FARM AND STATION

Press, Volume XC, Issue 27404, 17 July 1954, Page 5

FARM AND STATION

(By

H.S.)

STRONGER YARN AND BETTER SPINNING Advantage Of Early-Shorn Wool Whatever its advantages or disadvantages to the grower or the wool-buyer, early shearing appears to have marked advantages for the manufacturer, according to Dr. L. F. Story, director of the New Zealand Woollen Mills Research Association. In a paper given to the wool conference in Timaru last week, Dr. Story said that in manufacturing tests at present being carried out in commercial conditions, pre-lamb shorn wool was so far as a whole noticeably better than comparable post-lamb shorn wool, though it was rather shorter and the fleeces were lighter.

When two apparently equivalent lots were taken out by classing and sorting, there was absolutely no difference during carding and combing, but the pre-lamb wool gave a better spinning performance and a stronger yarn. “It has been repeatedly stated by buyers and others that early shorn wool is not very suitable for vrorsted processing as it flies on the card, gives an increased noil on combing, and eventually produces an inferior yarn as compared with wool shorn at the customary time after lambing,” said Dr. Story. “Consequently the average price paid has tended to be lower, for the pre-lamb shorn wool. We feel that prejudice has played some part, particularly as there is little or no evidence of comparative trials in which pre-lamb shorn and post-lamb shorn wools have been tested against one another under the same conditions.” Worsted Process Dr. Story explained that for worsted processing, wool of good colour and a fibre length of a minimum of about 2-i to 3 inches was needed for the Bradford system of worsted spinning. Fibres of shorter length, or fibres which broke to shorter lengths during combing, while suitable for the woollen trade, gave too much waste for the worsted trade. Wools suitable for worsted manufacture usually brought higher prices than those suitable for the woollen trade only. Four kinds of wool could be classified as early shorn, or pre-lamb shorn, he said. If hoggets were shorn before lambing their wool would be shorter and contain a larger proportion of lamby tip, and be more open than hogget wool of normal growth. When changing to pre-lamb shearing, a farmer produced wool of about nine months’ growth which was generally too short for Bradford worsted spinning, though it would be suitable for the French and woollen trades. Farmers shearing twice a year, °. r . t . hr ? e times in two years, would similarly produce wool too short for the Bradford trade. The remaining class of pre-lamb shorn wool was wool from sheep shorn in successive seasons oefore lambing. It would be exnected to be little different from wool’shorn normally except that it should in general be more free of faults. In Bradford the term ‘early-shorn’ does not necessarily mean ‘pre-lamb’ shorn, but rather prematurely shorn; that is, shorn after less than 12 months’ growth,” said Dr. Story. “It thus does not apply to full-length pre-lamb shorn wool. While the practice of shearing before lambing was growing, a considerable amount of short wool came on e market These wools were .probably tried by some combers and found to be unsuitable on account of their shorter length, and the lambiness of the hogget wools. From this it is conjectured that all pre-lamb shorn wool, including full-length pre-lamb shorn wool, has been given a bad name, especially as full-length prelamb wool, has some of the characteristics of the other types in that it is usually more open in the greasy state.”

Higher Yield The laboratory tests had been carried out only on full-length pre-lamb wool, he said. Its characteristic difference from normally shorn wools was its tendency for the fleeces to break up. It appeared to be less greasy and higher yielding, generally more free from vegetable matter, and generally sounder than normal wool. It was also usually shorter. “On account of the difference in appearance of the pre-lamb shorn wool which causes it not to confirm to the standard types of post-lamb shorn wool, and because word has got around that the pre-lamb shorn wool is inferior in its processing qualities, there has been a tendency for buyers to pay less for pre-lamb shorn wool,” said Dr. Story. “We at the Research Association could not see why there should be any particular difference in the processing properties dependent on the shearing time. Arguments that are put forward about the ‘feeding’ of the wool and changes occurring in the fibres at lambing-time are known on scientific grounds to be invalid.” Dr. Story discussed the tenderness or break that frequently occurred in wool about lambing time, and said that the causes were uncertain, except that they must arise from a metabolic disturbance in the sheep. In wool shorn at the normal time the fault came about half an inch to an inch from the butt of the staple, but in prelamb shorn wool it came very close to the tip. Tenderness at the tip, which was in any case subjected to damage by weathering and light during the 12 months’ growth, was of little consequence if the rest of the staple was sound right down to the butt and therefore superior for worsted processing. “It has been stated that as the greasy pre-lamb shorn wool is more open it will subsequently produce fly and waste, while the top will be loose, and the yarn loose and slippery.,” said Dr. Story. “It is granted this wool often looks different in the fleece, but it must be remembered that in processing the fleece is scoured to remove the large amount of impurities present in the raw wool and the fibres are then completely separated from one another by carding, so that the characteristics of the fleece are completely lost. It is the property of the fibres themselves that matter in processing. As the greater part of the fibres would be expected to be the same whether the fibres were shorn before or after lambing, little difference in processing behaviour would be expected.” In the first trials made by the association to compare the performance of the two types of wool, Corriedale and medium crossbred pre-lamb and postlamb wools of typical good grade were bought at auction. Little, was known of the history of the crossbreds, but it was known that the post-lamb Corriedale lot was of 13 months’ growth. This, as well as other possible factors, could have accounted for the considerably greater yield of combing length fibres found during sorting in the cost-lamb Corriedale. The prelamb’ lot took longer to sort because of the tendency of the fleeces to break up. After sorting, the two lots of Corriedale were scoured, carded, and combed. Pre-lamb wool yielded about 3 per cent, more scoured wool than the post-lamb shorn, and gave rather less noil or combing. No differences were noted in the yarns, which were identical in strength and evenness. The crossbred lots were less carefully sorted and ony a proportion of finer wools was removed. This time the yield of the pre-lamb shorn wool was the lower. There was a negligible difference in the amount of noil on combing. The pre-lamb wool gave a better spin with fewer breakages of the thread on the machine. The yarn was slightly less strong, but not enough to matter. The trials showed that the only real difference between the lots was the time taken in sorting, which was expected. Invermay Flock

