Winter Grazing of Ewes on Inter-Seeded Forage Corn and Kale

Final Report for FNC01-366

Project Type: Farmer/Rancher
Funds awarded in 2001: $1,600.00
Projected End Date: 12/31/2003
Region: North Central
State: Wisconsin
Project Coordinator:
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Project Information


I operate a commercial ewe flock, currently comprised of 380+ prolific, white faced ewes with Finnish Landrace, Rambouillet, Texel and Charollais breeding. I rent the family farm which has about 105 acres of permanent pasture and 135 acres of crop ground. Fenced stream buffers and wooded areas reduced the useable pasture acres to about 90. crop ground, not required for the flocks hay and grazing needs, is cash rented, all crop work is hired. Ewes are managed on rotationally grazed pasture and crop residue for roughly 240 days/year. Hay feeding on winter pasture occurs for approximately 85 days, with roughly 40 days of barn feeding immediately prior to and during the lambing season.

Rotational grazing has been practiced on this farm for the past 13 years. I also converted the crop ground into contour strips and began installing stream fences and buffers about 11 years ago. I’ve also been doing my own farm trials looking at incorporating grazing and haying of alfalfa and it’s affect on stand longevity.

A disadvantage for upper Midwest grazers is the winter flat spot, where climatic conditions (snow) reduce the opportunities for grazing, thus creating a need to rely on more stored feeds. This increases costs of production relative to other regions and countries with milder winter conditions, and hence longer grazing and growing seasons. Feeding hay over winter represents a significant expense for our sheep operation compared to grazing. Grazing costs currently run in the .8 cents/lb of Dry Matter or a 3.2-4 cents/ewe/day cost of range while hay cost average 2.5-3 cents/lb of DM or 10-12 cents/ewe/day.

With stockpiled forages and crop aftermath, grazing can be easily extended beyond the average killing frost date into December. Sheep can and do graze effectively through snow if there is an adequate quantity of forage available. However traditionally stockpiled forages (cool season grasses and legumes) can become unavailable when snow depths either exceeds 10-12” or when the snow develops a hard crusted layer.

The unpredictability of the onset of this period makes feed budgeting difficult. One season snow depth may make grazing impossible in early December, another year grazing may continue into January and beyond. On average, Iowa County receives 3.2 inches of snow in November, 8.1 inches in December and by January another 9 inches of snow, our seasonal average is 40”. Our experience grazing sheep for the past decade suggests that snow conditions prevent grazing sometimes between December 20 and January 1. This leaves approximately 85 days where snow cover makes hay feeding our best current option.

In order to continue grazing through periods of deep snow, the forage must meet the nutritional requirements of the animal, and be able to stand through or above the snow depth, and hence be accessible to livestock. This project examined the suitability of inter seeding forage corn and narrow stem kale in meeting this criteria and being available for grazing when snow conditions prevent grazing of traditional stockpiled forages and in meeting the nutritional requirements of mid-gestation ewes.

This grant was used to establish 10 acres of corn/kale for the purpose of stockpiling for winter grazing. It covered land lease costs, soil tests, fertilizer, seed cost, herbicide, tillage and planting, portable fencing and multiple forage analysis and yield checks.

The forage analysis and yield check will provide details on how well this crop is meeting the nutritional requirements of mid-gestation ewes according to NRC recommendations, indication when or if additional supplementation may become necessary.

Two potential crop fields were soil tested in the fall of 2001. Field number 2-9.8 acres was selected as the demonstration field. This field had been in an alfalfa/grass rotation for the previous 5 years and was reasonably accessible to gates between pasture and the cropped area of the farm. Field 2 was sprayed with Round-Up Ultra on May 3. Since this was the first year corn field, I decided against applying any insecticide.

Spring 2002 weather was wetter and cooler than normal creating some delays in planting. Summer arrived early in June and brought with it warmer and drier temps the norm.

