The Concept of Complementary Forage Systems

No single forage can supply the nutritional requirements of grazing beef cattle for more than a few months during the year. The quantity and quality of any given forage continuously changes as the plants go through their normal life cycles. By combining different types of forages together in a forage system, we can increase the amount of time during the year when forage quality and quantity will be high enough to support efficient beef gains. This is the concept of a complementary forage system in which we use the strengths of several forage types while minimizing their weaknesses. Using a mixture of forages should also decrease annual fluctuations in forage production. This diversification helps reduce production risk.

This paper contains an example of a complementary forage system in the southern plains and describes some general principles for developing complementary forage systems. Selections of forages that can be used in a complementary forage system in this region are suggested. In this approach, we assume that native rangeland is the foundation of our complementary forage system. To this foundation, we will add one or more introduced forages to build a forage system that increases livestock production while decreasing costs of forage production. Also, the focus of these forage systems is to provide as much nutritious and palatable forage directly to the grazing calf as possible to reduce the essential, but inefficient, transfer of nutrients through the cow to the calf.

An Example of a Complementary Forage System

Complementary forage systems for cow-calf production have been evaluated at Woodward, Oklahoma, for several years. A spring-calving cowherd grazing on native rangeland (NR) year round was compared to a fall-calving cowherd grazing a mixture of rangeland and complementary farmed forages (NRCF). The rangeland system was stocked at 20 acres per cow. The NRCF system was stocked at 13.6 total acres per cow, 12.1 acres of rangeland and 1.5 acres of cropland. About one-half of the cropland acres were used to produce winter wheat and the other half was double-cropped to winter wheat and summer-grown pearl millet or sudangrass. Wheat was seeded in early September and grazed out by late May each year. The summer forage was seeded as soon after wheat graze-out in late May or early June as precipitation allowed. Nitrogen fertilizer was applied at a rate of 50 lb. N per acre before wheat seeding and again in February. The summer forage was not fertilized and relied on the residual nitrogen.

In the NR system, calves were born in February and March and weaned in mid September. Calving occurred in September and October and calves were weaned in mid August in the NRCF system. Cows and calves in the NR system grazed rangeland year round. Calves in the NRCF system had unlimited access to the farmed forages through creep gates from birth to weaning. If fall precipitation was adequate, cows in the NRCF system grazed wheat during the breeding season (Dec 10 to Feb 18). They also grazed wheat from March through May. These cows were also allowed to graze farmed forages whenever the forage supply was greater than the calves could consume.

The percentage of calves weaned per cow exposed and the calving interval was not different between the NR and NRCF forage systems over 7 calf crops (Table 1). Calf weaning weights were 192 lb. heavier in the NRCF system. Calves in the NR system actually gained weight more rapidly but the calves in the NRCF system were about 120 days older at weaning. Beef production per acre increased 87% with the NRCF system while land area per cow was reduced 32%.

We conducted an economic analysis of the two production systems assuming a 2000-acre land base. We used current prices for livestock and production inputs. Land costs were calculated using cash rental rates. Herd sizes were 100 cows for the NR system and 147 cows for the NRCF system.

Although the total number of acres allowed per cow was less in the NRCF system, land costs per cow were similar between the two systems (Table 2). This is because the NRCF system included cropland, which has a substantially higher rental rate than rangeland.

The cost of forage production was substantially higher for the NRCF system. This was due to the farming costs for the cropland that totaled $60 per acre. Forage production costs for the NR system were due to herbicide application for weed and brush control on a three-year cycle. Purchased feed costs were similar for the two systems. Less protein supplement was fed to the fall-calving NRCF cows. This was offset by supplemental grain fed to the NRCF cows but not to the spring-calving NR cows.

Total variable costs were higher for the NRCF cows, mainly due to the cost of forage production. Fixed costs were lower for the NRCF cows because costs were spread over more animals. Fixed costs may seem low in this example because land costs were calculated as cash rent and included in variable costs. Total costs were about $50 higher per cow in the NRCF system.

