GRASS FOR THE PRODUCTION OF BEEF

W. H. Black, D. A. Savage

BEEF CATTLE lead all classes of American livestock in the consumption of grass and grassland crops. They utilize about one-third of the permanent Pastures, three-fourths of the range areas, and a high percentage of the harvested crops. Grass usually represents the principal and cheapest feed of beef cattle. Pastures can be regarded as a costly source of feed only on highly productive farm land, but their use in rotation with cultivated crops on such land is certain to continue and be expanded as a sound practice.

About 12 billion pounds of dressed beef and veal was produced in the United States in 1947 through the conversion of grassland crops into meat by cattle. The quantity of forage required to produce this huge output of meat is indicated by the average daily requirement of beef cattle. An average beef animal consumes at least 50 pounds of green or succulent forage daily in humid locations and probably about half that quantity in drier areas.

Our experiments near Jeanerette, La., in 1939, 1940, and 1941 in which pastures were grazed to maintain the weight of steers indicated a carrying capacity of more than 1,800 pounds of animal weight an acre. The seasonal yield from clippings was 27,403 pounds of fresh forage an acre. That was 43 percent greater than the consumption by comparable steers that were kept in a dry lot and fed fresh clippings from a similar pasture so as to maintain their weight at the same level. The dry-lot steers ate about 50 pounds of fresh forage daily per 1,000 pounds of live weight. This quantity of vegetation contained 13.02 pounds of dry matter and provided 1.17 pounds of digestible protein and 8.77 pounds of digestible nutrients. These values are within the range of theoretical requirements for the maintenance of 1,000-pound mature beef animals, plus 25 percent for the "activity" factor.

A study of grazing capacity, conducted by S. E. Clarke and associates, of the Canadian Department of Agriculture, has indicated that about 25 pounds of the native grass of southern Alberta, Saskatchewan, and Manitoba is required to make a pound of beef and leave sufficient growth as carryover. The grasses of southern Canada are more nutritious and contain less moisture than the more succulent grasses of humid areas. The native grasses in the Great Plains of the United States are likewise superior in year-long nutritive qualities to those of humid areas, according to results of analytical and grazing work reported by D. A. Savage and V. G. Heller.

Grasses furnish almost the entire feed supply of beef cattle for at least half the year in most areas and for the entire year in some.

In the Great Plains and other parts of the West, breeding herds are maintained on grass and fed only a limited quantity of protein-rich supplements during periods of drought or snow. The native bluestem grasses of the Flint Hills of Kansas and of the Osage region of Oklahoma are noted for their fattening qualities. Thousands of fat cattle from those areas are slaughtered annually.

The Mineral Point section of southwestern Wisconsin and the Appalachian region enjoyed a similar reputation for many years. In recent times, however, the trend there has been toward the production of farm crops. The fattening of steers on grass alone is giving way to the production of beef on grass and harvested crops supplemented with concentrates. The fattening of aged steers is being replaced by breeding herds, the creep-feeding of calves, and the fattening of yearlings and 2-year-olds on grass and concentrated supplements.

Blue grama is the most valuable and widely distributed native grass in the Great Plains. It occurs from the Peace River of Canada to Mexico and represents about a 50-50 mixture with buffalograss from southeastern Montana southward through the Plains. These two famous short grasses, with their comparatively high feed value at all stages of growth, give to the Great Plains region its enviable reputation as the home of feeder cattle the Nation's leading area for the yearlong grazing of beef cattle.

Many other desirable native grasses add greatly to the value of the region for grazing purposes. Chief among these in the Northern Great Plains is western wheatgrass. This cool-weather grass helpfully lengthens the green grazing season in the short-grass region and often produces more total feed than the true short grasses. It is well established from the Dakotas to the Pacific Northwest and from northern Alberta to central Colorado and Kansas, with some occurrence in Texas and Oklahoma. It is found in nearly all upland pastures of the Northern Great Plains, but is most abundant on lowlands and on heavy upland soils. Flats subject to flooding are frequently occupied by western wheatgrass to the almost total exclusion of other grasses; they have furnished excellent hay and winter pasture for beef cattle since the country was first settled.

Western wheatgrass provides highly palatable grazing in the spring and fall in the Northern Great Plains and throughout most of the fall, winter, and spring months when reseeded in parts of the Southern Great Plains. The grass is not so palatable as the short grasses in the cured stage of growth but is eaten readily when other grasses are not available. It does not recover rapidly from close early grazing but, when allowed to complete its growth, it ranks among the leading forage-yielding grasses of the region.

