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Superintendent
David Davis
21262 Genoa Road
Linneus, MO 64653
Phone: 660 895-5121
FAX: 660 895=5122
Email: DavisDK@missouri.edu

Forage Systems Update
Vol 11, No. 2

Research approach: Pastures for stockpile grazing were clipped to 3 to 4 inch residual on Aug. 15 following spring and summer rotational grazing and N fertilizer was applied as ammonium nitrate at 80 lb N/acre on Aug. 17. Winter annual pasture were established into chemically killed tall fescue sod. Endophyte infected tall fescue pastures were sprayed with 2 quarts Roundup-Ultra/acre on July 31. On August 17, a mixture of 'Marshall' annual ryegrass and cereal rye was no-till drilled at 15 and 50 lb/acre, respectively. Nitrogen fertilizer was applied at 80 lb N/acre as ammonium nitrate on Aug. 17. Pastures were allowed to grow unused until November 14. Three replicate sets of pastures of ten acres each were used for each forage treatment.

Cattle were initially allowed a new strip of forage every three days with allocation based on measured forage availability and a target temporal utilization rate. Approximately halfway through the study, pasture allocation was made with the objective of maintaining an acceptable BCS on the cows. Each forage strip was sampled to determine forage availability and quality prior to grazing. Within each strip, three .25m2 quadrats were clipped to ˝ inch residual. Mean sward height was measured at each quadrat prior to clipping. In addition, 50 rising plate readings were taken in each strip. Residual forage height was measured after grazing and 50 rising plate measurements taken. Quantity of residual forage was determined by clipping quadrats on three strips in each pasture to calibrate the predictive equations for measured height and rising plate meter. Residual forage for each strip was calculated based on the height:yield relationship. Pasture utilization rate was determined as the disappearance of forage from the pre-grazing to post-grazing forage availability measurement.

Angus X Gelbvieh cross cows with calves sired by the opposite breed of the dam's sire were used in this study. Both mature cows and first calf heifers were used with calving occurring between Sep. 6 and Oct. 18. Cows were stratified based on age and date of calving and were assigned randomly within strata to either stockpile or winter annual pasture treatments and rep within treatment. Each treatment group consisted of six cow-calf pairs, four multi-parous cows and two first calf heifers. Cows and calves were weighed unshrunk on two consecutive days (Nov. 13 & 14) at the beginning of the study and sorted to their respective treatments on the second weigh day. Cow body condition score (BCS) was also recorded. Cows and calves were weighed every 28 days subsequently and BCS recorded. Cows and calves were removed from the winter annual pastures on February 15 following weighing events on February 14 and 15. Cows and calves were removed from the stockpile pastures on March 19. Bulls were present in each pasture from Dec. 5 until Jan. 22.

Figure 1. Precipitation for the study period was about 20% below normal resulting in somewhat lower than expected pasture yield.

The study design called for another replicated treatment of hay fed cows and calves. Because not enough cows had calved by the beginning date for grazing, the hay treatment from this year is not a statistically valid comparison, but meaningful differences in feed costs and calf ADG from birth can still be brought out. Calves in the hay fed group were 36 days younger than calves on pasture treatments. Per acre costs for pasture establishment and management reported are based on actual costs incurred in this study. Labor and fencing requirements are prorated based on the land area and time required for the movement and management of a 100-cow herd. Daily feed costs are based on actual number of grazing days per acre for the pasture treatments and production cost and consumption rate in the hay comparison.

Results and Discussion: The winter 2001-2 will be remembered as being very mild. Unofficially, it has been reported as the fourth warmest winter in Missouri since records have been kept. This factor must be considered when reviewing the results of this study. Only two major winter precipitation events were experienced during the course of the study. In early February, about four inches of mixed ice and snow were receive and remained on the ground approximately ten days. Over a two-day period while conditions were most unpleasant, 30 pounds of hay were fed per cow-calf pair on winter annual and stockpile pastures. In early march we received about four inches of snow with 40 to 60 mph winds and wind chill near -30EF and 15 pounds of hay was fed per cow-calf pair on stockpile pastures as the cows had already been moved from winter annual pastures. Other than those two brief periods, the winter was very open and dry, ideal for year-around grazing.