Rain, Departure, snow fall, temp, departure
April: 3.45, 0.1, -, 46.8, 0.9
May: 2.92, -0.33, -, 53.4, -4.3
June: 3.7, -0.35, -, 68.8, 1.8
July: 2.06, -1.87, -, 74.1, 2.5
August: 3.04, -1.29, -, 69.5, 0.4
September: 2.74, -0.34, -, 64.2, 3.5
October: 2.1, -0.08, 0.3, 44.8, -4.5
November: 1, -1.3, 1.2, 34.3, -1.2
December: 0.67, -0.99, 1.6, 27.4, 4.4
January: 0.36, -0.89, 4.4, 17.7, 0.4

Temperatures and moisture moderated a bit by the end of July, remained above the norm in temperature and below the norm for moisture through the fall and early winter period. While June appears to be near normal for precipitation, the monthly total fell within the first 10 days of June, with most of the July rains occurring after the 20th, leaving and extremely dry and hot 7 week stretch.

Table 1 is a summary of the soil tests analysis and recommendations
N, P2O5, K2O
Corn: 120, 0, 50
Brassica’s: 100, 15, 60
220, 15, 110
75% rate: 165, 11.25, 82.5

Adding both nutrient requirements together seemed inappropriate since both crops would be in some competition with each other, with neither reaching the maximum yield as in a mono-culture situation which the recommendations are based. After consulting with our county Ag extension agent, Rhonda Gildersleeve, I guessed that each crop might yield 75% of its maximum given the competition, and adjusted the fertilizer rate accordingly. Fertilizer was spread on May 10, and tilled on May 15.

For forage corn I selected Baldridge Hybrids 105gt, this variety has been selected for is suitability for grazing, and offered higher digestibility, protein and energy compared to traditional grain varieties. At the time of writing the initial grant, the plan was to utilize Kapeti Kale, a giant narrow stemmed kale developed and imported from New Zealand. This kale would normally be expected to grow to about 30+” tall, however poor growing and harvesting conditions in New Zealand made the seed unavailable in the US in time for this grant. The alternative kale selected was Kestrel a medium variety also developed in New Zealand but which only grew to about 16”. Normal plant populations for corn would be upwards of 30,000, however with the goal of inter-seeding another crop, the population was back down to about 24,000. Corn was seeded in 30” rows on May 20. Kale would normally be seeded at 4 lbs/acre, and for the trial back off to 3 lbs/acre. This was drilled into the corn on May 27 on 7” spacing. The week delay in kale seeding was to ensure the corn germinated first. My concern was the kale would germinate and quickly close the canopy and shade out the corn seedlings due to the narrow rows and broad leaves before the corn seedlings could above the kale plants.

The canopy closed early in July, with the kale creating a total shaded under story, providing good weed suppression until late July. The first killing freeze didn’t occur till October 15, about 5 days later than our average. The first forage samples were collected on October 28 with the assistance of Iowa County Agriculture Agent Rhonda Gildersleeve, Ms. Gildersleeve recommended having a wet chemistry analysis done on the samples, rather than the NIR, which would be more accurate.

Alfalfa and corn fields above and below the trial field were grazed from October-December. Field 2 was subdivided utilizing portable electric fencing into 4 paddocks. 65 random ewes were identified, marked, weighed on December 23. 260 ewes and 8 rams were introduced to the first paddock later on the 23rd. a second forage sample was taken on January 22. a post grazing sample was collected on the 1st and 4th paddocks to try and assess utilization and waste. Ewes were rotated through the paddocks and were removed from field 2 on January 31 previously ID’d ewes weighed again on February 1.

Results and Discussion:
Spring 2002 weather was cool and wet delaying corn planting by about 14 days. Conditions in June quickly dried out and heated up. With below normal precipitation and above normal temperatures. By mid July, the corn was showing signs of drought stress as the leaves were beginning to curl to conserve water. Corn started to tassel the 20th July. Temperatures moderated in late July and August and a couple of light but very timely rains occurred, rescuing the crop, there is no estimate for the reduction in yield. The kale was showing no signs of stress during this period. However, by late July a large infestation of alfalfa worms had taken over the kale consuming close to 100% of the leaves, leaving the fleshy stem. A rescue insecticide application was not feasible because of the height of the corn. Regrowth of the kale was also limited because of shading form the now tall corn plant. There was not a pre insect estimate of the kale yield. By mid-September, visually, the kale looked to only have recovered maybe 10% of its dry matter; yield estimates would confirm that assessment. An article on grazing brassica’s from Ohio State University suggests that insect problems on brassica’s are rare and unpredictable on a year to year basis.

