Winter Feeding of Dairy Cows

New Zealand Journal of Agriculture, Volume 78, Issue 4, 15 April 1949, Page 349

Winter Feeding of Dairy Cows

WINTER feeding of stock is probably the most important part of the dairy farmer’s seasonal operations, for the cows’ production in spring depends on how they are fed in winter. The growing and saving of winter feed in such forms as clover hay, lucerne hay, silage, autumn-saved pasture, roots, chou moellier, and oats have reached dimensions which indicate that all farmers recognise the need for extra winter feed for dairy cows.

MOST farmers know how to budget for winter feed for their herds to suit their own requirements and local conditions within fairly-narrow seasonal limits. However, a few are not wholly conversant with this part of their farming operations, perhaps being new to a’district or just starting dairy farming, and others may wish to change methods which are not standing up to the test of butterfat per acre. In all such cases of doubt the local Instructor in Agriculture should be consulted; he knows local conditions and can give advice on growing and saving feed to suit herd requirements, soil, and climate. The best methods of supplying the feed to the wintering cow are the main concern of this article by W. D. Ross, Veterinarian, Department of Agriculture, Palmerston North. Most Critical Time of Cow's Life The wintering dairy cow is at the most critical time of her life. She has finished a season’s milking, is carrying a calf, and must build up her own body and that of the calf and have a reserve of stamina for the spring. All this must be accomplished on the food she is given in the winter.

The main object is to build up the cow for the best return in the spring and summer. That means, the highest sustained production that can be obtained up to the limit of the cow’s capacity to turn feed into milk. Beyond this limit come the signs of overstrain, slips or non-contagious abortion before calving, and after-calving milk fever, grass staggers, and ketosis, the so-called metabolic diseases. Metabolic diseases are the visible effects when the body can no longer cope with the process of building up feed into, living matter and breaking it down into energy and milk, either because the animal cannot obtain or digest enough feed or because the - body is not in a fit state to utilise the feed provided. Unfortunately, the balance between fitness and unfitness is very fine in a high-producing cow and very little strain may upset it. For an understanding of the whole problem, the high-producing cow must be regarded not as just a machine but as the very highly-specialised product of years of careful breeding, testing, and selection for milk production. Production at Expense of Health The stage has now been reached at which a high producer will milk heavily after calving in response to the

stimulus of calving and the way in which she has been bred, whether feed is sufficient or not. If feed is deficient in either quality or quantity, her body cannot withstand the heavy drain on her reserves of proteins, fats, and minerals; these are soon depleted or out of balance and she falls an early victim of one or more of the metabolic diseases. So strong is this urge to give milk, even at the expense of her own health, that it is quite usual for a well-bred high producer to lose 1001 b. of body weight during the first 2 months of heavy milk production in the spring flush and yet remain normal in health if properly fed. - Highly - developed specialisation makes the cow her own worst enemy and leaves her helpless to ward off the effects of bad management. She cannot merely produce to suit the feed, but must produce in the first, flush even to the stage of endangering her own life. That is contrary to the laws of Nature, and if left to her own devices on rough feed, this type of cow would breed itself out because of slips and deaths in early spring and infertility in late spring and summer, leaving only the low producers. Elimination of the high producer is very evident on the low-average or poor farm where the high producers slip or go down with milk fever, ketosis, and

grass staggers, or go dry after a few weeks, while the rest of the herd goes through the season but gives very poor butterfat returns.

On the other hand, New Zealand’s highly-specialised grasses have evolved to the/ stage at -which more dry feed can be produced from an acre of grass, and therefore more 'food products per unit of labour, than, in any other country in the world. These grasses, if used properly, . are the .finest feed availabe for dairying and 1 can stimulate milk production to.: such ; a degree that the early flush .of £ protein-rich pasture, if fed without good ' hay or roughage, drives the high producer to even greater production, whether, her body balance can withstand the;strain' or not. That again gives . rise ;to metabolic diseases if j the stock are badly managed, and such pasture can be very dangerous in the hands of a careless farmer. \ . Thus, the farmer’s own clever- r ness in evolving the high-produc-ing cow and high-producing grasses has made the co-ordination of cow and grass a very delicate operation. ■ - ? Guides for Winter Feeding Years of careful research work, field experiments, and the practical experience of veterinarians and farmers have established a few broad guides for the winter feeding of the dairy cow. These guides aim to adjust the high producer to the highly-intensive milking plan and the milk-stimulating pastures so that maximum production can be obtained with the minimum of disease. The metabolic diseases cannot be eliminated, as the balance is upset by many unforeseen factors, such as indigestion . and bad weather, but the major predisposing causes can; be largely overcome by following a few simple guides which allow some latitude to suit most conditions of weather and farming.

Cows must be kept at about the same body weight throughout the year, particularly during winter and early spring. In practice it is found better to save feed in autumn, if it is short, and allow cows to fine down a little then, than to have them on short rations immediately before or after calving.

If feed is reduced before calving, the cow’s essential mineral and body resources become depleted and in bad cases heifers and young cows will slip their calves. That is a frequent cause of non-contagious abortion, and in a season when feed is short is very prevalent. However, the older cow carries on to deplete herself thoroughly and is a fit subject for milk fever a few days before or after calving. The calf of such an undernourished heifer or cow often is born dead, or may be alive but small and weak, subject to scours, and very hard to rear into a worth-while animal. These weakly calves are often born about a fortnight before their time.

