MILK PRODUCTION

Otago Witness, Issue 2545, 24 December 1902, Page 6

MILK PRODUCTION

Notwithstanding all the progress that has been made in the direction of Scientific re> search in agricultural and dairying matters during recent years, there are still quite a large number of problems regarding which A great de-al remains very much unknown. One of these is the much-debated question of how milk is secreted. Even the most profound ecj^isUsis eaojiot x& sa.'istat.t'jr^'-' *9-

eounTTfor tße'pfdcess so familiarly Tmown as the secretion, of mil&. Up to 1840 it was generally taught and believed that milk was secreted or merely filtered from the blood through the milk gland 3. At the present time this theory is not accepted, as it has been shown that as neither casein nor milk sugar are found in tho blood, consequently they could not bo filtered_from it, but are probably the result of a special cell activity. Fat, thoug-h found in tho blood, is not there in sufficient quantity to supply the fat of tho milk, and, accordingly, many eminent scientists have- come to the conclusion that "The milk-sugar, casein, and fats are all formed by the direct activity of the epithelial cells as a result of the decomposition of their protoplasmic (first formed) contents, or their action on the food constituents in the blood. The constituents of ihe milk, the water and salts, evidently result from a direct- process of transudation from the blood, with the exception that without doubt a certain percontage of the potassium salt? and phosphates, like the specific milk constituents, origiuate in the metamorphosis (change^ of the protoplasm (first matter) of the secretory cells." Another thing that has puzzled scientists ia the influence which feeding has on milk. If it were Irue that milk is merely filtered from the blood, , there would not be any difficult}' in. ohanging its richness by changes in feed, 'but it is a well-established fact that the quality of oovra' milk is a natural characteristic, 'something that is born with her, lik« the- colour of * her hair, and all careful experiments show, thib solong as you give- a cow sufficient nutriment, changes \n feed will hot perceptibly influence any one of these peculiarities. The c-tfe-ots of some feeds, however, can b© plainly noticed in the butter fat of milk — i "full giass" butter is decidedly different in flavour and in texture from (that which the same jows manufacture from hay and grain. It is also a well-recognised fact that cotton seed meal, when fed to cows, will- influence the hardness of their butter, and clover hay can be depended on to increase its yellow , colour, but it is doubtful if anyone knows why it is that the colour of butter fat from different oow3 will vary so much as it does, even when they all receive- the same feed. The frequency with which experiments are made with the object of ascertaining the influence of foods upon the yield and the quality of milk indicates the uncertainty which exists in -the minds of practitioners, although it usually happens that when any statement is made t-c the effect that thS | quality of milk is npt influenced by the ration an animal receives, statements which I are deemed to be conclusive of the contrary are immediately forthcoming. Prima facie it would appear that where a herd of cows are changed from one pasture to another with immediately perceptible results in the quantity or quality of the milk, these results were directly attributable to the change, of food, but in making an investiga.-' tion the trained man -by no means accepts such an indication' as conclusive. It has been_ repeatedly shown .that -the quality; of the milk of a herd does ' not practically yary from, day—to- da.jrr In the testa which were conducted with herds of cows during five years at the Agricultural Station at Michigan and at the Geneva Station, in New York State, it was found that the quality of milk of a heifer is practically unaltered as a mature cow, that the quantity of her milk during the first month of the period of lactation changes but little, until, she commences to diminish her flow towards the end of that period, and that there is equally little difference between the quality of the milk when the cows are atr grass and when they are fed on a winter ration. These are net particular, but general jonclusions derived from individual cows. That there are marked changes in the produce of individual cows from time to time, and occasionally with particular herds, must be admitted. Such changes may occur when a herd is turned out of the cattle house in which the cows have been fed upon a winter ration on to a rich and abundant pasture, and also when, owing to excessive heat and (bought, the herbage fails to furnish the animals with suflacien.t nutriment to enable them to produce their normal milk yield." In one case the fat percentage of the milk niay temporarily increase, and in tho other temeporanly decrease ; but these facts tend to prove that food has practically no in- j fluence on quality, but that under varying | conditions cows are able to produce similar i quantities of fat from day to day. The in- [ crease of the fat percentage at ihe end i of the period of lactation, or owing to other , temporary causes, is almost invariably accompanied by a decrease in the quantity , of milk, but fhat increase is not permanent, j And we may take 1 it that if food could < permanently- increase the fat percentage cf an animal, we ought long vgo to havp brought up the ordinary cows of the country to a level with the Jersey and. th& Guernsey, whereas by no process known, excepting selection, could any breed of cattle be raised to this' position. - Like others of the improved breeds of cattle, the _ shorthorn was evolved by selection, very 'properly accompanied by sloilful feeding, but it was not the food which produced tho type, and, for the same reason, it may be :laimed that it is not the food which provides the cow with the peculiarly physical powei to produce a large yield, or to provide milk of exceptional quality. The scrub cow with a contracted udd&r cannot be expected to fill the pail ; she is not physically capable, and her physical incapability has been transmitted from her ancestors — it Las not been produced by feeding. No one knows, but it can jcarc&ly be doubted that the power to produce milk containing an unusual quantity of fat is equally nving to a physical cause, a cause which is inherited. There can be no more reason to doubt this than that » shorthorn, a Hereford, and an Angus inherits its capacity to produce beef and to lay on in excess of fat when skilfully fed. Cattle of the beefmaking breeds are in all conscience fed sufficiently high for any purpose, and if high feeding were conducive to 'milk production it is more than probable that their milk-producing capacity would long since have been improved. But taking the popular types of these breeds as a whole, they are the most inferior milkers in the country, possessing more 01 less contracted udders, and in many cases failing to satisfy their own :alves, It is at the same time true — and the fact cannot be too strongly impressed upon dairy farmers — that among shorthorns there are milking families, but this faot is a witness to the truth of the belief that milking powers are inherited, and neither created nor assisted in any appreciable degree- by abundant feeding on foods rich in fatty :onstituent3. The subject has been widely and most carefully investigated, and though evidence is still wasting as to the exact role in the

