FEEDING VALUE OF GRASS.

New Zealand Herald, Volume LXVII, Issue 20519, 21 March 1930, Page 7

FEEDING VALUE OF GRASS.

ENGLISH EXPERIENCES.

SHORT-CROPPED PASTURE.

Mr. H. G, Sanders of the School of Agriculture, Cambridge, writing on the feeding valiKi of grass says:— " The most pronounced movement in British agriculture in the last ten years has undoubtedly been that away from arable land toward pasture. Much of the land laic down has, of course, been the same that was ploughed up during the War, but it is certain that the net result will bo a considerably greater proportion of grass land than in pre-waf days. This will mean that livestock will play an even greater part in. our system of farming than hitherto, for the produce of glass land can only be cashed through an animal of some sort. Whilst the laying down of arable land to grass has always been viewed as a national disaster, in the present case it is being mitigated to a large extent by an increasing tendency to farm pasture better* and to incinase its productivity: it is pleasing to be able to notice in passing that science has played a prominent part in this matter.

Some of tho most important contributions to our knowledge of grass havi been made by Dr. Woodman and his colleagues who have been carrying out most extensive studies of the productivity of paiituro plots, and of the composition and nutritive value of grass as obtained by cutting at various intervals. It is worth nolirig*that they have carried their inquixies right though to the appeal to animal («:o sheep, in point of fact) for a final verdict. The investigations have been planned on a large scale and will take a number of year:s to complete, but many interesting and useful facts hav<» already emerged. Young grass, it appears, musi be regarded as a concentrate, its dry matter having a starch equivalent, comparable with that of such foods as linseed cake: it is very rich in protein and its fibre content is low: further, the fibre is very digestible and has a nutritive ■ value equal to that of starch.. Ail grass gets more mature its protein content falls, and the fibre gets more liguifled, which means a large falling off in digestibility and nutritive value. So far the interval between cuttings has not been longer than threa weeks (except for " control " hay plots), , and no falling off in nutritive value has been found with this interval, as compared with one of one week, though the protein cor.tent has shown signs of falling: this latter is rather in the nature > of an advantage, for, in the early stages of its growth, grass is an unbalanced food for stock in that it contains too much protein.

Value of Short Grass. Perhaps the most striking result is that there is little or no variation in the composition all through the growing season, as long as the grass is kept short—thus the nutritive value of pasture i*. subject to no appreciable seasonal variation as iiuch, but it determined solely by its condition of growth. It is tru6 that theri! is a slight depression in its value at i;imes of drought (especially on light soils), but this must be attributed to the sact that uncler those conditions it makes little vegetative and approaches, maturity more quickly. Probably the chief characteristic of a first class pasture is that it contains a good succession of grasses, so that a fair proportion of the herbage is in the early stages of growth throughout a large part of the grazing season. As regards the amount of produce per acre, close cutting undoubtedly lowers the quantity of dry matter obtained, for it means a smaller area of .leaf surface, and consequently slower growth. If, however, the comparison is made on the basis of the starch equivalent produced per acre, it is found thait plots cut at weekly intervals produce nearly as much as plots cut as hay and aftermath, whilst they produce considerably more digestible protein. Fortnightly cuttings gave 29.3 per cent., and tri-weekly cuttings 62.3 per cent, more dry matter than weekly cuttings (without lowering of the nutritive value) hence there must be a considerable gain in a system of gracing which gets tha grass bitten off at, roughly, monthly intervals. Monthly intervals are being employed in the present season's investigations, and the results "will be awaited with great interest, lor the usual practice in " rotational grazing" is to allowmonthly intervals between stockings.The question is—Will the digestibility of the herbage fall so low that it loses something of its character as a concentrated food, and will the protein content be a nearer approach to that required in a balanced ration 1

Management, of Pasture. Prior to these investigations, the management of pasture land was purely an art, for the grazier had no precise knowledge of the value of the herbags his animals were eating, nor of the factors which affected it—and it must be confessed: that scientists had not realised what a valuable food it was. With these facts before him, however, he has a chance of more efficient management. There ars many points- which the inquiries have left untouched as yet, the most important probably being the question of the effects of different manures in varying quantities (the work has been carried out on unmanured pasture): this subject, and others, will, no doubt, be dealt with in due results to date, however, mark a vefy great advance: we see the great desirability of getting pastures well grazed down at short intervals (three weeks to a month is probably _the best), and that the food it provides in this state is a protein concentrate, and should be considered in that light if any supplementary feeding stuff is given. This means that, for feeding with closely grazed pasture, th<* cheaper starchy concentrates like the cereals are more suitable than the more expensive cakes with high protein content.

One other point of some considerable importance might be mentioned, and that is that the nutritive value of young herbage is only very slightly dependent on the species of the grasses providing itall common species appear to yield valuable food rich in protein in the early stages of growth, and it is only when they, approach maturity that wide differences develop between them: this indicates that close grazing is even more important on poor pastures than on good ones.