THE FEEDING OF LIVE-STOCK.

New Zealand Journal of Agriculture, Volume XXXVI, Issue 2, 20 February 1928, Page 82

THE FEEDING OF LIVE-STOCK.

J. McLinden,

M.R.C.V.S., N.D.A., Officer in Charge, Animal Husbandry

Branch, Live-stock Division.

II. UTILIZATION OF NUTRIENTS.

A great number of complex processes are involved in the nutrition of stock during the assimilation of the foodstuffs digested by the animal. These processes will be dealt with here under two heads — maintenance and production. By maintenance is meant the keeping of an animal on a constant planeneither gaining nor losing, but simply replacing . tissues which have been used or depleted. By production, on the other hand, is meant work, fattening, growth of frame, milk-yield, wool, and so on. These definitions may not be scientifically accurate, but from the practical standpoint of animalfeeding they define the two heads completely. FATTENING. Fattening is an easily recognized process, being merely the conversion of farm food-products into fat. . So far as the dairy-farmer is concerned, this process applies more to pigs than to the dairy stock. But' the dairy stock should be brought up into good condition before calving. If this is done - the cow has every chance of doing well, and if she should be of a deep-milking strain she will utilize her condition and even more, for she will even draw on her body reserves. This is a peculiarity of the dairy cow which cannot be overlooked—the fact that she will produce milk although she is not being fed sufficiently, doing so at the expense of her own body. Fattening may take place at any age, especially if the foods be of a fattening nature and fed in liberal amounts. It goes' on most rapidly after maturity, when there is a greater surplus of food materials available after the maintenance requirements of the body have been met. Fattening, therefore, in the main is - determined by the amount of food which the animal can digest in excess of that required for growth and production, such as milk or wool.

GROWTH.

The importance of growth is not always well realized. It is one of the most essential points in animal husbandry to feed the young stock well, and allow them to develop. Too many failures in the dairy herd can be attributed to 'this cause, the young animals being poorly fed while in their youth—say, up to the end of their first lactation. In the case of pigs this often occurs after weaning until fattening commences. Heifers in calf especially must be well fed, for they are growing themselves and developing a foetus at the same time, and when the calf is born they are milking. These functions cause a ’ very severe strain, and must therefore be supported by liberal feeding. It is impossible for heifers and young cows to grow and produce milk on a small food-supply, and it is no economy to stint them at . this age. Certainly one sometimes finds very good milkers which were not well fed in their youth, but their output is at the expense of growth. If they had been properly developed they would have been deeper and more economical producers. An inherent ability to milk will always show. Growth takes place from birth to maturity, and consists essentially in an increase in the protein tissues of the body and the bonestructure. Developing at the same time is an accumulation of body-fat, which will vary according to the type of food eaten. Flesh-production may be modified by food to a limited extent, but it appears to be mainly a function of the animal, being determined by breed and individuality. Growth is most active in the young, and diminishes as the animal grows older, until at maturity it practically ceases.

FOETAL DEVELOPMENT.

The exact food requirements of pregnant stock are not known. But if the mother is not well fed she will nourish the foetus at the expense of her own body. This will reflect adversely, of course, on her milk-supply —resulting, with pigs, in a poor litter at weaningtime, and, with the dairy cow, in poor production.

MILK-PRODUCTION.

By this is meant the production of the dairy cow for the . food supplied to her. It is not sufficient to merely maintain her : it is from the extra food eaten that the returns of the farm are going to come. Specially important is it that food be given in accordance .with production. There is no more efficient converter of food into milk than a deep-milking cow. Milk - production gives the greatest returns-in value from an economical point of view. Why it should be so —the physiological reasonis not yet known, but the fact remains. It is easy to understand why nature makes milk-production an economical process, but it is difficult to know how it is done.

The principal factors which influence the amount and quality of a cow’s milk are breed, individuality, age, frequency of milking, condition, excitement, climatic conditions, and the amount and kind of food. Only a few remarks are required to explain these factors, but two will be taken —namely, condition, and the amount and kind of food. The physical conditions as mentioned influence the