system of some prominent constituents *oT~ food stuffs, the- results, of experiments con- "- ducted with, the object of testing the -influence of food* rich in fat constituents on " the quality of the milk production" are of importance. The German experimenter; Hageman, fed cows during six periods on a basis of hay, straw, and beet residue, adding in different periods malt spruts, peanut meal, cocoa-shells, linseed meal, maize cake meal, and in 'two cases sesame oil. The> quantity of fat in eaoh ration varied, and account was taken of the natural shrinkage of the milk with advanced lactation. What was the result? There was 'no indication that fat in the ration, affected the production of fat in the food. The milk during the fourth period was poorest <■ in fat, and yet in tfcat period "the cows." digested the largest amounti -of fait. During 'the third period^ the rations contained considerably less fat, but the niilkl was richer,, and contained the largest tota-1 amount. Durincr^ the second period the milk contained the highest percentage as well as the largesi total yield, and yet the fat in the ration.^ was almost exacily what is. usually rfcoom-; - mended on the basis of the experiments of '- Wolff— o.4lb per 10001b cow ; indeed, in this case the iood was the poorest in fat of any. When die farmer seeks, to Jtoprove the rations by'.the- addition fatty^ foods,. liSse- linssed cake, this evidence goes" :t&: t& r 1 show that he has .-spenf more"; tlian ■ lte\ i? > justified in practically;- obtaining: a - sinral*-'-,-taneously-loss valuable result. -"' "^ *'-'-'" Another case may be -quoted; -A£ the r -Experiaaental Farm of -Lauchstadfe^ Messrs ' Albert and Maorcker^ have r been- studying-"'' ■ the ftf lit* in the ration. "ofTthe ' > cow, using 10 " animals during a period - of* four months. In this -case the ration chiefly. 1 j consisted of sugar-beet, hay, . and straw, the concentrated foods added being bran, cotton seed meal, and rape cake in the preparatory stages. Subsequently paltnnut cake-" and* cocoanut cake- were provided- in substitu- ' tipn of part of the previous' foods, the v highest quantity of fat given during any. period being 1.71b per 10001b 1 cow. or fourtimes as much as that provided in tho-: most successful ease quojred above. It-should,' perhaps, be mentioned that Wolff's teaching'" is- to the effect that, for a maintenance"ration, a cow should receive 15.41b of di- " gestive dry matter daily, of- which 0.41b should be fat — the ration providing sufficient food" for a cow weighing 10001b — each pound beyond 15.41b being sufficient- to produce a. " gallon of milk, of course, within' the cow's j capacity. The results of this very complete* I experiment are marked. Tht- oil cakes in- ". creased the fat percentage of the -milt to ; a>~ definite, but slight, extent, but, as the ex- " perimenters remark, the- increase in the fa*.contend is almost without effect on the totaL amount of fat, and "may- result m financial loss" ; and they recommend 'thai "•the use- of large quantities of - expensivefoods rich in fat should, .be avoided, sincethe possibility of a one-sided increase; of--tho fat -content (by percentage) may leUd to a positive- loss." In this case .the v-extra..-fat consumed wae-.-apparentljT not' lostV for,"" according to t-he weights 'of "the cows, it.wa3. used; for- the^pnTduction -of^body-;fat.