Input costs were higher for the NRCF system but income was also higher because of the large increase in calf weaning weight (Table 3). Income per cow was almost $100 higher for NRCF cows. As a result, net returns for the NRCF system increased by $45 per cow. Net returns per acre increased 105% for the NRCF system. The cost of beef production was about 5 cents per lb. higher for the NR system.

Developing a Forage System

Any forage system must be designed for each specific farm or ranch. Every operation has a unique set of resources, production constraints, and management objectives and skills. What fits well for one producer may not apply to other producers. However, a few guiding principles will help managers to develop forage systems for their operations.

The first principle is that grazing is more cost-efficient than machinery as a method of harvesting forage. We cannot totally eliminate the use of harvested forage in a yearlong beef production system, especially where snowfall is a significant factor. Forage costs, however, will almost always be lower when the cattle harvest the forage rather than relying on high-cost machinery. This is why many dairies in the northeastern U.S. are now moving to intensive grazing systems and away from harvested forages. Recent studies in the Nebraska Sandhills confirm that forage systems with the largest amounts of grazed forages are most profitable.

A second principle is to maintain the proper balance of rangeland and introduced forages. A ratio of 10-25% of the land area producing introduced forages and 75-90% in rangeland has worked well in our region. Too little introduced forage eliminates many of the benefits of complementary forage systems. Too much introduced forage increases management headaches, the use of machinery, and annual fluctuations in forage production. Forage in excess of needs at a given time upsets the balance between production and consumption, which then requires machine harvesting.

The introduced forages generally have a more rigid production and utilization schedule than rangeland. Timing of the use of the native plants is less critical. Cattle graze on native vegetation until the introduced forages are ready for grazing. The cattle then graze the introduced forages to their capacity and move back to rangeland until the introduced forages are again ready to be grazed. In this way, the rangeland area provides flexibility in the forage system. As the proportion of rangeland decreases, the overall flexibility in the system also decreases.

Third, we usually think of using introduced forages to increase the quality of the forage supply. However, introduced forages also greatly increase the quantity of forage produced. Individual animal performance (weaning weight, % calf crop) is often not increased with a complementary forage system. The improvement in total beef production comes from increasing the stocking rate (allowing less land per head) or from allowing a major change in the management system (fall versus spring calving). In either case, these changes depend on increases in both forage quantity and quality.

Finally, perennial complementary forages have several advantages over annual forages. Perennials do not have to be re-established every year, reducing input costs and risks. Perennials provide more stable forage production from year to year. Fluctuations from high to low years are smaller with perennial plants. Annuals may produce more forage in good growing seasons but often produce substantially less forage in unfavorable years. For these reasons, perennials generally provide better yearlong soil protection than annual plants. If factors such as forage production or quality are similar, we should chose perennial forages over annual forages.

Differences in Management of Introduced Forages and Rangeland

Management of introduced forages and rangeland are fundamentally different. These differences should be kept in mind if we are to make optimum use of both forage types. Introduced forages often grow more rapidly over a shorter period of time than native vegetation. This means that forage quality often declines rapidly for introduced forages once growth has peaked. Native vegetation grows more slowly over longer time periods and tends to maintain forage quality. Diet quality of cattle grazing on native vegetation is also maintained because the animals have a greater variety of plant species to select. Introduced forages are often best used intensively when they are at their highest quality while rangeland should be used to fill the gaps between the high production periods of introduced forages.

The production response to fertilizer or herbicides will be larger for introduced forages than for native vegetation. Introduced forages have been selected by agronomists for their ability to efficiently utilize fertilizer and to vigorously compete with other vegetation or to respond rapidly to weed control. Native plants have been selected over centuries to survive in the natural environment without additional inputs. They are adapted for survival, not production. Managers will increase efficiency by intensifying management on the introduced forages and applying ecological principles to the grazing management of the native vegetation. The rest periods received by the native vegetation while cattle graze introduced forages are a significant advantage of complementary forage systems.

Introduced forages can generally withstand higher grazing pressure than native vegetation. As with added inputs, the introduced forages have been selected, in part, for their ability to withstand heavy use. While many native grasses are resistant to grazing, they will not maintain forage production at the level of introduced forages when utilization is excessive. On the other hand, any forage can be overgrazed. We should not use introduced forages as an excuse to graze excessively.

