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NUTRITIONAL TROUBLES IN STOCK
Dr. H. G. BELSCHNER (Senior Veterinary Surgeon), Department of Agriculture, Sydney.
Probably the majority of the disorders which affect stock in this State are associated directly or indirectly with feeding and management. As Inspectors of Stock you are concerned more with the prevention of disease than in curing disease, and the preservation of health is intimately bound up with the question of feed.
With the exception perhaps of losses from drought and the effects of sheep blowfly, diseases of dietetic origin are responsible for the greatest losses amongst sheep. Further, there is a considerable loss to the industry in productivity through malnutrition. A sheep cannot be in perfect health and produce a maximum amount of wool if the diet is deficient as it not infrequently is. Sometimes an overabundant diet is responsible for ill-health or is a contributing factor to certain diseases. The question of feeding of stock in relation to disease is, therefore, often wrapped up with management.
It would appear that in concentrating on improving the breed of sheep, pastoralists have rather neglected to give sufficient attention to the problem of feeding. The wonderful natural resources in the soil of a new country, aided by periodical droughts, have alone been responsible for maintaining the chemical composition of our common grasses and herbage plants, necessary for maintaining stock in good health. It is the Chief Veterinary Surgeon's wish that you all become feed conscious (see circular D. 36/17).
There is a considerable amount of educational work to be done in connection with the feeding of stock and, as you have no doubt also noted, there is an increased demand from stockowners for information on the subject. You are the people to convey to the pastoralist this information, and hence a responsibility rests on your shoulders to learn all you can of experimental work which has been carried out and to make yourself familiar with the latest discoveries, so that you may be the personal bearers of the information to the man on the property.
At an International Veterinary Congress held in London a few years ago, a prominent scientist, speaking on "The Scientific Feeding of Animals," stated that "The practice of the feeding of domesticated animals was susceptible of many Improvements which arose out of scientific progress. It seemed that only the laboratory, by its method of biological analyses, could add new knowledge on the subject. Rational feeding on a scientific basis was one of the essential factors for the health of domesticated animals."
Sufficient attention is not paid by stockowners to the variety of feed with which their stock are supplied, and owners are usually satisfied provided they see a good growth of feed in their paddocks, Irrespective of the fact that it may chiefly be the one class of feed.
All animals must have a variety of food if the body is to be supplied with a well balanced ration. It is here that overstocking and bad managemet in the past have done so much harm. Many of our finest and best grasses have been eaten right out and prevented from seeding. The more hardy and frequently more indigestible and innutritious grasses, however, remain.
We know that the nutritive value of the pasture plants is at the maximum at a certain period of growth, after which they deteriorate. The question of supplementary feeding of sheep is now receiving a certain amount of attention, and owners who have adopted same are enthusiastic in the results obtained by improvement in body and wool weight of their sheep. The benefits resulting in the control Of internal parasites in stock have also been observed.
Whilst at present supplementary feeding mainly consists in feeding wheaten or oaten chaff, and sometimes grain or lucerne hay to stock, attention in the future will be given to cutting of meadow hay and conserving it, to be subsequently fed to sheep and cattle during the periods of the year when the nutritive value of the pasture is low.
Supplementary feeding is largely a matter of cost, and therefore attention must be given to the utilising of feed stuffs which can be grown on the property. In the farming districts cereal hay may be grown solely for stock feed. In those areas of the State where the rainfall is low and farming is not usually carried out, the conservation of fodder is more difficult. You have, however, all seen hundreds of thousands of acres of beautiful meadow hay in the form of grass or herbage going to waste, or at least only a portion of same being eaten by stock when it is at its maximum value. Much of this might be cut and conserved, not only for use in times of drought but during average seasons.
We hear a lot about the necessity of minerals for stock, especially from people interested in proprietary salt ticks. Some of the statements made are correct, many are exaggerated statements. Under ordinary conditions on good pasture, sheep obtain all the minerals they require from the natural grasses and herbage. The soils of some districts in New South Wales are deficient in certain minerals, the chief of which are calcium (lime) and phosphorous (phosphoric acid, P2O3).
It is not necessary for me to remind you of the importance of calcium and phosphorus for the correct functioning of the animal body. You know the outstanding disease conditions resulting from a lack of these minerals, namely rickets and osteomalacia, but perhaps have not realised that the mineral content of the diet or food consumed has a more generally important effect on the health of animals and that serious losses occur when there are marked deficiencies or excesses of minerals.
There is a disease similar to Toxaemia of Pregnancy, which has been called "lambing sickness" or "milk fever." It has been shown that the disease is caused by a calcium deficiency in the blood (as is the case with milk fever in the cow). Affected ewes respond to a 10 per cent. calcium chloride solution into the jugular vein, and also to udder inflation as with the cow. The prevention of the disease consists in correct feeding prior to lambing and having available to the ewes in covered troughs a supply of sterilised bone meal or dicalcic phosphate.