Carrying Capacity

Moderation in stocking native range has shown outstanding advantages in all degree-of -grazing tests conducted throughout the West. In most instances total gains per acre have favored the heavier rates of stocking, but the fallacy of heavy grazing has been consistently demonstrated in greatly reduced gains per head, lowered market value of the cattle produced, and decreased vigor of the vegetation.

About 7 acres of native range represented the proper carrying capacity for a 2-year-old steer for a 5-month grazing season at Mandan, N. Dak., according to experiments conducted by J. T. Sarvis between 1916 and 1935.

This rate was the only, degree of continuous grazing that produced the highest gain per acre without sacrificing gain per head, length of grazing season, or vigor of vegetation. It was Shown that 20 to 25 percent of the annual forage production must be left Standing at the close of the season in order to protect the range from vegetative injury. The 7-acre rate returned 12.9 pounds more steer gain per acre than the 10-acre rate, produced almost the same gain per head, and maintained the vigor and desirable composition of the vegetation. Heavier rates of stocking-3 and 5 acres per head returned more gain per acre for the 20-year period, but produced much less gain per head and badly damaged the desirable vegetation.

Similar results were recorded by George A. Rogler for the yearling steers grazed on the same pastures at four rates of stocking during the next 8-year period, 1936-43. He also found that yearlings consume about 30 percent less forage than 2-year-olds.

The Department's experiments at Ardmore, S. Dak., from 1919 to 1930 showed that the native vegetation, consisting mostly of western wheatgrass, blue grama, and buffalograss, is not damaged by cattle if grazing is delayed until the middle of May and the pasture is stocked so that the cattle make fair gains during the growing season. Some loss in fall weight of cattle did not reflect injury to the range nor loss in carrying capacity. The more intensively grazed pastures produced greater seasonal gain per acre than those less intensively used. None of the rates abused the vegetation, and 10 acres per head was considered the optimum carrying capacity of the range.

Cooperative grazing experiments conducted with a breeding herd on native range at Miles City, Mont., showed that heavy, moderate, and light rates of stocking-23.1, 30.5, and 38.8 acres per head were negligible in their effect on the vegetation but pronounced in their influence on the production of beef cattle. Conservative grazing, as represented by the average for moderate and light rates of stocking, showed increases of 6 percent in percentage of calf crop, 28 pounds in weaning weight per calf, 45 pounds in weight of calf per cow, and 98 pounds in weight of cow, when compared with the heavy-grazing rate.

In contrast with the results recorded at Miles City, three degrees of continuous yearlong grazing and two degrees of continuous summer grazing of native range near Woodward, Okla., (where the Southern Great Plains Field Station is located) , were much more evident in their effect on the vegetation than on cattle gains during the 5-year period 1941-46. In yearlong grazing rates of 6.6, 9.8, and 12.9 acres per yearling steer, the heavier rate produced average annual gains of 25 pounds per head less and 22 pounds per acre more than the average of the two more conservative rates of stocking. The detrimental effect of overgrazing on the vegetation was increasingly evident throughout the 5 years, but the experiment had to be continued into the sixth year before heavy grazing caused sufficient reduction in gain per head to result in less gain per acre than was obtained from the moderate rate. More total gain was produced with fewer cattle during the winter of 1946-47.

Other sets of pastures were grazed only from April to October on both a continuous and rotational basis at the overgrazed rate of 4.1 acres per yearling and the moderate rate of 6.0 acres per head. In these comparisons, the heavier rate reduced average gain per head to the extent of 35 pounds and seriously damaged the vegetation but caused a 15-pound increase in gain per acre. These results also showed that the optimum carrying capacity of non-mowed native range in the vicinity of Woodward was 10 acres per steer on a yearlong basis and 6 acres for the growing season.

Deferred-and-rotation grazing has shown no advantage over continuous grazing of sufficient magnitude to justify the extra expense involved in fencing and water development in the Great Plains. This rotation system consists of moving the cattle from one part of a pasture to another at intervals during the growing season of the vegetation. Its original purpose was to enable seeds produced by deferment one year to become established before grazing occurred the next year. However, natural reseeding of range plants rarely occurs extensively in the dense perennial grass cover of the Great Plains. Therefore, in order to be superior to continuous grazing, this rotation system must increase the vigor of the deferred plants by a greater margin than is required to offset their heavier use when grazed.

In the long-time grazing studies conducted near Mandan, N. Dak., continuous grazing at the moderate rate of 7 acres per head resulted in significantly higher gains than were obtained from deferred-and-rotation grazing at heavier rates. The results, as reported by Sarvis in 1941 and Rogler in 1944, showed conclusively that the deferred-and-rotation system of grazing was detrimental to yearling gains and had no advantage for 2-year-olds unless it was compared with continuous grazing at abusively heavy rates of stocking.