MANAGEMENT STRATEGIES TO EFFECTIVELY

CONTROL LEAFY SPURGE IN RANGELAND

BY GRAZING SHEEP

Timothy C. Faller, Paul Berg, Dan Nudell

Introduction and Justification

North Dakota has in excess of one million acres of rangeland that is impacted by the presence of leafy spurge. Most of the land is controlled (owned or rented) by producers of beef cattle. Severity of infestation is impacted by waterways, overhead electrical transmission lines, railways and roadways. Presence of trees, high water tables, waterways and environmentally protected plant and animal species are constraints to the usage of many herbicides as useful control methods. Increasing leafy spurge populations has negatively impacted economic well-being of many livestock producers in North Dakota.

Feed costs is the largest single component of total cost of production faced by sheep producers. Birth rate and survivability of lambs from birth to weaning are critical factors impacting gross income and net profit for the sheep producer.

The opportunity to reduce variable costs and increase cash flow while adequately controlling leafy spurge in an environmentally friendly manner is attractive for many North Dakota livestock producers. Cattle are a poor utilizer of leafy spurge plants as components of the range composition while many species of wildlife and small grazing ruminants are a very good utilizer of leafy spurge as a component of the range setting. Many livestock producers truly do not want to get heavily involved in the production of alternative species of livestock (primarily sheep and goats). Management strategies that will allow them to integrate with existing sheep producers, or potentially establish profitable associated enterprises that will reduce the presence of leafy spurge are attractive to many North Dakota livestock producers An acceptable alternative may be to develop a cooperative structure that would establish sheep production units owned by cattle producers in areas where there are high concentrations of leafy spurge. These units might serve as a form of economic development for communities in the spurge impacted area. To do so they need a smorgasbord of alternatives and hard numbers to represent the income and expense of such proposed arrangements.

The North Dakota sheep industry provides in excess of $10,000,000 new wealth annually (1993 ND Ag Statistics). Loss to the North Dakota Ag Economy is estimated to be in excess of 70 million annually from the impact and costs associated with controlling leafy spurge (Leistritz, 1991). The loss of the Federal Wool Incentive program will negatively impact the future of sheep producers in North Dakota. The potential exists to reduce costs for sheep producers by providing no-cost or low cost summer grazing and in turn improving range production for the sake of enhancing impacted beef producer's incomes.

The Sheepbud Shepherd IMS enterprise analysis was developed to assist sheep producers evaluate the economics of their operation (Nudell, 1994). Sheepbud Shepherd IMS is presently being S.P.A. tested and will be available to be used as a method of cross referencing the different strategies developed to control leafy spurge in the rangeland.

Experimental Procedure

Actual production associated with a variety of research trials at Hettinger Research Center will be evaluated economically to provide numerous strategies to be presented to industry for application. The strategies will address three different primary approaches to incorporating small ruminant animals in grazing plans focused on controlling leafy spurge. The strategies will be categorized on the basis of intensity of sheep production. Primary focuses will be: High Intensity (HI), Traditional Approaches (TI) and Low Intensity (LI). Data will be collected on; longevity, lamb survivability and routine production measures. An initial flock of 400 ewes will be established composed of 200 each of Rambouillet and Montadale x Rambouillet ewes. Half of each group will be born in 1993 and the other half in 1994. Similar breed type yearling replacement ewes will be added annually to keep numbers relatively constant. Similar numbers from each year and breed type will be initially assigned to each of five management strategies. The five management strategies will be compared to an existent accelerated lambing flock of 500 ewes (HI).

High Intensity Approach (HI)

Rambouillet ewes and rams will be utilized to increase the incidence of out of season mating. The attempt will be to select all replacements from fall born lambs of a closed flock of 500 ewes. Ewes will be mated and allowed to lamb in January and September as often as possible. Presently this flock of ewes is lambing at 1.4 lambings annually and presenting 1.5 lambs per lambing. This provides in excess of two lambs born per ewe annually. A 56 day weaning strategy will allow ewes to graze leafy spurge infested rangeland without the presence of lambs to reduce losses to predators under both lambing times. Both sets (January lambing and September lambing ewes) will summer graze leafy spurge at the Missouri River Correctional Center (MRCC), Bismarck, North Dakota. The High intensity group will be limited to fall born ewes which are similar age to the ewes in the other groups.

Traditional Approach (TI)

Rambouillet and Montadale x Rambouillet cross ewes that lamb in January and are exposed to lamb once annually with resulting production to be weaned at 60 days of age and put in the feedlot will be compared to genetically similar ewes that will lamb in April-May, weaning weights will be taken at 60 days. Both groups will be shed lambed with half to be reared in confinement and half in outside lots.

Low Intensity Approach (LI)

Rambouillet and Montadale x Rambouillet cross ewes of similar genetic background to the TI group will be mated to begin lambing mid-may. The intent is to begin lambing on the range at the onset of the time ewes begin grazing leafy spurge. The intent of this group is to measure if the sheep operation can support itself with the primary interest being to improve the range resource for the benefit of the beef cow. Also of interest will be observing the bonding mechanism as described at the Jornada Experiment Range site in New Mexico. Bonding of sheep to cattle would be of advantage to sustaining the sheep component of this strategy.

Economic Procedure

The approach will be to measure actual production figures and imply sound economics using the Sheepbud Shepherd IMS financial analysis program to cross reference comparisons.

