We are receiving questions on two pasture crops--"World Feeder" Bermuda grass and "Legend" lespedeza.  Both crops are promoted favorably with photos and testimonials, but to our knowledge these promotions present no objective university data.

"World Feeder" is well advertised Bermuda grass with an average yield and quality.  Regarding the yield, a Fayetteville, Arkansas study tested it with 14 other cultivars in a 7-yr. study.  It yielded lower than one-third of those tested and did not significantly outyield any of them. Similar data were reported from University tests in surrounding states.  Given the favorable environment in many of these test locations, we can say World Feeder yields no more than any other cultivar.

The quality of World Feeder is similar to other cultivars.  But more important than yield and quality is persistence.  At some locations in Missouri, World Feeder will persist in clipping trials.  We have no objective, University data from grazing trials.  Be assured when there is a stand failure, a low yield, or a low quality test, the poor performance will be attributed to a lack of management.

"Legend" Lespedeza is likely an annual Lespedeza, probably a selection out of Marion (Kobe type).  It may be the seed increase of rogue Korean types that contaminated the seed.  We are checking on this and will know something more over the winter.  We believe it was released by a local seed producer.  We have seen not scientific testing of this crop.

According to the promotional literature, complete with photos and text, it yields more than "Marion" Lespedeza by a 2:1 margin.  At present, we have no data to confirm this claim.  However, we see these claims every year in the absence of University data.  We have learned to take these statements with a grain of salt.   We are not convinced that this 2:1 yield increase will be supported in a replicated, objective trial.

Craig Roberts
Robert Kallenbach

One of the most challenging pasture mixtures to manage in the Midwest is cool-season grasses along with native warm-season tall grasses. The growth habits are very different, the relative palatability at certain times of the year are quite different, the required residual heights and rest periods are different, and, obviously, the seasons of growth are different. While the experience with continuous grazing or slow rotations is that these species are unlikely to occur in the same pasture, many producers have seen the tall grass component of their pastures increase with management-intensive grazing (MiG). A remnant population of native grasses actually exists in most long-term cool season pastures in the corn-belt region. If land has been extensively cropped in the past, native grasses is unlikely to develop without interseeding. From time to time, I am asked for a management guide for encouraging native tall-grass increase in cool-season dominant pastures without the use of tillage or chemicals. The following is a guide through the grazing season for encouraging warm-season grass development in existing cool-season pastures where a remnant population is observed.

All of these recommendations are based on the assumption that there are multiple paddocks in the grazing unit and length of grazing period and rest period can be varied as needed. The target paddocks should be some of the first paddocks grazed in the spring. Initial greenup is going to be composed entirely of cool season species. This early growth needs to be grazed fairly severely, leaving as little as two inch residual growth. In northern Missouri, this grazing usually takes place late-March to mid-April. Warm-season grass growth usually begins in late April or early May. A second grazing will need to be made as the native grass is just getting started. This second grazing is not as severe as the first, leaving 3 to 4 inch residual. Timing is early to mid-May followed by rest until mid to late June.

The two early grazings have slowed down cool-season growth and the mid-May to mid-June rest period has allowed the warm-season grass to reach target grazing height of 10 to 12 inches. The first grazing of the warm-season grass should leave at least 6 inch residual and be followed by at least 30 days of rest. The second warm-season grass grazing should occur late July to early August. Until the warm-season component has reached the desired level in the mixture, avoid grazing later than August 15. Regrowth should reach at least 10 to 12 inches before frost. A final grazing can be made after frost, but plan on leaving at least 6 to 8 inches of native grass stubble. This usually is not a problem as the cattle will prefer to graze the green cool-season material out of the mixture.

Not grazing the final growth and conducting a spring burn may accelerate the rate of warm-season grass increase in the sward. Three to five years of this management strategy will usually result in a significant native grass component in the mixture. The stronger the remnant population at the beginning, the greater the final native grass component will be. Combining severe winter grazing with spring no-till seeding of native grass can also help accelerate the process. With experience, most grazers learn how and when to adjust grazing practices to shift the mixture in whatever direction they choose. Repeatedly grazing every paddock to very short residuals will almost always keep the mixture predominantly cool-season species.

Jim Gerrish, Editor
GerrishJ@missouri.edu

Introduction: Both forage availability and forage quality may limit animal performance in grazing situations. In many research trials, only one of these parameters may be measured. Failing to take both into account often leads to over-prediction of expected animal performance or erroneous conclusions about what factor is limiting animal performance. In other cases both are measured but are not combined to provide a meaningful relationship to animal requirements and performance. Knowing both forage production and nutritive value of the forage allows the grazing manager to determine the nutrient supply and demand balance.

Net energy demand of most classes of livestock under given production and environmental scenarios has been determined. Net energy content of forage can be calculated from forage analysis and forage availability or accumulation rate can be measured. With this information, supply and demand relationships can be determined and appropriate stock policy and stocking rate decisions can be made. Our objective was to compare yearling steer net energy demand per acre with forage net energy available per acre and determine what factors most likely limit gain of grazing yearlings.

