Home | 2008 Annual Report

UTILIZING ANNUAL FORAGES TO EXTEND GRAZING

B. W. Neville1, D. L. Whitted1, P. E. Nyren2, G. P. Lardy1, and K. K. Sedivec1

1Department of Animal and Range Sciences, North Dakota State University, Fargo, ND

2 Central Grasslands Research Extension Center, Streeter, ND


Summary: The objective of this research was to determine the effects annual forage type on beef cow performance under grazing conditions during the fall and early winter in North Dakota.  One-hundred fifty-nine mature, pregnant Angus- Simmental cross beef cows  initial BW (1174 ± 93 lb) and initial BCS (5.29 ± 0.41) were assigned to graze one of four treatment forages 1) foxtail millet, 2) turnips, 3) a forage mix (café), or 4) standing dormant native range.  The café mixture consisted of turnip (Brassica rapa var. rapa), forage radish (Raphanus sativus), cowpea (Vigna unguiculta), soybean (Glycine max), sunflower (Helianthus annuus), and foxtail millet (Setaria italica).  Cows were weighed on two consecutive days at the beginning and end of the trial, a single day BCS was also collected at these times.  Forage sampling for production data began 7-September and was conducted through out the study by clipping 0.25 m2 plots.  Forage production at the time stocking rates were calculated was 2305, 5013, 2400, and 5225 lb/ac for café, foxtail millet, native range, and turnips respectively.  Desiccation and, to a lesser extent, grazing by wildlife decreased the amount of cowpeas, soybeans, and sunflowers present in the café pastures as the grazing season progressed.  Cow BW increased 2.0 ± 0.35 lb·hd-1·d-1; however, these ADG did not differ (P = 0.29) between treatments.  While there were no treatment differences in ADG; this data indicates that any of these annual forages would be an acceptable alternative to grazing native range during the early winter.  Calculated costs for grazing forages were $0.75, 0.83, 1.80, and 1.27 hd·d-1; respectively for foxtail millet, turnips, café, and native range.  Given that both the foxtail millet and turnips produced more forage than café and that there were no statistical differences observed in cow performance; producers could benefit from increased stocking rates when utilizing these annual forage crops in their livestock production systems.  Additionally, further research is needed to find more cost affective forage mixtures in order to make them more economically feasible.

 

Introduction

Livestock producers continually try to extend the grazing season with the knowledge that extending grazing reduces feed costs (D’Souza et al., 1990; Adams et al., 1994).  Allowing cattle to graze stockpiled perennial forages decreased the amount of hay needed to maintain body condition (Hitz and Russell, 1998).  Grazing annual forages is another such way to not only graze livestock longer into the fall or early winter, but also provides potentially higher quality forages.  Brassicas, such as turnips, are one example of an annual forage that can be effectively grazed by sheep (Koch et al., 2002) or cows.  A warm-season annual, foxtail millet has previously been evaluated as a standing, bale-fed, or swath-grazed forage (Munson et al., 1999) for wintering beef cows.  More recently, forage mixtures often including warm-season annual grasses, legumes, and Brassicas have received more interest; not only because of  benefits to cattle performance, but also possibly improving soil health.  These benefits include reducing soil compaction and nitrogen scavenging and addition to the soil (Sustainable Agriculture Network, 2007).  We know of no published literature comparing cow performance when mixtures of these species are grazed (turnips, foxtail millet, and annual grasses); therefore, our objective was to determine the effects annual forage type on beef cow performance under grazing conditions during the fall and early winter in North Dakota.

 

 Materials and Methods

This study was conducted at the Central Grasslands Research and Extension Center (CGREC).  One-hundred fifty-nine mature, pregnant Angus- Simmental cross beef cows were stratified by initial BW (1174 ± 93 lb) and initial BCS (5.29 ± 0.41) and assigned randomly to graze one of four treatment forages from 16-October to 27-Novermber, 2007.  At the beginning and end of the trial two day body weights and BCS (Wagner et al., 1988) were collected.  Treatments were: 1) foxtail millet (Setaria italica); 2) turnips (Brassica rapa var. rapa.); 3) a forage mix (café) consisting of turnip (Brassica rapa var. rapa), forage radish (Raphanus sativus), cowpea (Vigna unguiculta), soybean (Glycine max), sunflower (Helianthus annuus), and foxtail millet (Setaria italica); or 4) standing dormant native range (which was the control).  The most prevalent species on native range were previously described by Hirschfeld et al. (1996) and were blue grama (Bouteloua gracilis), needle and thread (Heterostipa comata), sunsedge (Carex heliophila), western snowberry (Symphoricarpos occidentalis), and Kentucky bluegrass (Poa pratensis).

