Pasture and its dangers to livestock.

The Composition of Pasture Ruskin in Modern Painters eulogizes grass in the following words: “. . . judge whether of all the gorgeous flowers that beam in the summer air, and of all strong and goodly trees pleasant to the eye or good for food-stately palm and pine, strong ash and oak, scented citron, burdened vine-there beany so deeply loved, by God so highly graced, as that narrow point of feeble green”. Many of you, perhaps, quietly contemplating your well cut lawn on a summer evening might agree with him but those of us who have done any work on those aberrations of diet which cause disease must view grass with rather suspicious eyes because repeatedly we find that the cause of many of the maladies affecting livestock lies in the grass. This being the case it is all the more surprising that our knowledge of the exact chemical composition of grass is so slight and that so little interest is taken in it by agricultural research workers. A good example is the enigma of the Romney Marsh pastures where, on some fields, cattle will not fatten, while on neighbouring fields of apparently similar texture and quality, cattle fatten in a normal fashion. Many research workers have tried to solve this problem but all have failed, although various hypotheses have been advanced. To the farmer the fattening quality of pasture is his main concern and yet, much more investigation is necessary even of those aspects pertaining to energy or nutritive value of pasture. Wood (1924), summarizing the data then available, declared the starch equivalent of grass to be 50 lb., and the digestible protein, 10 lb., per 100 lb. of dry matter. Only 2 years later Woodman, Blunt and Stewart (1926), in the first of a long series of papers on the nutritive value of pasture, showed that the starch equivalent of young grass was over 70 lb., and the digestible protein about 23 lb., per 100 lb. of dry matter; in other words, young grass was a concentrate comparable in value with linseed cake and, to a grass ration, carbohydrate and not protein should be added as supplement. This was a minor revolution in our thoughts on pasture and was, indeed, the scientific basis on which was based the suggestion of utilizing dried grass, grass cake and grass silage in winter rations. One would have thought that this would be the starting point for much intensive research into the chemical composition of grass, yet we still analyse pasture under the fractions, crude protein, ether extract, crude fibre, total ash and nitrogen free extractives. Surely such appellations must be anathema to a chemist’s ingrained exactness. The nature of the crude protein is still obscure despite attempts to determine the amino-acid composition, and still less is known of the other nitrogenous substances. Recently a t