The outside rows of the field had higher amounts of kale because of better sunlight penetration. The first forage sample was collected by entering the field about 7 rows and collected a square yard of plants. Plants were counted, weighed and separated into their components then samples submitted to the University of Wisconsin Soil and Forage Lab at Marshfield for wet chemistry analysis.

My presumption was the ewes would show most interest in consuming the kale, corn leaves and grain portion of the plants. The stalks, while having some feed value would be less likely to be consumed by the sheep, however these were tested also, because of the potential application this practice could have for beef production. Yield of the kale was very low following the insect problem, estimates put yield at less than 350 lbs/acre, when closer to 4500 lbs would have been expected at 75% yield.

Mother Nature did not sign on as a grant partner and turned out to be very uncooperative. By the end of December we were facing on open winter, at that point, the seasonal snow total of 3.1 inches was about 17 inches below normal, and had all melted. I made the decision to go ahead and start the grazing trial and hope for snow during the course of the trial. There were several very light snow falls, but no the depth I wanted to evaluate the effectiveness of this grazing regime under deep snow conditions.

Portable electric fencing as used to subdivide the field into 4 sections and 260 ewes and 8 rams were introduced on December 23 to first section of corn/kale. The mature ewes are familiar with foraging for corn after harvesting, but the yearling ewes were having a first time experience. Standing corn however was a newer experience for all. The first two days were spent along the outside of the strip grazing grasses and kale, with much time spent wandering back and forth across the field. It was the 3rd day before the flock ventured deeper into the stand of corn, which appeared to create high trampling losses. Walks through the area the sheep had visited revealed zero remaining kale, some corn leaves consumed and much corn still in the husk. The husks dried enough to be open were eaten but the wetter corn with the husk tightly closed was largely untouched. By the 10th day on the 1st paddock, the flock was beginning to exhibit better utilization on both leaves and learning how to open the tighter corn husks. Ewes were given the 2nd area on January 5, the 3rd area on January 14 and the final section on January 23. Utilization appeared to improve with experience with the 3rd and 4th moves showing the best utilization. A post grazing sample was collected on the first and last section to try and estimate if the utilization had improved as the flock became more adept at grazing a new crop. Waste on the 1st and 2nd moves appear exceptionally high. In hind sight, the ewes should have been given a smaller paddock break first to allow them to better acclimate to grazing the corn, which would reduce wastage.

A 2nd forage sample was collected on January 22 to see what yield and quality looses were occurring in the field.

Our first sample of kale included only the leaf and stem and not the stalk portion, in post grazing observations I couldn’t find any kale stalks and realized the ewes were consuming the entire plant. So the second forage sample included the central stalk after observing ewes consuming entire plants. This while useful for quality data, distorted the yield data. My other observation regarding kale was that without the protection of snow cover, if begins to dessicate and loose color. Despite its desiccated appearance still maintained a reasonable amount of forage quality.

The quality of the kale was about what I expected. I was surprised at some of the corn results. In the 1st forage sample, the grain portion tested 15.6% crude protein when adjusted on dry matter basis, and the leaves at 8.8% crude protein, the leaves were slightly deficient in protein for mid gestation ewes, but were almost close enough to meet their nutritional needs.

The kale was readily and completely consumed right from the start of the trial. The ability to forage for the grain portion improved over time as well as adapting to eating corn leaves. After completing this project, I had the opportunity to listen to Dr. Fred Provenza from Utah State speak on grazing behavior, and their research suggests that animals may take up to 3 weeks to learn new grazing treatments. The apparent increase in kale yield was due to sampling the entire plant in January, rather than just the leaves and stem. There is some loss in quality and in amount of forage leaving it in the field, there was still adequate amounts to easily feed the flock.

On December 23, at the beginning of the grazing trial, 65 ewes were weighed, averaging 144 lbs (range 101-177 lbs) and ages 18 months to 9 years. Grazing was completed on January 31, 2003 the ewes were brought to the handling facilities and the same 65 ewes re-weighed on February 1. At this point the average weight was 160.5 lbs representing a 16.5 lb average gain over the 39 day trial. Weight changes range from -6 lbs to +36 lbs. median gain was 17 lbs and mode was 13. Nutritionally, the diet was very adequate. The idea for including kale as an inter seeded species was as a means to ensure an adequate level of protein in the diet, however wet chemistry analysis of the grazing corn showed it would be quite adequate for mid gestation ewes.