Forage establishment

Seeding of annual forages occurred on July 13th.  Seeding rates for foxtail millet and turnips were 20 and 3.5 lb/ac, respectively.  The cafeteria treatment pasture was seeded with the seed mixture containing 20, 15, 4, 1, 1, and 0.5 lb/ac for soybean, cowpea, foxtail millet, sunflower, radish, and turnip respectively.   At time of seeding fertilizer 50 lb/ac (2/3 urea, 1/3 N 11: P 52) was applied.  Rainfall events totaled 2.98, 3.9, 2.01, and 1.5 in/month for July, August, September, and October respectively (NDAWN, 2008); these totals were on average 0.7 in/month below the previous five year average for this area. 

Forage sampling

Forage sampling for production data began 7-September and was conducted a total of twice prior to grazing.  At each pre-grazing sampling date 10 0.25 m2 plots were clipped per paddock, or 30 plots per treatment.  Turnip plots were sorted for turnip tops and bulbs, as well as other forbs and grasses.  Café plots were sorted by species contained within the mixture, as well as other grasses and forbs.  Native range was split into grasses and forbs, while the foxtail millet was not separated due to the limited amount other species present.  Forage samples were collected at the initiation of and then weekly throughout grazing period.

Animal grazing

Electric cross fencing was used to limit access in an attempt to increase forage utilization.  The first area grazed was immediately adjacent to water source, and cross fences were moved to allow access to water and previously grazed areas.  Native range treatment groups were allowed to graze entire pasture simulating a typical fall-winter management scenario.  Cattle grazing turnips were offered oat straw on a free-choice basis to prevent digestive upset commonly associated with Brassicas.  Water was provided in stock tanks, which were filled daily.  Stock tanks were heated with propane tank heaters to allow cattle constant access to water. 

Stocking rates were determined based on forage production and estimated utilization.  We estimated cattle would consume 35lbs/hd/d and utilize 70% of all forage in the café, 70% of the foxtail millet, 25% of the grasses and 15% of the forbs in the native range, and 90% of turnip foliage and 30% of turnip bulbs in the turnip paddocks. 

Economic analysis

Rental and custom rates were used to calculate cost of forage establishment.  The costs used were $14.03/ac and $40.08/ac for land rental of non-irrigated pasture and non-irrigated cropland, respectively (NASS, 2007a).  Custom rates for tillage, spraying, and planting were determined from NASS (2007b). 

Statistical analysis

Cow performance data was analyzed as a completely random design using GLM procedures of SAS (SAS Inst. Inc., Cary, NC).  The experimental unit was paddock, and treatment was forage type. Statistical analysis was conducted for differences in initial BW, initial BCS, final BW, final BCS, ADG, and BCS change.  Initial BW was tested as a covariant and was not significant, thus it was removed from the model.

 Results and Discussion

Forage Production and Composition

Forage production at the time stocking rates were calculated was 2305, 5013, 2400, and 5225 lb/ac for café, foxtail millet, native range, and turnips respectively.   However, certain species such as turnips continued to grow into the grazing season as evidenced by increased production numbers (data not presented).  Percent composition of the café treatment pastures is presented in Table 1.  At the time stocking rates were calculated, 4-October, average production was 22.7, 1075.1, 65.0, 50.2, 222.2, 230.8, and 637.2 lb/ac (DM basis) for cowpeas, foxtail millet, radish, soybean, sunflower, turnip tops, and turnip bulbs respectively.  Desiccation and, to a lesser extent, grazing by wildlife decreased the amount of cowpeas, soybeans, and sunflowers present in the café pastures as the grazing season progressed.  In fact, cowpeas had all but disappeared from the café treatment at the time grazing began; while soybean disappeared by 31-October.  Other constituents such as radish and naturally occurring forbs also nearly disappeared by the end of the grazing season.   The fact that cowpeas and soybeans disappeared prior to the beginning of or during the grazing season further illustrates that these species may not be well suited for this type of grazing or at least under the conditions present in this study.  Further alterations in seeding rates, soil preparation, or fertilization could change these outcomes.  Forage quality at the beginning of the grazing season is presented in Table 2.  Crude protein values for all forages were above the 7.0% CP requirement for mature gestating beef cows listed by NRC (1996).  At the time of publication, laboratory analysis for forage samples collected during the grazing season had not been completed.  