quality and quantity of the secretion of cow’s milk. An animal in good condition will give more milk, and of better quality, than an animal in poor condition. It has been shown that cows in good condition, after parturition will give richer milk throughout the lactation than those which are in poor condition at its commencement. Influence of 'Food on Quality of Milk. Until quite recently the general opinion of the majority of dairyfarmers was . that the feed influenced the quality of " the secretion. This is not so. Provided the cow receives sufficient food to maintain her weight, no increase of food will influence the quality of her milk. No single food or combination of foods can alter quality if, to start with, the animal is receiving sufficient to meet her requirements. Certainly, if underfed cows. are given a liberal ration they will respond to such treatment; the ration, if carrying a liberal supply of protein, will stimulate any cow to the maximum of productivity. But no. amount of feeding, however rich and liberal, will alter the composition of, say, Friesian-breed milk to that of Jerseymilk in test. This, of course, does not mean total butterfat, but butterfat percentage. Influence on Quantity of Milk. The food consumed influences very markedly the quantity of milk . secreted -by a cow. The food is the all-important factor in the management of the dairy cow, and it is the dairy-farmer’s business to provide her with the quantity and quality she requires so that he will receive her maximum production. Heavy eaters of dairy type are those which give the largest yields most economically. In a test which was made the heavy producers returned 52 per cent, over cost of production, while the poor producers returned only 20 per cent. Great variations, it will be realized, arise in individuals in the matter of economical use of food, but the phenomenon previously alluded to holds good. Any cow, of no matter what dairy breed, will produce milk even although she is not being supplied with the necessary food. ' This point has already been stressed and is here repeated, for it would seem to be ignored, or possibly not sufficiently recognized, by farmers who do not pay sufficient attention to subsidiary feeding during the periods of poor grazing. If a cow produces at the expense of her own body, this loss must be replaced at once if possible, but the endeavour should be never to let the loss occur at all. If the cow does suffer in condition through a heavy lactation and it is not possible to guard against it at the time, then judicious and heavy feeding should be practised when supplementary crops are available. - Experience is going to show that these depletions, due to deep milking, are a very important causative factor in the many ailments now affecting our dairy herds. The necessary feeding does not mean only those substances already described as the protein, carbohydrates, and fats, but also the minerals, such as calcium, phosphorus, and potash. Just as these are essential to the pastureas experience has taught—so are they essential to live-stock. Investigators, for instance, now find that as the calcium content of the blood is reduced the incidence of milk-fever increases, and vice versa. The heavy-milking dairy cow must have complete and sufficient feeding.

Again, how often is it told that a certain sow is an extremely fine mother because her litter pulls her down extremely in condition. But if this can be regarded as proof of her quality it certainly can be taken as proof of the owner’s inability to realize his duty to such a sow. Where litters are taken off the breeding-sow once a year the damage done by such management will not be so readily detected, but where the breeding is done twice yearly it very soon results in small litters, too high a percentage of deaths before weaning, and sterility in the sow. If strong healthy piglings are to be weaned regularly, then the sow must be well treated and kept in good breeding condition, neither too fat nor too thin. This means liberal' feeding and a plentiful supply of good drinking-water, together with room for plenty of exercise. < VALUE OF NUTRIENTS. It is essential, before proceeding further, to discuss some standard whereby the values of the nutritive materials in a food may be compared. Digestibility : It is common knowledge that all the food consumed by stock is not utilized by them for sustenance and production. As the food passes through the digestive tract a certain portion of it is prepared by the animal for assimilation. - That is known as the digestible portion, and is chiefly composed of digestible protein, carbohydrate, and fat. It is this portion which is of feeding’ and producing value to the animal fed; and when considering the food eaten by an animal it is the digestible portion which most concerns the farmer. Each type of food used is generally digested in similar quantities within close limits. For convenience this quantity digested for each particular food is referred to as the “ coefficient of digestibility.” So far as average farm crops are concerned, no great differences exist in the digestibility of the respective foods. Digestible carbohydrate equivalent : The energy-giving portion of a ration has been described already as the carbohydrates and the fats. For convenience these two substances have been grouped together, and allowance made for the fat to contain two to three times as much energy as a similar quantity of starchy matter. This is calculated, of course, on the digestibility of the carbohydrates. Total digestible nutrients : The meaning of this term should be obvious. It is the value of the digestible protein when added to the digestible carbohydrate equivalent. Nutritive ratio : At one time this term held great significance. When rations were being compiled of concentrated foods it was regarded as essential for proper nutrition that the nutritive ratio should be a definite thing. This nutritive ratio means : the knowledge of the relation of the digestible crude protein to the digestible non-protein constituents in the diet (digestible carbohydrate equivalent). As the quantity of digestible non-protein becomes greater in proportion to the digestible protein the ration is said to become “ wider,” and as it lessens the ration becomes “ narrower.” This is really suitable for the classification of feeding-stuffs; but otherwise, as an index as to the suitability of a ration being adequate to the needs of an animal for a specific purpose, experience has emphasized what was originally felt to be a weakness. At the present day the nutritive ratio of a diet