Before referring more specifically to a few of the diseases in stock associated with nutrition, a few words concerning salt licks might he said here. The Department's recommendations, based on wide observations by its officers, are very simple: Salt and sterilised bone meal or di-calcic phosphate made available to sheep and cattle separately in covered troughs, or mixed if more convenient to put out this way, usually in the proportion of 50 per cent. of each is all that is recommended. A little molasses water may be added to hold the lick together and prevent it from blowing away.
The mineral requirements of sheep vary according to the country, pasturage and age of the animals. The only minerals, however, likely to be required are sodium chloride (salt), calcium and phosphorus. The latter two are available in sterilised bone meal or di-calcic phosphate. If the lick is mixed, the sheep may have to eat too much of one ingredient to obtain sufficient of the other.
It is most undesirable to add large quantities of molasses or other feeds to licks to make them attractive to stock. If stock need minerals, they will eat the lick without any addition to same.
Sulphur, potassium iodide (Iodine), manganese,etc., are not generally necessary for incorporation in salt licks in this State.
Concerning the respective merits of di-calcide phosphate and sterilised bone meal, it is pointed out that both are good. Di-calcic phosphate, which is prepared from rock phosphates chemically treated so that it contains little of the impurities found in raw rock phosphate, is considered to be more assimilable than bone meal (3 to 1), and therefore less is required. On the other hand, bone meal is less finely powdered than di-calcic phosphate and loss is not so likely to be experienced when placed out in troughs in the paddocks. Dicalcic phosphate contains about 40% P2O3 about 25% P2O3.
Salt, known commercially as sheep salt or stock salt is the cheapest salt available, and is suitable for all classes of stock (about £3 per ton). Rock salt is very expensive (about £7 per ton), as it is imported, and whilst it is in a convenient form, especially for making salt available to horses, the expense is hardly justifiable.
The question of the value of Glauber or Epsom salts mixed with salt during dry periods has been frequently discussed. It is very doubtful whether the amount of these salts as is usually mixed in a lick has much laxative effect on sheep or cattle.
It would be more advantageous to feed molasses to stock during dry periods on account both of its feed value and laxative action, but this should preferably be spread over hay or chaff or fed in block form. It should not be added in any great quantities to a salt lick, otherwise the sheep may eat too much salt, which may have an ill-effect. If added to a salt lick, 5 parts to 100 parts of lick is sufficient, and it should be broken down with water and poured over the lick and thoroughly mixed.
DISEASES OF DIETETIC ORIGIN.
Time will only permit of reference to a few of the diseases of dietetic origin. Amongst those which come to mind are:—
(1) Toxaemia of Pregnancy in Ewes.
This is a nutritional disease associated with pregnancy. It occurs in the pregnant ewe shortly before lambing, and those ewes carrying twin lambs are most likely to be affected. The actual cause of the disease is still not definitely known, in spite of much research work which has been carried out. The indirect causes, and which, in the light of further knowledge may later by referred to as predisposing causes. are:
(a) A set-back in condition towards the end of pregnancy, either sudden or gradual;
(b) Over-fatness and lack of exercise.
Just recently there has been a good deal of pregnancy disease in the West, where the pasturage has been depleted by grasshoppers and drought conditions have prevailed. Conversely, this disease is not infrequently seen in ewes on rich feed in the more closely settled districts.
A good deal can be done to prevent the disease by maintaining the ewes in good, but not over-fat, condition throughout the period of pregnancy. To do this it may frequently be necessary to adopt supplementary feeding to maintain the protein content of the feed supply. Quite recently in the West, a recommendation was made that hay and ensilage, which was available, be fed to the in-lamb ewes for the reason that the pastures were then very dry and little trefoil burr was available on the ground. The Manager of the property protested, stating that there was plenty of time to start hand-feeding, as there was a fair amount of dry food available. Some six weeks later, Just prior to lambing commencing, the ensilage pits were opened and ensilage and hay carted out to the sheep. The feeding, however, was commenced too late, and considerable mortality is now occurring from Toxaemia of Pregnancy.
It is dfficult to make pastoralists realise the difference between supplementary feeding and hand-feeding. It is so very important with ewes in lamb that they should not suffer any check.
Where Toxaemia of Pregnancy occurs as a result of over-feeding, the trouble may be checked by gently exercising the ewes daily or allowing them the run of a rough paddock. They should not be suddenly changed from their good pasture to a poor pasture.
It will be seen that the essentials in prevention are wrapped up in good animal husbandry. The indications are that rational management should be practised throughout the whole of the in-lamb period. The ewes should be kept in good condition by judicious feeding and not allowed to become over-fat, or to suffer as a result of malnutrition.
(2) Entero-toxaemia.
