DAIRY CATTLE MUST HAVE GOOD FORAGE

L. A. Moore

THE DAIRY COW is built to handle large quantities of roughage. She has a rumen or paunch that holds 2 or 3 bushels of ingested material and acts much like a fermentation vat in digesting the fibrous parts and other constituents of forage crops. She is highly efficient therefore in converting them into products that humans eat.

Harvested forages usually are the cheapest source of nutrients for dairy cattle during the winter feeding season. For the most economical production of milk under average conditions, 75 to 80 percent of the nutrients fed them should come from roughage. In the past much more attention has been paid to the quality and kind of materials going into the concentrate part of the ration than into the roughage part. Yet good forage is more necessary than concentrates to the health and reproduction of dairy cattle. Cattle cannot long survive and reproduce on a poor forage even though the best quality of grain ration may be fed at the same time. The reason is that roughages contain minerals and vitamins that dairy cattle need and that concentrates normally do not supply.

Harvested forages usually are crops stored as hays or silages. Corn and sorghum are commonly made into silage in most dairy areas, although in some sections they may be preserved as fodder. More recently, considerable tonnages of the forage crops have been stored as silages, and farmers in some sections now are keenly interested in methods of barn-drying hays. Needless to say, stage of maturity, conditions of curing, soil, and other such items materially affect the feeding value of any harvested forage. In general, crops harvested at an early stage of maturity and under conditions that prevent loss of leaves have the highest feeding value. Farmers therefore are looking for methods of preserving forages that prevent losses due to bad weather and other conditions and that can produce roughage of high quality.

In this connection the question arises as to the relative feeding values of forages produced by the different methods. Their adaptability to various feeding situations, the supplemental effects of one kind with another, and their uses along with other types of feed are all points to be considered.

Roughages contain vitamins A and D, which (except a small amount of vitamin A in yellow corn) are absent in grain. Every effort should be made to preserve those vitamins in roughage and to produce roughages that contain enough of them.

Forages that are considered high in quality (that is, green and leafy) generally contain the most carotene. The cow converts this substance into vitamin A. Roughages harvested under poor weather conditions or stored improperly may contain too little carotene to keep the cow healthy. If cows are fed poor hay or silage (or even if they are fed good forage in insufficient amounts) they give birth to weak, blind, and dead calves. They also retain the placental membranes.

Do forages that are harvested as grass silage contain enough vitamin D? In experiments at Beltsville, wilted alfalfa silage contained sufficient vitamin D for growing male calves when it was fed at the usual level of roughage feeding. It seems doubtful that there is need for vitamin D supplementation where wilted alfalfa silage is fed, especially where the herd is exposed to a few hours of sunshine each day.

The feeding of good quality forages is also important in maintaining a high vitamin A content of milk and butter in winter. While cows are on winter feeds, the vitamin A content of milk usually drops to 50 percent of the amount present in milk during the pasture season. The vitamin A content of milk in winter cannot be maintained at the summer level even when the best quality of field-cured hay is fed, but grass silage usually is sufficiently high in carotene to maintain the vitamin A content of milk at almost the summer level.

These qualities of roughages are therefore important to cattle and to the consumer of dairy products; they can be retained if the producer takes advantage of every means available to preserve forages. Good quality roughage fed in liberal quantities will supply sufficient vitamins A and D for cattle without need for further supplementation under usual farm conditions and should improve the vitamin quality of the milk produced.

Because of difficulties encountered in field curing, especially the first crop of hay, and the attendant field losses, a considerably greater portion of hay crops has been made into silages during the past few years, particularly in the humid sections of the country. These silages are made by adding molasses or some preservative at the time of ensiling or by wilting the crop slightly and using no preservative. The comparative feeding value of crops harvested as field cured hay or silage has not been studied thoroughly.

In tests at Beltsville by the Bureau of Dairy Industry, wilted alfalfa silage was shown to be as high or higher in feeding value than hay harvested from the same field and field-cured.

Several similar comparisons at Beltsville have shown that the experimental results obtained depend largely on the quality of the field-cured hay fed. If the field-cured hay is of excellent quality, it will be almost equal in feeding value to wilted silage on the dry-matter basis, but if the field-cured hay is of only fair quality the wilted silage will produce more milk.