Materials and Methods: This project determined net energy availability for cool-season grass-legume pastures rotationally stocked at four stocking rates. Energy demand of yearling steers grazing these pastures was determined based on net energy requirements for maintenance and growth.

Pastures consisted of endophyte-free tall fescue (Festuca arundinacea Schreb.), orchardgrass (Dactylis glomerata L.), and Kentucky bluegrass (Poa pratensis L.) overseeded with red clover (Trifolium pratense L.) and birdsfoot trefoil (Lotus corniculatus L.) at the beginning of the study in 1995. Within each block, pastures were randomly assigned a stocking rate and then spilt to either continuous or rotational stocking treatments. The rotational grazing cells consist of 12 equal sized paddocks. Target stocking rates were 300, 600, 900, or 1200 lb liveweight per acre at turn-out as yearling steers weighing approximately 575 lb/head. Sixteen 10 acre pastures were used in the study to provide two replications of each treatment in a randomized complete block design with split plot assignment of treatments.

The study was conducted from 1996 through 1999 with grazing beginning in early to mid-April and ending around September 10. First grazing cycle consisted of daily rotation through the 12 paddocks and subsequent cycles usually consisted of 2-day grazing periods with 22 day rest periods. All stocking rates were managed on the same rotation frequency.

In each rotationally grazed pasture, four paddocks were sampled in each grazing cycle to determine forage availability. Nine 3.2 ft² quadrats were clipped both pre- and post-grazing in each paddocks. Bulk wet weight was measured and a 150 g (+/-) subsample was oven dried to determine forage dry matter. Oven dried samples were retained from each clipping for forage analysis. All forage samples were analyzed by NIRS to determine crude protein, ADF, and NDF levels. Each year approximately 100 samples were analyzed through standard wet chemistry procedures to determine the same parameters and calibrate the NIRS data. Net energy for maintenance (NEm) was calculated from ADF value using the relationship:

Forage NEm = 1.04-(0.0104 X ADF)
Availability of NEm per acre was calculated as:
Forage NEm/acre = Herbage mass (lb/acre) X NEm (Mcal/lb)
Net energy demand for yearling steers was determined by the following equations:
    NEm=.077 X ((liveweight/2.205)^.75
    NEg=.0493 X ((liveweight/2.205)^.75) X ((ADG/2.205)^1.097)
Animal demand per acre was calculated as:
Required NE/acre = NE/head X Head/acre

Results and Discussion: Forage availability was significantly affected by stocking rate with date of peak forage availability also being determined by stocking rate (Figure 1). Increased animal demand of higher stocking rates resulted in lower mean forage availability throughout the season. While peak forage availability occurred on July 29 for 300 pound/acre stocking rate, the same event occurred on June 8 for 1200 pound/acre stocking rate. By the end of the grazing season, forage availability on 1200SR was approximately 35% of 300SR. The figures shown are forage availability at the beginning of each grazing period. Both mean and residual forage availability were below the levels shown.

At some level of forage availability, forage intake is limited by the physical inability of the grazing animal to consume any more forage. From the standpoint of grazing mechanics, intake is determined by time spent grazing, biting rate, and bite size. Low forage availability limits bite size to the extent that the animal cannot spend enough time grazing or take enough extra bites per minute to compensate. A commonly cited figure for the lower threshold for intake restriction of 1800 pounds/acre. Forage availability at initiation of grazing in 1200 SR was below this level from late July until grazing ended in September. Residual forage availability was well below 1800 pounds for most of the season. Residual availability did not fall below 1800 pounds all season for only 300 SR.

The NE content of forage samples was very good throughout the season with mean levels remaining above .65 Mcal/pound for all treatments (Figure 2). This data represents whole plant samples so animal selection would be expected to result in even higher level of dietary energy intake. The idea that cool season grasses are low quality during the summer months is not born out by this data. In general, cool season grasses are low quality only if they are allowed to become so. The highest stocking rate produced the highest NE forage while lowest stocking rate produced the lowest NE forage. Crude protein content , while not reported in this paper, responded to stocking rate similarly.

These two pieces of data suggest that animal performance was more limited by declining forage availability as compared to forage quality. The observed NE levels in the forage should be adequate to produce average daily gain in excess of 1.75 pounds/day if intake were not limited. However, by mid-July all treatments were gaining less than 1.0 pound/day. It may be that reduction in ADG at this time was due more to environmental stress than forage conditions. Nighttime low temperatures were frequently above 80^oF with humidity in excess of 70%. These conditions are not conducive to steers achieving high pasture intake.

Net energy available per acre was greatest throughout the season for the lowest stocking rate and least for the highest stocking rate (Figure 3). Available net energy declined rapidly after mid-June for 1200SR. During a typical two-day grazing period, NE consumption by the steers would exceed 50% of the available NE. Forage utilization in excess of 50% will usually result in depressed animal intake unless forage is of exceptional quality.

Daily net energy demand declined through the season for all treatments with more rapid decline occurring as stocking rate increased (Figure 4). The decline was due to decreased rate of gain as the season progressed. It is very difficult to say whether gain decreased due to lack of energy intake or other environmental factors. For all but the highest stocking rate, both forage availability and net energy content were at levels which would not normally be expected to restrict voluntary intake.