does not hold the significance which at first it was expected to hold. Better and more suitable guides have been adopted through a better knowledge and understanding of animal nutrition. REQUIREMENTS OF STOCK. . It is important to know the composition of a food arid how much of that food is digestible, but it is just as essential to know what the live-stock require for milk, beef, or pork production. In those countries where natural conditions compel the stock to be fed on substances other than grass, hay, and grain and root crops this knowledge of the composition of foods becomes very necessary, for the subsidiary foods used are generally very expensive, and economy must be practised. But, again, in countries like New Zealand, where it may be said that stock depend wholly on the foods grown on the farm, such knowledge is also very essential from another point of view. Dairy cows require foods which will supply them with an adequate amount of protein if they are to produce their maximum. Heavy production means that greater quantities of mineral matter must be supplied, or the cow will suffer in health. As for the carbohydrate portion, there is little fear of the cow fed on home-grown foods not receiving enough ; but this, unfortunately, cannot be said with regard to the amount of protein fed and also the amount of mineral supplied. * Further, there is an important fact also to be contended with. If the amount of carbohydrates fed should be too much in comparison with the amount of protein (a very likely thing with home-grown crops), then the value of the protein is reduced because it is not digested to the same extent. In other words, excess of starchy foods reduces the digestibility of the protein portion of the diet. The converse a liberal supply of proteinincreases digestibility of all the diet. This factor is referred to as the “ balance of nutrients.” It not only includes the digestible protein and digestible carbohydrate equivalent, but also the ash or mineral portion, the vitamins, and what is described as the “ quality” of the protein. . Quality in this connection refers to the suitability of a protein for maintaining health. Although the different organic constituents can to a very great extent be substituted one for another, protein is absolutely essential for the development of the foetus and milk-production. For such purposes an average amount of protein is shown experimentally to be required. But the figures to be given for the purpose of the ration must be regarded as an average, and do not represent the maximum to be supplied. With milk - production especially it should be, if anything, exceeded, for protein has the effect of stimulating metabolism generally and milk-production especially. As the substance increases the cost of a food, it must be used with care and not fed too lavishly; or the cost of feeding would defeat the object. All the known feeding-standards in use at the present day only take into account the two chief types of organic food, and no attention is paid to the mineral constituents and other accessory factors. The real reason for this is that our knowledge of these other requirements is still at the investigation stage, and not sufficient is known of them yet to permit of detailed requirements being stated. What is known is that. the dairy cow must receive . a full

supply of nutrients if a prolonged and heavy production is required. If this is not supplied, it results in depletion of her own body, resulting in her milking only for a comparatively short period after calving. With pigs it results in their not thriving at the necessary rate consistent with economy in production. A pig of slowly attained maturity is an economic loss. Time must be reduced to a minimum in the production of pork and bacon. What these necessary requirements are for the different kinds of animals, especially milking-cows, is hard to define, because they vary, with age, size, production, Ac. It will be quite" readily understood why the ration for a milkingheifer will vary from that for an adult cow. The milking-heifer is not only producing milk but she is still growing, therefore she will require a more liberal protein and mineral supply.

Tne influence of size of the animal on the ration, is difficult to explain, but experiment has shown that relatively’ the smaller animal requires more protein than the larger one. The effect of condition on the maintenance ration of a cow does not require much explanation. If two animals are compared —one in good and the other in poor condition more nutriment for a given weight will be required for the animal in good condition than for the poor one, especially as regards protein. The pool' animal can be maintained on a cheaper diet on a maintenance ration. At the present day it does not pay to keep animals in poor condition, for their production suffers too severely. Such dairy cows cannot keep up production, and if pigs are allowed to remain poor they cannot be economically fattened. Under present conditions pigs must be kept advancing every’ day from birth till the time they are killed. Failure in this respect is probably the greatest source of lack of success in swine husbandry. NEW ZEALAND NATURAL CONDITIONS. The New Zealand farmer is fortunate in one very’ important respect so far as dairy cows are concerned, and that is in the possession of natural conditions making normally for a great supply of succulent food. These foods have a very good effect on dairy cows, and are essential to economic production. They are a very 7 palatable type of food, laxative in nature, have bulk, and provide water, which is so necessary to dairy cows of deep-milking qualities. Good pasture-grass is the best succulent food for dairy cows, and in late spring and early summer will provide all such feeding they require. For the later part of summer and in autumn it, may be necessary in certain areas to grow auxiliary forage crops or use silage, while in winter-time roots and silage provide the requirement. This type of food should always form part of a dairy 7 cow's ration, for she always does better when the ration is laxative in nature. Here, again, is why hay 7 when used should contain a plentiful proportion of clover. \ When feeding green foods care must be taken with turnips, kale, silage, and the like, otherwise the milk will be tainted. It is much easier to taint the milk than to remove such flavours from it. Such foods should only be allowed after milking. (To be continued.) ■