NUTRITION IN FODDER.

New Zealand Herald, Volume LXIII, Issue 19509, 13 December 1926, Page 16

NUTRITION IN FODDER.

CAMBRIDGE EXPERIMENTS. i INFLUENCE OF SUNLIGHT. .HOW TO USE KNOWLEDGE. No. IT. BY SUNDOWNER. The experimenters at Cambridge state that "It was also shown that the aftermath samples from the hay plots resembled closely in chemical composition the pasture samples ait during the same period." This clearly proves that at one stage of its growth the grass ceased to extract nourishment from whatever source "it drew it, as, when both were the same '.'length, the nourishment in both was equal. Let us assume, for a moment, that the sroofs have nothing, or practically noth- ; ing, to do with the production of nourish'jnent as we assess it when considering ; the value of grass for grazing animals. "The roots extract from the soil moisture and a .very minute quantity of mineral substances necessary for tho frame of the • plant, besides a very small quantity of ' nitrogen. All these can be accurately estimated by analysis, but nutritive value has neither weight nor*bulk.

In my first article I emphasised the fact that animals neglected grass- grown in the shade, or away from tho sunlight; they also neglect long grass where short is available. Is it not possible then that

'the whole of this nutritive yalue is deprived directly from tho sun's rays? a field of long grass. The tops '.: may be waving, dark green, but a few -inches down, where the sunlight is unable fio penetrate, the colour shades from pale green to whits. With short grass, where the sun's rays . are able to penetrate throughout the whole length of tho grass, '{tho leaves and stems are deep green to the ground surface. Put stock into the long grass pasture and what happens ? The stock do not eat the grass right down to the ground, but 'first of all nibble off the top growth only, the blades which are stored with food extracted from the sun's rays. With this nourishing "top" removed tho sunlight is then able to penetrate deeper into the long grass, and this in turn becomes charged with "nutritive value" and is greedily eaten. That nutritive value and flavour are one is evident from the fact that all animals which subsist on grass will not, unless insufficient grows to keep them alive, leave short grass to eat long grass, which is thus allowed to become longer and longer, and that this nutriment is derived solely from the sunlight is evidenced by the fact that, however short it may be, animals will leave pasture which "lies away from the sun" for that which is exposed to its rays. Power o! Sunlight. I have put forward the theory that a f large proportion of the plant's nutritive value, or in other words the energy which makes it nourishing and therefore palatable to the animal, is drawn by the plant from the sunlight. The reason that short grass contains double the nourishment of long • grass is that the whole plant is exposed to the sun's rays and is busily employed absorbing and storing this energy, Vhile in the longer grass only one-third or at most one-half of the plant comesi in contact with the sun. Hence, bulk for bulk and weight for weight, the long grass absorbs only half It or less of the quantity of energy that the shorter sward does.

Some grasses and plants, owing to their constitution, are capable of absorbing more .energy from the sun than others; thus we know that ryegrass is better food for stock than, for instance, danthonia, that rape contains more nourishment than silver beet, and we know, too, that a darkgreen plant is, as a rule, more valuable as a fodder than a light-green one of similar yariety. It is for the analyst to tell us what quality it is in one plant which enables it to absorb more from the sunlight than can its fellow, but we know from practical experience that phosphorus, or, as we use it in chemical manures, phosphoric acid, adds to the plant's ability in this direction, for the foliage of grass that is thus manured is a deep green and is mere relished by stock. Convincing Demonstrations. •

We have long recognised that oats grown on light land make more valuable chaff than the same variety grown on heavy, rich land. If the quality of the soil 'or the moisture content were responsible for the chaff's nutritive value the reverse should be the case, but when we realise that the shorter oat crop, grown on poor land which does not contain the mineral elements or moisture to

encourage rank, growth, is more readily penetrated by the sun, so that the whole plant is vitalised and not the top few inches only, we can understand why a light crop makes better chaff than a heavy

crop. Instances demonstrating the food value of sunlight could bo endlessly enumerated, as we have all. nature to draw on in our comparisons, but in an article such as this only a few will be given to suggest lines of thought to, the intelligent farmer and we will then pass on to the practical application of the knowledge that sunshine is food.

We know that the best and sweetest, kjue., the most nourishing, as flavour and | are inseparable, mutton is to 'be found in sheep which habitually graze on the mountain tops. The reason, of course, is that in those situations; the grass is not only short and therefore easily penetrated by the sun, but such altitudes are bathed in sunlight for a jflong period each day while the valleys iand hillsides are in the shadows. We jjiknow that grass grown in the shade of Jj&a plantation, though sappy and luxuriant, '.••Vis neglected by stock in favour,of shorter ■'i-'grass of similar variety in the open field, fUeven though the latter may be much more to obtain. We know that stock "Or do " better in a dry,, i.e., a sunsihiny '{"climate than in a wet, although twice as much visible feed may be available in , the latter. It is evident, too, that this nutriment, first of all absorbed by the plant, is passed on to the grazing animals and through their flesh to man, hence, as food value, stock grazed on sunny slopes where the grass is short, provido more sustenance for man than the same sheep fattened on rank pasture. * Practical Application to Grasses. / 'All this knowledge is of little use unless we can apply it in our everyday fanning to produce grass and crops of • double the nutritive value. We will suppose, in the first instance, that the farmer has decided to close up a paddock for hay. Believing that nour-» isliment is only absorbed by the whole plant, so long as all its foliage is penetrated by the sunlight, he would cut his first crop for hay when the grass had reached, say, four to five inches in length. According to my argument, backed by the findings of the Cambridge experimenters, this crop :of hay would be equal in nutritive value to double the weight of hay taken oft' the same pasture when it had been allowed to grow to the length usual for haymaking. As this first cut necessarily be taken off the land ■wmiA t^lo E P r ' n 3 a • further growth •possiw!? anc ' again a second, and taken f rri a ' cufc °* hay would be In focv? B i same an d in one season, should h Q °* these crops the usual wav cro P matured m •were taken mwwe'° e ' EU PP osin g three cuts ing the soil ui year >'without deplettake from two famer would .in- times the profit, from hk field.