Photo 1 . Fall calving cows and calves grazing stockpiled tall fescue on Jan 28, 2002.	Photo 2. Fall cows and calves grazing through 4" of ice and snow on February 4, 2002.

Pasture performance:Dry conditions in the fall reduced potential growth on both the winter annual and stockpile pastures (Figure 1). Precipitation for the entire study period was about 20% below normal with most of the deficiency occurring from mid October through December. Even though winter pasture yields were acceptable, they were below levels that have been previously observed at this location. Winter annual pastures were almost entirely annual ryegrass due to very poor emergence of the winter rye. Winter annual pastures continued active growth until mid-December (Figure 2) while stockpile pastures appeared to have reached their maximum yield by mid-November(Figure 3). Little dry matter yield loss occurred in the winter annual pastures from the end of growth in mid-December until cattle were removed in mid-February when the pastures had been fully utilized. What appeared to be a trend toward declining dry matter yield in the stockpile pastures may actually have been a reflection of landscape position on forage yield. The increase in stockpile yield observed late in the season and shown in Figure 3 is largely explained by the final forage strips being in lower lying areas where soil moisture may have been more favorable while the late-December and January paddocks were on higher, drier landscape. Without beginning and end-of-growing-season forage measurements at each location, it is not possible to assess how much yield loss actually occurred over the winter.

Photo 3. Annual ryegrass before grazing on November 16, 2001.	Photo 4. Annual ryegrass residual after grazing on November 19, 2001.

Post-grazing residual for winter annual pastures averaged 1073 lb/acre with a mean residual height of 2.8 in. Recent work by Dr. Rob Kallenbach, MU State Extension Forage Specialist, has shown that spring yield of annual ryegrass is significantly affected by winter grazing height. Grazing below three inches reduces yield potential slightly while grazing below two inches significantly reduces spring growth rate. Residual yield on stockpile pastures was 1155 lb/acre with a residual height of 2.6 in. Winter residual has been shown to have minimal effect on spring growth of tall fescue, but other species in the pasture mix may be affected.

Photo 5. Stockpile pasture on March 8, 2002.

Winter annual pastures were fertilized with 60 lb N/acre in late March with grazing anticipated to resume in early April with weaned calves from all wintering treatments pooled to fully utilize spring ryegrass growth. Stockpile pastures were overseeded with six lb/acre red clover following completion of grazing. Sward conditions resulting from winter grazing should be very favorable for red clover establishment.

Figure 2. Pre-grazing and post-grazing forage availability for winter annual pasture remained fairly consistent throughout the study period.

Cow and calf performance: Cow and calf performance were both significantly affected by winter forage treatment (Table 1). During the respective study periods, cows on both winter annual and stockpiled pastures gained weight while cows on hay lost weight. From November 14 until winter annual pastures were fully utilized on February 15, cows gained 1.55 lb/day. This period covers peak lactation and breeding season during winter making the results even more impressive. During the same period, cows on stockpiled pasture gained .44 lb/day. Because cows remained on stockpile pasture for more than a month longer than cows on winter annual pastures, the total weight gain by cows on stockpile pasture was only 0.1 lb/day. Most of the gain by cows occurred during the first 56 days and was followed reduced gains or loss during the latter part of the study.

Figure 3. Pre-grazing and post-grazing stockpile forage availability.

Cows consuming hay lost significantly more body condition than cows on either pasture treatment. Cows on winter annual pasture exhibited not change in BCS from beginning to end of the study. Although BCS increased during November and December and then declined in January and February, BCS at beginning and end of the study were similar. Cows grazing stockpiled pasture lost one full BCS unit from beginning to finish, a period of 125 days. Cows on only hay lost nearly two full BCS units, dropping from 7.6 at the beginning of the study to 5.7 at the end.