Project Impacts:
The cash cost to establish the crop was $211/acre. While I did incur some additional expenses in extra fencing to insure that only the project field was harvested, most of the portable fencing already was available used during the regular grazing season, but was not included as crop production expenses, presuming most other grazers would also already have this investment made. So, 268 head were fed for 39 days (animal 110452 grazing days) at a cost of $2110. Over the course of this project, this works out to be about 20 cents/head/day cost, considerably higher than our current 10-12 cents/head/day expense with hay feeding.

There are three points to make here: 1) kale yield was greatly reduced due to the insect problem, had this been more normal, grazing days and I suspect ewe gains would have been higher, weight gain was already a little more excessive than I would typically want for this period 2) the Shepard (me) grossly underestimated the amount of time it would take for the ewes to adapt to this new forage and how to graze it. The initial 1-2 grazes should have been much smaller paddocks reducing the waste and increasing grazing days. 3) Being unsure of the suitability of this and whether the ewes were losing, holding or gaining condition. I moved the flock sooner than they probably needed to be moved.

My feeling during the course of the grazing portion of the project was that harvest losses were rather high, but that over time, utilization was improving. Realize that I’m taking my best guess here, but as I look at points 2 and 3, we could/would have picked up and additional 10-14 days of grazing. If we hadn’t had the insect problem with the kale this would have contributed yet another 14-21 days of grazing. The potential of an additional 35 days grazing seems very likely which would bring down to the cost to the 10 cents/head/day range, comparable to hay feeding, but not cheaper.

We do not normally feed any grain until the final 4-6 weeks pre-lambing, so weight gain in mid-gestation is lower when feeding only hay than what we experienced for this study. Somehow the value of this added weight gain needs to be accounted for financially in making comparisons with traditional winter hay feeding regimen. That might mean analyzing feed on a cost/Mcal basis.

The main question that has not been adequately addressed by this project is the suitability of this practice for extending the grazing season under deeper snow conditions. The lack of snow cover in the winter 2002/2003 season precludes any hard data. There was some yield losses over time, and some corn did lodge and ears fall to the ground, without snow cover the sheep did find and consume these, however under snow these would have been more difficult for the ewes to dig and harvest. The majority of the corn remained standing well into January with adequate quality. The kale, even without benefit of snow cover, did maintain it’s quality reasonably well, and would have been of better quality with snow cover. Over time the flock became quite adept at grazing leaves and corn off the corn stalks and would remember this in future years. It would be suitable and possible to feed the ewe flock in winter this way, they issue that remains is it’s cost effectiveness compared to hay feeding.

There might be the possibility of a few variations to this project worth consideration. Rather than interseeding the kale and corn, would strip seeding be a viable alternative? In the event of insect damage it would facilitate treating the crop. Would this be an alternative to finishing lambs in the field rather than in a feedlot? How would grazing the corn and kale in mid summer affect total yield and regrowth into fall for winter grazing?

Another issue that I didn’t address but is worth mentioning is labor. Total time to construct temporary fencing was 2 hours, plus another 2 hours removing the fence. Daily checks to monitor the ewes were drive bys, twice weekly mineral was delivered into the paddocks and walk around to check consumption and observe the flock. Feeding hay in winter on pastures takes 20 minutes every second day, over a 40 day period I’d been looking at something around 400 minutes or around 6.5 hours.

Overall the sheep fleeces were cleaner than with hay feeding, and the manure and urine were redeposited directly onto the crop field.

We hosted a pasture walk on the 28th of September. Rhonda Gildersleeve, Iowa County Ag Agent help promote this in a news release sent to three state wide ag newspaper, Country Today, Agri-View and Wisconsin Farmer. I also posted the event on the internet on a sheep and a grazing discussion list. Twenty five sheep producers from 3 states attended the program. I was interviewed by the state age extension on this practice and my experience with SARE. Another opportunity to share the results was done via the Wisconsin Sheep Production Wis-line series. A state wide telephone network lining all county extension offices, 10 Wisconsin counties returned evaluations indicating 25 producers in attendance, 1 county from Michigan also participated.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.