Introduced forages are best grown on the better soils. Steep, rocky, or shallow sites make establishment of introduced forages difficult and also limit their potential forage production. Expensive inputs, which include establishment costs, should be limited to the better sites to improve economic returns. Sites with less potential should be left in native vegetation. When comparing the productivity of introduced and native forages, we should also remember that the introduced forages are generally growing on better soils.

Finally, we try to maintain stands of introduced species in as pure a state as is practical. This is called a monoculture, meaning "one species." Natural monocultures are very rare because other plants continually try to establish in areas dominated by a single species. We attempt to control these invasions in introduced forages with herbicides, grazing management, and possibly fertilizer. On the other hand, the complexity of native vegetation as a mixture of many different species provides resiliency and stability to the integrated forage system. The variety of native species helps maintain diet quality through the different grazing seasons. This mixture smoothes forage production as precipitation varies seasonally and annually.

Management of Farmed Forages

To manage farmed forages in the drought-prone southern plains, moisture conservation is a primary concern, especially with double-cropping systems. Each crop should be completely grazed-out to minimize the use of soil moisture as the crop matures. Tillage operations must be timely so that each crop is established quickly and forage production occurs as rapidly as possible. While still important, weed control is not as critical in grazing programs as it is in producing a grain crop. As long as the weeds are not noxious, some may produce usable forage and can be grazed along with the forage crop. This saves farming costs compared to those needed to produce grain.

Introduced Forages

It is beyond the scope of this paper to discuss all of the possible introduced forages in great detail. There are many options in the selection of components to blend with rangeland in a complementary forage system. Consideration should be given to the gaps (both quality and quantity) in the current forage production system and the level of management inputs needed for a particular forage. Several introduced forages and some important management characteristics are listed in Table 4.

Summary

The example discussed here was a cow-calf operation but these forage systems have also been evaluated for yearling production systems with similar results (see below). Additional inputs for forage production are required for complementary forage systems but beef production should also increase. However, increases in beef production do not automatically mean improved profitability. The additional inputs must be efficiently converted into beef. Further research and practical development is needed to devise "all perennial" complementary forage systems. Such systems will retain the advantages of production resiliency, improved nutrition of grazing animals, and increased stocking rates while markedly reducing farming costs and enhancing soil conservation.

Complementary Forage Systems for Stockers

A series of studies were conducted using yearling steers to develop more efficient stocker production systems.

Native Range System (NR).

The stocking rate for the continuous yearlong native range treatment was considered to be at a moderate intensity of 8.8 acres per steer (Table 5). Yearling operations yielded 50% more beef gain per acre (44 lb) than a cow-calf operation (25 lb).

These early studies indicated that continuous grazing was generally a more efficient system of producing beef than was 2 or 3 pasture, monthly or bimonthly rotation systems. Apparently, native range stocked yearlong suffered less vegetation damage in drought years and improved more during wet years than did those stocked summer long. In all of these studies, proper distribution of grazing was frequently a more serious problem than obtaining the proper stocking rate or selecting the appropriate grazing system.

Native Range – Improved Perennial Grass System (NR-IPG).

This system utilized improved perennial forages to augment the production of native range. Initial studies were with weeping lovegrass followed by trials with Old World bluestems giving similar results. The average yearlong stocking rate was 4.5 acres of native range plus 0.5 acres of a improved perennial grass (Table 5). Typically, the cattle grazed native range from late October through November and then switched to dormant lovegrass or Old World bluestem from December until early spring (March or April). Cattle grazed native range from the early spring until about May 10, when the improved perennial warm-season grass was ready to graze. Lovegrass or Old World bluestem was grazed from about mid-May through August. Cattle were removed from improved grass in late August to allow it to rest and make root growth prior to the end of the growing season. From about September 1 the cattle grazed native range until sold in early October. The NR-IPG system generally increased carrying capacity 82% and beef production per ha 73% over the NR system. Winter gains were very similar for both the NR and the NR-IPG systems. Individual gains, however, were about 10% better for yearling steers on NR system than those grazing the NR-IPG system. The NR-IPG system, however, required only 5 acres per steer compared to almost 8.8 acres on the NR system. There was a significant increase in gain per acre from 44 lb on the NR system to 72 lb on the NR-IPG complementary system.