In recent years much attention has been paid to this disease, which affects both lambs and mature sheep. You will remember that not so very long ago Pulpy kidney disease in lambs or "Plethoric toxaemia" as it was sometimes called, was considered to be purely a dietetic disease. As a result of considerable research work. this disease and mortalities amongst grown sheep attributed to other causes were found to be caused by the multiplication of an organism (Bacillus Ovitoxicus) within the small intestines and the production of a toxin, resulting in a toxaemia and frequently the death of the animal. The factors responsible for the proliferation of B. Ovitoxicus in the contents of the small bowel are stasis or sluggishness in the bowel action brought about by the type of feed upon which the sheep have been grazing, or as a result of lack of exercise. The discovery that the disease is caused by a particular organism has allowed of the production of a vaccine which, of course, has helped considerably in preventing the disease. It must, however, not be lost sight of that certain pastoral conditions and types of feed favour the disease and that quite often much can be done to prevent the disease by good animal husbandry. In certain seasons of high rainfall with a big growth of very soft feed, not so much can be done in this regard.
The late Dr. GiIruth was of the opinion that the disease which he had observed among sheep running on turnip crops in New Zealand was entero-toxaemia, and he had noted that the disease could be checked when the sheep were allowed to have the run of natural rough pasturage in addition to the turnips, or when hay or straw was made available to the sheep. In this country we have frequently seen mortalities among sheep on growing crops (wheat and oats) which we now know is mostly due to entero-toxaemia.
Much can be done to prevent these mortalities on growing crops and other succulent feed by feeding fodders rich in fibre in the form of hay or even rough grass, to stimulate peristalsis of the bowels. Where there is good bowel action, the stasis which permits of the development of B. Ovitoxicus does not occur. Even the supplementary feeding of chaff in self-feeders has a beneficial effect on the incidence of the disease.
It is considered that more attention should be paid to the control of entero-toxaemia by feeding, because even if not solely relied on, it is a valuable adjunct to vaccination.
(3) Nutrition in relation to Parasitic Infestation.
It has been demonstrated over and over again that adequate nutrition by good feeding is the most satisfactory way of controlling internal parasites of both sheep and cattle. This immediately brings up the question of supplementary feeding.
In England, sheep, on the average, harbour a far greater number of internal parasites than do our sheep, but the losses are not heavy. Further, the English sheep are almost exclusively mutton sheep, and have to be fattened quickly. The reason they do not exhibit to any great extent the usual effects of high infestation with internal parasites is because they are so well fed.
The majority of the internal parasites of sheep are not blood-suckers. They live on the partly digested food of the host. Consequently, if the feed supply is sufficient for both the animal and the parasites, the former shows little effect. There are certain other factors involved. Unfortunately, many stockowners do not realise what an adequate natural pasture is, and are very surprised when told that the natural feed is inadequate for their stock and an important contributory factor to the trouble they are experiencing with worms in their sheep. A great sward of grass, much of it dry, may be adequate feed for wethers and perhaps dry ewes, but would be quite unsuitable for weaners. The latter will do much better on a much shorter pasture containing a green shoot. In any case, through-out a considerable portion of the State, wherever Trichostrongylosis is experienced (and there are not many parts where this trouble does not occur), some additional feeding to the natural pasturage is usually required for the weaners. How many pastoralists adopt the practice? Adequate and proper feeding of the weaners is essential. notwithstanding whatever treatment in the way of drenching may be at the same time given.
As applied to large holdings, supplementary feeding should be interpreted in its widest meaning, to include rotation of paddocks, top dressing and renovation of pastures, and the sowing of fodder crops. This for the reason that by all these means the nutritional requirements of sheep and other animals may be adequately supplied. Worm infestation is always more serious in improperly nourished animals.
On smaller holdings, supplementary feeding of sheep, particularly the weaners, with chaff and oats in self-feeders is a most commendable practice, and is now being carried out economically by many men. During last year several articles on supplementary feeding of sheep, with particulars of self-feeding troughs, the cost, and some results obtained, were published in the Agricultural Gazette. These articles are available as reprints should you require them.
It is desired, however, to give you an example of the value of supplementary feeding in the control of internal parasites from an experiment carried out by Mr. Max Henry, at Glen lanes, in 1910: A number of lambs were taken which were known to be worm-infested. They were divided into five (5) groups.
Lot 1 received no drench, but was supplied with additional feed to the natural pastures. The feed given to these sheep consisted of lucerne and various other introduced grasses of high feeding value.
Lot 2 drenched six times with arsenic drench.
Lot 3 supplied with licks.
Lot 4 supplied with licks and drenched three times.
Lot 5. No treatment and fed on natural pasture.
In the case of lambs fed on introduced grasses and lucerne, the average increase in weight during the experiment was 62 pounds. Those (trenched each month, 28 pounds; those on licks, 271 pounds; those on licks and drenched, 27 pounds: those receiving no treatment and on natural pasture only gained 21 pounds.
The experiment was conducted from January to September, and the lambs were six weeks old at the commencement of the test.
If the weight increase and soundness of the wool are considered, it will be seen that worm infestation, even to a considerable extent, is practically harmless as long as the food supply is abundant and nourishing.
Many other trials have since been conducted which only confirm these earlier findings of Mr. Henry. An instance is known where a man fed two ounces of maize per head per day to portion of a mob of young wormy wethers, and without drenching overcame the worm trouble in these sheep. Other sheep in the same mob and running in the same paddock, but which did not receive the supplementary ration, succumbed to the effects of parasitic infestation.