 

Table 1. Species composition (% of total DM) of Café treatment pastures over time at Central Grasslands Research Extension Center, Streeter ND in 2007

 

Date

 

7-September1

4-October1

16-October2

31-October2

11-November2

Cowpea (%)

1.8

1.5

0.3

0.0

0.1

Foxtail Millet (%)

45.0

52.5

45.8

57.0

30.0

Other Forbs (%)

13.5

3.8

2.0

1.0

0.0

Radish (%)

5.0

3.6

5.9

1.8

0.3

Soybean (%)

7.0

3.7

3.8

0.0

0.5

Sunflower (%)

13.7

8.3

6.4

10.8

5.6

Turnip Tops (%)

14.0

9.1

17.8

10.6

8.3

Turnip Bulbs (%)

-

17.5

18.1

18.8

55.3

1 Samples collected prior to grazing (n=10/paddock).

2 Samples collected during grazing study (n=3/paddock).

 

Table 2. Forage quality of annual forages and native range at the initiation of grazing (16-October) at Central Grasslands Research Extension Center, Streeter ND in 2007

 

Treatment1

 

Café2

Foxtail Millet

Native Range

Turnips

Crude Protein (%)

10.13 ± 0.34

12.02 ± 0.36

8.15 ± 1.44

13.61 ± 1.96

NDF (%)

41.92 ± 3.16

61.74 ± 1.93

65.26 ± 2.85

21.58 ± 0.95

ADF (%)

23.83 ± 1.62

33.02 ± 1.10

36.16 ± 0.76

16.98 ± 1.23

IVDMD (%)

74.18 ± 1.18

64.72 ± 1.86

50.59 ± 0.44

87.00 ± 1.05

IVOMD (%)

58.53 ± 5.13

63.65 ± 1.59

50.80 ± 0.90

87.70 ± 0.50

Ca (%)

1.46 ± 0.45

0.45 ± 0.05

0.54 ± 0.10

1.47 ± 0.33

P (%)

0.38 ± 0.01

0.25 ± 0.02

0.15 ± 0.01

0.38 ± 0.03

1 Weighted means (mean ± standard deviation).

2 When insufficient sample was present to analyze for the value of interest an average of the remaining values was used.

 

Cattle Performance

Initial BW was affected (P = 0.005; Table 3) by treatment.  This is likely due to cattle being stratified from a weight taken 5 d prior to the initiation of this study.  Weights reported in this study did not include this weight but, rather the average of a two day weight taken one day prior to and the day of initiation of this study.  Cow BW increased 2.0 ± 0.35 lb·hd-1·d-1; however, these ADG did not differ (P = 0.29) between treatments.  While there were no treatment differences in ADG; this data indicates that any of these annual forages would be an acceptable alternative to grazing native range during the early winter.  There were increases in BCS for café and foxtail millet grazed cows when comparing initial and final BCS (5.27 vs. 5.63; P = 0.004 and 5.30 vs. 5.57; P = 0.05); however, a difference between treatments for either final BCS (P = 0.31) or change in BCS (P = 0.10) could not be established.  Interestingly, the foxtail millet and café grazed cattle had numerically lower ADG, but numerically greater change in BCS.  The differences are likely due to nutritional differences between forages that occurred as the grazing season progressed.  Differences between café and foxtail millet could be due, in part, to variability in forage DM between treatments, as well as the intake of oat straw for turnip grazing cows leading to increased gut fill. 

Table 3. Performance of beef cows grazing annual forages and native range at Central Grasslands Research Extension Center, Streeter ND in 2007

Café

Foxtail Millet

Native Range

Turnips

SE

Treatment

P-value

Initial BW, lb

1176ab

1182a

1168b

1168b

2.22

0.005

Initial BCS

5.27

5.30

5.38

5.22

0.04

0.15

Final BW, lb

1258

1251

1255

1263

9.55

0.85

Final BCS

5.63

5.57

5.47

5.48

0.06

0.31

ADG, lb

1.94

1.65

2.07

2.27

0.22

0.29

ÄBCS

0.36

0.26

0.10

0.26

0.06

0.10

abc Means are different at P < 0.05.

