Transactions of RHASS Volume 1940 - Page 015
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| Year | 1940 |
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L 43 ‘;.l 'm an in 31 ll : (iiiiiii 1 w ‘I "ll. ) ! ‘Ia‘: ‘ 1 '1‘: will: 18 STOCK-FEEDING UNDER WAR CONDITIONS. The amounts of by-products from imported cereals (e.g., maize gluten feed, maize germ meal, and distillery grains from imported maize and barley) are of rather minor importance. On the other hand, large quantities of oil-seeds are imported primarily as sources of oil for the manufacture of soap, margarine, &c. ; the oil-cakes represent a by-product. With the increased demand for some of the oils, it may be expected that oil-seed imports will be fairly well maintained, and that cakes will continue to be available in considerable quantity. The problem of making do with smaller imports may be attacked from three directions. Firstly, we must try to make fuller use, in feeding, of the produce of our farms ; secondly, we must try to increase our acreage of the more productive crops; and thirdly, if and when we are obliged to reduce the number of mouths, we must try to do so upon some carefully thought—out plan. On all these aspects of the problem there are certain useful lessons to be learnt from Germany, where, as is well known, the most strenuous efforts have been made, over a period of several years, to reduce that country’s dependence upon imports. THE UTILISATION 0F STRAW. One of the few materials that will be available during war in largely increased quantities is straw, and it seems that many farmers will have larger quantities available than can be put to good use for ordinary purposes—116., as litter or as fodder for cattle. It has been shown, both in Germany and in this country, that the nutritive value of straw can be increased, and its possible uses multiplied, if it is put through a simple and comparatively inexpensive process. Straw consists mainly of cellulose, a substance with the same general composition as starch, and having the same gross energy value or heat-producing power. In so far as it is digested by the animal, it has about the same food value as starch, but its digestibility is very variable. On the one hand animals with simple digestive apparatus (such as pigs and poultry) pass out in their dung a large proportion of the cellulose (fibre) of their food, whereas cattle, sheep, and horses can digest certain forms of cellulose very well. A further important point in relation to its digestibility is the form in which the cellulose occurs in the plant. All plant cells are enclosed in a wall of cellulose which, at first, is thin and soft, and hence easy to break down. In parts of the plant where strengthening tissue is not required—0.9., in a turnip or a sugar-beet—-the bulk of the cells remain in this condition. In a tree, on the other hand, the cell walls quickly thicken and lignify (turn into a woody type of cellulose), and become very indigestible. The point may be illustrated STOCK-FEEDING UNDER WAR CONDITIONS. 19 by comparing beet pulp with sawdust. Both consist largely of cellulose, but whereas the one is a valuable food for cattle and sheep the other is useless, or actually worse than useless,. as a food for any animal. In ordinary cereal straw the cellulose is artl of the one kind and partly of the other, the degree of ligfiificaiion showing a good deal of variation. In wheat and rye the process 0“oes far, and the straw of these crops isof low digestibilityf In barley and especially in cats the change is less complete and the.f0od value is consequently higher. Another point is that hgnification takes place mostly in the last stages of ripening, and goes on faster under hot and dry conditions. IIence, as is well known, oat straw from the north of Scotland is better than oat straw from the south-east of England and, as is equally well known, any straw is of better feeding value the crop has been cut somewhat green rather than dead ripe. In any straw there is, in fact a lar e amount of r' or unhgnified .cellulose which, it coild be freely 22:11:13:ng to the digestive processes, would be largely digested by cattle, sheep, and horses. But the softer tissues are enclosed and protected by the woody portions and especially by the outer skin, which is not only heavily lignified but contains a good deal of silica—the mineral that makes up the bulk of ordinary sand. - Cellulose, even in the form of sawdust, can be converted into sugar, and the process, though it is costly, is apparently beingused to some small extent in Germany; at any rate experiments have been carried out in the use of wood-sugar for pig-feedmg. By much simpler means the tiSSues of the straw can be induced to soften and swell, and at the same time the Silica can be dissolved out. This has been known for many years—indeed in the last war many thousands of tons of treated straw were produced and fed in Germany. Recently a good deal of experimental work has been done on the process in this country—by Dr Godden of the Rowett Institute and, at the instigation of Dr R. E. Slade, by Dr S. J. Watson at J ealott’s Hill, the research station of Imperial Chemical Industries Ltd. The latter has explored the possi- bilities both of a small-scale plant for the farm and of factory- sc'ale plants which might be set up (possibly in conjunction With beet-sugar factories) in those parts of England where there is a surplus of straw even in ordinary times. I Among the many processes that have been tried, some mvolvmg high temperatures and pressures, it seems that the soaking of the straw in a cold solution of caustic soda is nearly as effective as any. The procedure is first to chop the straw and then to soak it for about twenty hours in a 1% per cent solution of caustic soda. At the end of this |
| Title | Transactions of RHASS Volume 1940 - Page 015 |