Native Range – Wheat / Sudan System (NR-W/S).

About 4.5 acres were allowed for each yearling animal in the NR-W/S system (Table 5). Of this 3.5 acres was native range and 1.0 acres was used for double cropping winter wheat or rye and a summer crop of sudan, pearl millet or forage sorghum. Generally, the steers grazed native range from late October to March 15. In some years, although generally rare, there was sufficient soil moisture to produce grazable winter wheat or rye forage in the fall and early winter. During these years, the cattle were allowed to graze the winter annual forage. In most years, the winter annual was grazed from early March to June 1. The cattle were moved to the native range in late May or early June. The yearling stockers remained on native range through midsummer or until the sudan or pearl millet, planted as a double-crop on the same land as the grazed-out winter annual, generally mid to late July. The cattle remained on the summer forage until sold in early October.

The farmed forages were fertilized with nitrogen and phosphorus (30-50 lb/ac) about October 1, prior to planting the winter annual. About 60 lb/ac of either wheat or rye was planted in September or early October. The winter annual was top dressed with an additional 30 lb of nitrogen on about February 15. Once the winter annual was grazed out, the land was prepared for planting of the summer crop when soil moisture was adequate, generally in mid June. No additional fertilizer was applied for the summer crop.

The NR-W/S system increased carrying capacity almost 90% and beef production was essentially doubled over the NR system. Gain per steer on this complementary system was 30 lb more yearlong than on the NR system. Up until August 1 very little difference in steer gains occurred between the two systems. Generally, forage quality declined in late summer and animal gains tend to decrease on the NR system. Steer grazing the sudan forage gained 31 lb more per head than those on the native range. This additional gain was sufficient to offset the farming cost on the NR-W/S system. Grazing annual forages in May and from August 1 until sold in October rested the native range during critical periods of plant development. The native range increased in vigor sufficiently to withstand the heavy grazing that occurred in June and July and during the winter period when only 3.5 acres was allowed per steer.

Improved Perennial Grass – Wheat / Sudan System (IPG-W/S).

One-half of the land used in this system was in weeping lovegrass and the remaining half was planted to double crop wheat/sudan as described in the NR-W/S system (Table 5). Other improved perennial grasses could be substituted for lovegrass. The average yearlong stocking rate per steer was 1.0 acres of lovegrass plus 1.0 acres of wheat/sudan. Again, the animals grazed improved grass from late October until March 15. From mid March to early June the cattle were on graze-out winter wheat or rye. The grass was grazed throughout the summer when it was at its optimum forage quality and growth. From early August until the selling date in October the cattle grazed the summer forage. When there was more improved grass than needed for grazing, hay was made and stored for use during forage deficient times.

The IPG-W/S system increased carrying capacity and beef gains per acre markedly compared to the native range system. Gain per steer on the complementary system were 15 lb greater in the winter, 33 lb less in the summer and 20 lb less overall than steers on the NR system. This complementary system, however, produced four-fold more beef per acre than the NR system since only 2.0 acres of land were required per yearling animal compared to 8.8 acres per steer on the NR system. Additional management, labor and machinery were required.

Wheat / Sudan System (W/S).

The W/S system was the most intensive forage beef production system evaluated in this series of investigations. In this case, the animals were stocked at 1.0 acre of land that was used for double cropping of winter wheat or rye and a summer forage such as sudan, pearl millet, or hybrid forage sorghums. The annual pastures were subdivided into 6 divisions and the animals rotated through these divisions on an as needed basis. Whenever forage was in excess of what was needed for the current grazing, hay was made of either the wheat or the summer forage and stockpiled for feeding under drylot conditions when the animals were not on pasture or when they were grazing low quality aftermath and needed supplemental forages.