From February 15 to March 22, cows that had been on winter annual pastures but were moved to hay feeding lost 2.7 lb/day during that 35 day period. Cows that continued to graze stockpile during the same time period lost 1.5 lb/day while cows that had been on hay all winter lost 1.02 lb/day during the same period. In all treatments, cows maintained acceptable BCS. Cows had not yet been preg checked at the time this report was prepared.

Photo 6. Stockpile residual on March 11, 2002

Calves on winter annual pastures gained significantly faster than either of the other groups during the 93 days they were on their treatment pastures. Calves on stockpile pastures gained significantly more than calves in the hay group, in spite of calves in hay group receiving creep feed. Calves in the hay group had consumed approximately 240 lb of creep feed per head through March 1. During the period from removal from pasture on February 15 until March 22, ADG for calves in the winter annual group dropped from 2.45 lb/day to 1.3 lb/day, even though access to creep feed was available after February 15. The decline was likely due to change in environment and social status and loss of milk production when the quality of their dam's diet was reduced so significantly. Adaptation to creep feed had probably not taken place when the calves were weighed on March 22. Calves who had been on hay all winter and had become accustomed to creep feed gained 2.02 lb/day during the same period. A good assessment of total winter performance is ADG from birth. This accounts for time on common pasture before the herd was sorted for the study and time on hay after removal from the study. From birth, ADG was 2.34, 2.29, and 2.07 for the winter annual, stockpiled tall fescue mixture, and hay treatment groups, respectively.

Winter feed costs: The primary objective of this research was to identify lower cost wintering systems for fall calving beef cows as alternatives to hay feeding and creep feed for calves. Stockpiled tall fescue dominant pastures have been shown to provide low cost opportunity for wintering dry, pregnant spring calving cows. There has been some question whether stockpiled pasture would provide adequate nutrition for lactating cows during the winter months. The first year of this study has clearly shown the adequacy of the diet. The primary input cost for stockpiled pasture is nitrogen fertilizer. Winter annual pastures offer a much higher level of nutrition but come at a much higher per acre cost than stockpiled pasture. If used as a transition for converting infected tall fescue to some other type of pasture, some of the cost for winter annual pastures can be assigned to permanent pasture establishment. In this study, winter pasture establishment costs include Roundup® for killing the existing tall fescue, no-till drill, seed, and fertilizer. Utilization costs were identical for both types of pasture and include two sets of temporary fence and labor for moving fences every three days. Hay cost was based on typical custom rates, yields, and fertilizer replacement rate.

Time required for moving polytape with step-in posts was recorded on two days. With one person doing the entire job including reeling up tape and pulling posts on same trip and the unreeling tape and placing posts on a return trip, the average tine required to take down one tape and erect a second tape approximately 400 ft distance was less than seven minutes when the ground was not frozen. Frozen ground increased time required to about 12 minutes. The labor charge shown in Table 2 allows for 30 minutes per pasture move at $10/hour wage based on moving every three days. The fence cost is based on retail price for a standard fence reel with 660 ft of high grade polytape and ten step-in posts prorated over an estimated five-year useful life span. At FSRC we have many reel-and-tape sets that have been in use for over ten years, including both winter and growing season use. Thus, the fence and labor costs are upper end estimates. Hay feeder cost is based on a useful life of seven years and feeding 40 bales per winter per ring at a purchase price of $150. All estimates are based on land, forage, and labor requirements for a 100-cow herd.

Conclusions:While establishment cost for winter annual pasture may be a deterrent for many producers, use of winter annual pastures provided cow maintenance and calf growth for little over half the cost of the hay based system. Few producers realize the actual cost of making hay and the low quality of what may appear to be acceptable hay. Stockpiled tall fescue pastures was adequate for maintaining cows in acceptable body condition for breeding and provided calf gains superior to hay plus creep feed at substantially lower cost. This study will be repeated two more winters and we will hopefully experience more severe weather.

Photo 7. Hay was fed to fall-calving cows using the space-bale feeding system to reduce labor requirements.	Photo 8. Creep feed was available to hay treatment calves from early January through March.

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