--IPh&'' feeding, left, some of the> cows ;over-f at, and . unfit!, for • anything' but the" butcher, • and. curious to relate, the experimenters believed that the results suggest a , possible method for rapidly fattening dry cows. The figures and particulars given relating - to these Lauohstadt experiments are instruc- - tive. During the preparatory stage Ahe^ average yield of ntilk per cow- was 17.2 kilos. This fell in the second period to 16.8; when fed on the first rich ration it ■ -fell again to 16.2; and on the poor ration to 15.3. Where the next ration was'- pro-, vided rich' in fat there was a further fall--to 14.6. and again on the next rich ration to - 12.4. The last ration was poor in fat, -and- i then there was an inorease to 13.4 kilos, so:>v that, -taking the whole period, the rich" rations appear to have had an influencecontrary to that which was -expected. Then, ' as to the fat percentages. During, thefirst--two periods, which were preparatory, theaverage was 3.02 and 3.21. /The rich ration. • followed, when the fat rose to 3.5, • falling' under the poorer ration to 3.2, increasing •■ under the still richer rations with smaller; milk yields to 3.4 and 3.9, and falling aaaih. under the last and poor ration to 3.1. These^ fat percentages accompanied by. total j yields of fat which varied chiefly in accordI ance with the milk yield. There wrts a- "- i diminishing yield durin* the whole of hhp | four months, whatever the 'ration, excepting 1 i that with the last ration, which was poosr-in , fat, there was a slight increase over the one previously given, but the total- fat produce j , increased until the first poor ration was j given, when it felt, remaining practicallyi the same until the last ration was given,when it fell considerably.-" 'ThTede facts, • without protfin'g that fat ' has. no . influence" in feeding for milk • production witk regard, to quality, clearly do- prove that' the *ya- '• flunnce was very alight. • / The experiments conducted at'Rothamstedi 1 ' for matey years "on "The Feeding of- Ahimaja • for the .Production .cf Meat, Milk* and - Manure, l and ' for." the Exercise 'of Forced' ' very clearly demonstrates thai, whilst <*f - the nitrogenous substances of the food, the amount stored up in th» fattening increase of an ox will be only 1.131b, the amount " carried off as suoh in the milk would be 6.61b, ,or nearly six times as mucs, -Of mineral matter again, whilst the fattening 1 increase would only require- about . 0.221b, the milk would carry off 1.351b. Of fat. however, whilst the fattening increase would • contain 9.531b, the milk would contain, only. 6.331b, only two-thirds- as much. On-the other ■ hand whilst the fattening increase contains no other non-nitrogenous substance than fafc.the~ milk would carry off 8.321b in the form of ; milk sugar. From the -foregoing comparison, it is evident that the drain upon the food is x very- much greater for the production of milk than for that of meat. This isespecially the case in the important item of - nitrogenous substance; and if, as is frequently assumed, the butter fat of the milk is, at anyrate, largely derived from the nitrogenous substance of the food, so far as is so, at least two parts of such substance* would be required to produce one of fat. Thua. as compared with fattening increase,which may in -a sense be said to be little* more than an accumulation of reserve material from excess of food, milk is a special product, of a special gland, foi a. special normal exgency of the animal. . Further, the Eothamsted authorities advised :— "Whilst common experience shows that the herbivorous animal becomes the more fat, the more, within certain limits,

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