The next trial was conducted with sheep at the Invermay research station, where last season a study was made of a Romney cross flock, run in identical conditions, part' of which was shorn regularly before lambing, and part after lambing. This enabled any differences other than time of shearing to be eliminated as far as possible. The early shorn flock, numbering 153, was shorn at the end of August, and the rest, numbering 134, were shorn at the

end of November. Each fleece was weighed and staple lengths measured as it was classed and examined. the pre-lamb fleeces, 0.9 per cent, were found to be dingy, wasty, or poor colour, or cotted. Of the post-lamb fleeces, 3.5 per cent, were found to be tender, badly x coloured, or cotted. Among the pre-lamb fleeces, 72.5 percent. were classed at AA and 27.5 per cent at A, but among the post-lamb fleeces, 57.5 per cent, were classed as AA and 42.5 per cent, as A. The prelamb fleeces were therefore more free from fault. Differences in length of staple and in fleece weight favoured the postlamb wool, which had a fleece weight of 9.41 b against 8.71 b, and a staple length of 7.4 in against 6.95 in for prelamb shorn. The difference in length and the associated difference in fleece weight might have been due to seasonal differences, said Dr. Story, and in case the difference was real, as it was stated to be by the trade, experiments had been started to find where it arose. The main line of wool from each lot was exhibited at one of the Dunedin wool stores,. and buyers’ comments invited. Most of them gave an assessment of yield, and the average of these assessments was in favour of the post-lamb shorn wool. As the pre-lamb shorn wool had been baled for over three months as against three weeks for the other, it looked rather dull and dusty by comparison. Tests for yield were made by the Department of Agriculture, and the actual mill yield was ascertained, and the three sets of figures were as follows:

Waste in scouring and carding was at 4.1 per cent., exactly the same for each lot. The two lots were subsequently combed in succession on the same machine, and each yielded 95 per cent, of top. Noil from the pre-lamb lot was 4.3 per cent, against 4.2 per cent, for the other, and waste was 0.7 per cent, from the pre-lamb lot, and 0.8 per cent, from the other. The difference between the two lots was thus negligible. Fibre fineness and length in the top were then measured, and it was found that now there was a slightly greater fibre length in the pre-lamb lot, which was also rather more even in length. This could only be due to more fibrebreakage in the post-lamb lot during carding and combing, and indicated that it jvas slightly tender. Eveness of Fibre There was no difference in waste during spinning, but the pre-lamb lot gave a better spin as shown by the lower number of breakages of the threads on the spinning frame. This superiority was probably due to the greater evenness of fibre length. The strengths of the various yarns were tested and the pre-lamb lot was found to be superior. For three months of the year, prelamb shorn wool is in the bale while post-lamb wool is still growing on the sheep, and Dr. Story said that observations were being continued to try to determine whether seasonal differences might account for the difference in fibre length and fleece weight. Measurements of rate of growth were also being made to find whether time of shearing had any effect. “It is too early to have any results from this work, but one interesting preliminary observation was made lasi year,’’ said Dr. Story. “This was that the length of wool grown in the period August-November was usually greater if wool had been shorn in August. In some of the few cases where it was less there was cotting and break in the November shorn wool.

“It is also hoped to find why there is a difference in the openness of the fleeces when shorn before or after lambing. It is thought this may be due

to a slight shedding of fibres at lambing time, insufficient to cause noticeable cotting, but enough to bind the staples together. This theory is supported by the observation that the top from the pre-lamb shorn wool was the more even in length.” CROPS AND PASTURES The Department of Agriculture report on crops and pasture in the northern half of the South Island for July says:— North Canterbury wheat crops have been sown under ideal conditions. Strikes have been good and initial progress very satisfactory. Unfavourable weather has delayed Marlborough sowings and flood waters destroyed several recent sowings.

Green feed barley crops are making good progress. Ground preparation for spring sowings is under way, and the possibility of only small contract area requirements is causing some concern amongst farmers and merchants.

- Potato digging has been almost completed in most areas. Digger damage is prevalent in early harvested crops in the Waimate area and difficulty is being experienced in grading these lines to F.A.Q. standard. Timaru and mid-Canterbury crops have been lifted in good condition. All districts report good yields but slow demand. Young stands of ryegrass have continued to make good progress an.d are looking extremely well. Areas intended for white clover seed are also reported to be making very satisfactory progress.

Feeding out has commenced in all districts, and owing to the comparatively mild weather and continued growth of pastures, winter forage crops are proving more than adequate and it is practically impossible to dispose of surplus reserves. Pasture growth continued on most pastures up till the occurrence of severe frosts over the latter half of June. Autumn sown areas are looking particularly well and have made exceptionally good growth. Porina infestations are reported to be severe in established pastures in parts of Waimate district and in Mid-Canterbury, and appear widespread throughout Canterbury where many areas are showing signs of damage.

Prelamb Postlamb Buyers’ assessment .. 74.5 76.5 Dept, of Agriculture 77.45 77.85 Mill yield .. 77.9 78.5