The underfed cow may come safely through calving and milk for about 6 weeks until the peak of production finds her out and she contracts ketosis because she must use up what body fat she has left for milk production and she receives insufficient sugar-rich foods such as mature grass, hay, or molasses to burn the fats up completely, leaving excess ketones circulat-

ing in her bloodstream. She becomes a “dopy,” , rough-coated wreck and practically goes out of production if not treated with plenty of molasses, good feed, and extra minerals. ' ' At about tb „ camp nr bftob o At about the same time, 01 often a week or two earlier, cows underfed in winter or suddenly changed from a good diet of hay and young grass to young grass alone are very subject to grass staggers. In this condition magnesium salts are short in the bloodstream, and one of the magnesium salts, usually Epsom-salt, has to be used to make up the deficiency. It can be given by the mouth in a mild case and injected under the skin or into a vein in a bad case. In some districts Epsom-salt is added to the drinking water. Deaths are very common in grass staggers cases if they are not treated in time, and again the high producer short fed in winter suffers most. Grass staggers can affect the high producer at any time in the season and can be brought on by a sudden: change m feed, indigestion when she cannot absorb enough feed, bulling when her grazing habits are upset, or even by a spell of bad weather causing her to use . too much of her energy to keep warm. Some cows that go dry for no apparent, reason seem to save themselves from the metabolic diseases by stopping milk production and using the available food to build themselves up again. Farmers seldom realise that 3 times as much feed is required to keep a cow in high production as to feed a dry empty cow and keep her in health. Departmental officers are often told that a certain cow came in, milked outstandingly well if or a few weeks, then just went dry and is being fattened for the works. In most cases she is a well-bred high : producer, and poor winter feeding can be blamed. 1

A few cows that calve in poor condition may build themselves up before they, reach peak production, thus mak“ig a late start; in many cases they go dry earlier. . . Cows which calve in low condition are the majority of what are called temporary sterility or delayed conception cases. Their bodies are not in a fit state for them to hold to the bull and milk at the same time. This trouble is rare in cows which are maintained on a good, balanced ration during pregnancy and lactation. A young heifer which is badly done in her first winter is often under-devel-oped sexually and may not hold until she is 2 years old. Farmers who try to breed fine-boned, small, “typey” cows tend to keep heifers too low in condition, causing a lot of trouble of this nature. ■ • • Uan 9 ers ot Immature heed \ In herds where delayed conception is a serious problem it is very noticeable that when the stock are moved to more mature feed, or when the feed matures in January or February, cows hold without: much . further trouble, Moving cows from lush, young, milkproducing grass to older pastures, or feeding supplementary hay or roughae is _ not a popular cure for falling production, but sustained production is -impossible on unbalanced. rations without paying the price in herd replacements. A common source of trouble is allowing a high producer to build up too much condition during the last month of pregnancy, or wintering her too fat, and then immediately after calving feeding her on young, stimulating, flushing pastures. ’ The stimulus for milk production from the high condition ; and the milk-forcing grass is too much for the cow’s system, as it

causes an excessive milk drain and a heavy, sudden fall in minerals, resuiting in milk fever, grass staggers, or ketosis caused by excessive conversion of fat reserves on a proteinrich pasture which lacks the necessary sugars to burn fats completely. Deaths are frequent in this type of cow from . a combination' of all three conditions, which makes treatment very difficult, If -such cows were fed more hay in early lactation, they would not get an excessive amount of young grass and would have a more balanced food and more time to balance their excess fats from too much winter feed.

The same circumstances operate when a farmer buys a few wellconditioned, in-calf high producers and adds them to an average herd on average feed.- These cows are accustomed to better feed management, and the sudden change thoroughly upsets their fine balance. If they do not slip, they ,go down after calving with milk fever, grass staggers, or ketosis and go dry early. The average cows in the rest of the herd, accustomed to low conditions and not having the same fatal urge to produce, go serenely through the season with few troubles, Further, the high producers left prob-

ably suffer from . delayed conception, and the farmer swears he has been robbed, not realising that the whole sad tale was his own fault. • . Maintenance of Body Weight Each farmer must adjust his feed to suit season, pasture, and herd so that each cow is maintained at about the same body weight throughout the year. That means saving enough roughage and supplementary foods such as hay and roots to prevent a drop in condition before calving and to add bulk and energy to the diet when immature pastures are being grazed in spring. Extra feed will help to smooth out any dangerous sudden changes in the quantity or quality of pastures. At least 15cwt. of hay or its. equivalent should be saved for every cow wintered. Adequate shelter, belts and good covers are invaluable in cold, windy weather. . . After a hard winter, molasses and a few pounds of concentrates in the bail may contribute much toward saving a high producer from milk fever, grass staggers, or ketosis. A cow should not be allowed to build up too much condition immediately before calving, - and she should not be milked right out for a few days after calving to avoid milk fever. A little extra attention during the first heat period, in the form of extra good feed and- molasses, will carry a cow safely over the danger period. Over-exciting or dogging should be avoided. Indigestion, the forerunner of many cases of grass staggers and ketosis, can be avoided by using only good-quality feed. Mouldy hay is dangerous. Well-wintered cows have stronger calves, milk better for longer, and are easier to get in calf ' than those which are less well treated.