 

Economic Comparison

Calculated costs for grazing forages were $0.75, 0.83, 1.80, and 1.27 hd·d-1; respectively for foxtail millet, turnips, café, and native range. Much of the increased cost for grazing the café mix of annuals was incurred due to the inclusion of soybeans and cowpeas.  These two forages increased seeding costs by $11.70/ac, while providing little to the total forage production of the café paddocks. It is not known how much these legumes contributed to the production of the other annual species due to their ability to fix nitrogen. Further use of more cost effective legume species, such as red clover, may increase the cost effectiveness of these forage mixtures.  Additionally, the application of this type of grazing in a double-cropping system, where a forage crop is removed prior to planting of the winter pasture forage could prove more economically beneficial. 

 

 Implications

Given that both the foxtail millet and turnips produced more forage than café and that there were no statistical differences observed in cow performance; producers could benefit from increased stocking rates when utilizing these annual forage crops in their livestock production systems.  Annual forage mixes, like the café treatment, show promising results when considering beef cow performance; however work is needed to decrease the cost of planting these mixtures to make application more economical.

 Present Progress

In 2008 our café mixture of annuals was changed in an effort to increase forage production.  The new mixture included sorghum sudan, turnips, forage radish, sunflowers, triticale, and red clover.  Additionally, forage barley was planted and harvested prior to planting of the winter forages; this was done to help defer the economic cost of land rental to the hay crop instead of placing it solely on the grazing.  Unfortunately at the time of publication no results from our 2008 work were available. 

 Literature Cited

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D’Souza, G. E., E. W. Marshall, W. B. Bryan, and E. C. Prigge. 1990. Economics of extended grazing systems. Am. J. Alternative Agric. 5:120-125.

Goering, H. K., and P. J. Van Soest. 1970. Forage fiber analyses (apparatus, reagents, procedures, and some applications). Agric. Handbook No. 379. ARS-USDA, Washington, D.C.

 Hirshfeld, D. J., D. R. Kirby, J. S. Caton, S. S. Silcox, and K. C. Olson. 1996. Influence of grazing management on intake and composition of cattle diets. J. Range Manage. 49:257-263.

 Hitz, A. C., and J. R. Russell. 1998. Potential of stockpiled perennial forages in winter grazing for pregnant beef cows. J. Anim. Sci. 76:404-415.

 Jensen, R. E. 1972. Climate of North Dakota. N.D. National Weather Service, North Dakota State University, Fargo, ND.

 Koch D. W., C. Kercher, and R. Jones. 2002. Fall and winter grazing of Brassicas- a value-added opportunity for lamb producers. Sheep and Goat Res. J. Vol. 17. No. 2:1-13.

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Munson, C. L., J. C. Whittier, D. N. Schutz, and R. L. Anderson. 1999. Reducing annual cow cost by grazing windrowed millet. Prof. Anim. Sci. 15:40-45.

National Agricultural Statistics Service (NASS). 2007a. North Dakota 2007 County Rents and Values.  Fargo, ND. http://www.nass.usda.gov  Accessed Feb 1, 2008.

National Agricultural Statistics Service (NASS). 2007b. 2007 North Dakota Custom Rates, Part I Early Season Operations.  Fargo, ND. http://www.nass.usda.gov  Accessed Feb 1, 2008.

North Dakota Agricultural Weather Network (NDAWN). 2008. North Dakota State Univ., Fargo, ND. http://ndawn.ndsu.nodak.edu  Accessed Feb 1, 2008.

National Research Council. 1996. Nutrient requirements of beef cattle: Update 2000. National Academy Press. Washington D.C.

 Robertson, J. B., and P. J. Van Soest. 1991. Methods for dietary fiber, neutral detergent fiber, and non-starch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74:3583-3597.

Sustainable Agriculture Network. 2007. Managing cover crops profitably. Third Edtion. Beltsville, MD.

Tilley, J. M. A., and R. A. Terry. 1963. A two stage technique for the in vitro digestibility of forage crops. J. Br. Grassl. Soc. 18:104-111.

Wagner, J. J., K. S. Lusby. J. W. Oltjen, J. Rakestraw, R. P. Wettemann, and L. E. Walters. 1988. Carcass composition in mature Hereford cows: Estimation and effect on daily metabolizable energy requirements during winter. J. Anim. Sci. 66:603-612.


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