding his production policy than has been available so far.

* Calculated on opening schedule based on llgd. per lb. for Down 2’s on December 9 (the ruling price for the middle season) to overcome seasonal price fluctuations.