In a comparative trial at the Virginia Agricultural Experiment Station, clover made into molasses silage produced 10 percent more milk than when the crop was made into hay from the same field. In trials at the Upper Peninsula Experiment Station at Chatham, Mich., in which two groups of cows were used in a double reversal trial, alfalfa from the same field was put up as hay and as molasses silage. The cows fed field-cured hay consumed 30 pounds a day as the sole roughage; cows fed molasses-alfalfa silage consumed 87 pounds a day as the sole roughage. Ground barley was fed as a grain. During the time the cows were on the alfalfa silage they consumed a little less total digestible nutrients a day but out-produced the cows on hay.

These experiments indicate that grass silage (meaning, here, the crops put into a silo regardless of whether they are legumes or grass) is at least equal to hay in feeding value. In cases where the quality of the hay may be low because of poor curing conditions, silage made at the same time and from the same crop may be definitely superior.

During the past 10 years scientists and dairymen have thought and said much about the relative quantities of dry matter that cows will consume in the form of hay or grass silage.

In an experiment at the Dairy Field Experiment Station at Huntley, Mont., the Bureau of Dairy Industry fed grass hay as the sole ration to one group of four Holstein cows. The hay was cut at an immature stage from an irrigated area. A similar crop of grass, put up as silage with slight wilting, was fed to a similar group of three cows. The average dry-matter content of the silage was 33.3 percent. In both cases somewhat more hay or silage was fed than was consumed in order to obtain a proper measure of the cows' appetites. The cows fed the immature cut hay as the sole ration consumed somewhat more dry matter in the form of hay than the cows fed the grass silage made from a comparable crop. The quantities of grass silage eaten each day were large one cow consumed daily 123 pounds of grass silage in her third month of lactation.

At Beltsville, the Bureau of Dairy Industry measured the comparative consumption of dry matter by similar groups of cows fed alfalfa hay or wilted alfalfa silage along with a concentrate ration. They were fed as much alfalfa hay or wilted 'alfalfa silage as they would consume. Grain comprised the rest of the ration. Ten cows that were fed alfalfa silage with a dry-matter content of 55 consumed 23.9 pounds of dry matter as silage and 22.8 pounds of dry matter as hay. Eight cows that got alfalfa silage with a dry-matter content of 62 consumed 25.6 pounds as silage and 24.0 pounds of dry matter as hay.

Although the dry-matter content of the wilted silages fed is somewhat high for silage of this class, as much dry matter was consumed in the form of silage as in the form of hay.

Workers at the Maryland Agricultural Experiment Station conducted two feeding trials involving 10 cows in each of 2 lots. They found that corn silage was more palatable than soybean-millet-molasses silage. The cows refused 1 pound of corn silage a day while they refused 2.56 pounds of soybean-millet silage fed on the same dry-matter basis. The rest of the ration consisted of grain and alfalfa hay.

At the Indiana Agricultural Experiment Station, alfalfa-bromegrass silage was as palatable as corn silage after the cows became accustomed to the grass silage. The rest of the ration consisted of grain and alfalfa hay.

At the New Jersey Agricultural Experiment Station, timothy silages made with molasses and ground barley were found less palatable than corn silage.

Milking cows at the Virginia Agricultural Experiment Station consumed as much dry matter in the form of molasses-clover silage as they did of clover hay made from the same field.

Some difficulty may be experienced in inducing cows to eat grass silage unless they have been accustomed to it as calves. At the West Virginia station it was noted that cows that had never received corn silage refused it at first and had to be starved into eating it for a short period.

Our experiments at Beltsville have shown that cows will eat more of grass silage that has been wilted than of one put up in a more moist condition. The general consensus would suggest that cows will consume enough wilted grass silages to maintain good production.

Dairymen agree that cows on an all-grass silage ration have a craving for some other form of roughage. Likewise cows that get only alfalfa hay or timothy hay as the sole roughage crave some other form of roughage. In practice it would seem wise to feed some hay along with a grass silage as roughage. This fits in well with the harvesting program because the best practice is to put the first crop of forage up as silage and to make the second or third crops into field-cured hay.

The greater emphasis on soil conservation has led to a tendency in some hilly areas to cut the use of row crops and to increase the use of grassland crops, even though corn will usually produce more total digestible nutrients per acre under most conditions. The substitution of hay crops for corn has raised the question of the relative feeding value of grass silage and corn silage.

At the Indiana Agricultural Experiment Station, molasses-alfalfa-bromegrass silage was compared in feeding value with corn silage in two trials in which two groups of five cows each were used in each trial. The silages were fed at the rate of 3 pounds per 100 pounds of body weight. The cows also received a limited quantity of alfalfa hay and a grain mixture. The cows on the alfalfa-brome silage produced slightly more milk but did not gain so much in body weight.