Duration

The data accumulated from five lambing years for each of the strategies will be utilized to evaluate economic viability of the treatments. Data from the multi-species trial will be utilized to measure effectiveness of leafy spurge control and the impact on species composition at the site. (Economic impact should be known in five years, however, it may take longer to acquire full knowledge of impact on the range site.)

1997 Results and Discussion

The results presented are preliminary and provided for discussion only. A detailed systems evaluation of the data will be conducted at the conclusion of the project. Tables 1-6 represent performance data for the ewes of the five management systems for the years 1995 through 1997. Tables 1 and 2 give production information for the various ewe types and management systems lambing in the project. Tables 3 and 4 indicate performance of the lambs born in the project to a 60 day weaning time. Lambs born and reared on grass were weighed at a similar date and left on the ewe. Table 5 indicates reproductive performance of a similar age group of Rambouillet ewes HI on an accelerated lambing project as a control and table 6 the performance of those HI generated lambs.

Tables 7-11 merge data to look at some other questions that have been popular producer questions. Again this assembly of data is for discussion purposes only as it will require at least one productive lifetime to get a feeling for differences in the systems of production.

*It should be specifically noted that there is no selection for performance during the course of this project which will account for lower production because of deficiencies in maternal traits. The only criteria for removal from the trial is failure to perform reproductivly or total lack of milk production.

Table 7 merges data for the years 1995 through 1997 for the purpose of comparing breed, lambing time and system. Table 8 merges lambing times to compare breed and system. Table 9 merges breed types and lambing time to make a comparison of systems. Table 10 merges breed type and system to compare lambing times for the MI systems and further compares that to the LI system. Table 11 merges systems and lambing time to compare breeds. The HI control group data is not incorporated in any of the merged data sets.

JANUARY LAMBING MAY LAMBING

1995-1996

1997

1995-1996

1997

Breed Type

RXR

RXR

RXR

RXR

RXR

RXR

RXR

RXR

RXR

RXR

Rearing Type

IN

OUT

IN

OUT

IN

OUT

PAST

IN

OUT

PAST

Ewe Age @ Lambing in Months

23

23

38

38

27

27

27

42

42

42

Ewes Exposed

60

59

38

39

54

58

55

32

34

33

Ewes Lambing

52

56

35

37

51

55

51

26

26

28

Lambs Born

89

91

62

65

85

86

63

32

33

28

Lambs Weaned

72

77

53

45

58

57

51

24

30

28

1.20

1.31

1.39

1.15

1.07

.98

.93

.75

.88

.85

R=RAMBOUILLET M= MONTADALE
PAST=PASTURE
IN=CONFINEMENT REARING
OUT=BARN AND LOT REARING
*NO RECORD
*ULTRASOUND UTILIZED TO DIAGNOSE DRY EWES ('96)

Table 2. Reproductive performance of Montadale-Rambouillet cross ewes under five different rearing strategies.

JANUARY LAMBING MAY LAMBING

1995-1996

1997

1995-1996

1997

Breed Type

MXR

MXR

MXR

MXR

MXR

MXR

MXR

MXR

MXR

MXR

Rearing Type

IN

OUT

IN

OUT

IN

OUT

PAST

IN

OUT

PAST

Ewe Age @ Lambing in Months

23

23

38

38

27

27

27

42

42

42

Ewes Exposed

56

53

49

41

53

53

50

36

33

40

Ewes Lambing

48

47

42

37

52

52

47

32

30

38

Lambs Born

67

67

66

58

66

68

53

38

47

42

Lambs Weaned

55

56

56

42

50

52

47

31

39

41

Lambs Weaned For Ewe Exposed

.98

1.06

1.24

1.02

.94

.98

.94

.86

1.18

1.03

R=RAMBOUILLET
M= MONTADALE
PAST=PASTURE
IN=CONFINEMENT REARING
OUT=BARN AND LOT REARING
*NO RECORD
*ULTRASOUND UTILIZED TO DIAGNOSE DRY EWES ('96)

Table 3. Performance of lambs born of Rambouillet ewes reared on five different strategies.

JANUARY LAMBING MAY LAMBING

1995-1996

1997

1995-1996

1997

Breed Type

RXR

RXR

RXR

RXR

RXR

RXR

RXR

RXR

RXR

RXR

Rearing Type

IN

OUT

IN

OUT

IN

OUT

PAST

IN

OUT

PAST

Wean Wt (Ibs.)

46.02

48.30

45.43

48.19

29.57

32.93

39.13

34.04

36.30

41.75

Wean Age Days

66.11

64.29

72.70

73.95

48.22

48.10

47.10

49.58

51.06

50.30

Wean Wt Corrected to 60 Days (lbs)

42.0

45.1

37.5

39.1

36.8

40.3

50.7

41.2

42.7

49.8

Pounds Lamb Weaned Per Ewe Exposed @ 60 Days

50.4

59.1

52.1

45.0

39.4

39.6

47.53

30.9

37.8

42.3

R=RAMBOUILLET
M= MONTADALE
Wean Age In Bold Print Calculated From Average Of Other Similar Groups.

Table 4. Performance of lambs born of Montadale-Rambouillet cross ewes reared on five different strategies.

JANUARY LAMBING MAY LAMBING

1995-1996

1997

1995-1996

1997

Breed Type

MXR

MXR

MXR

MXR

MXR

MXR

MXR

MXR

MXR

MXR

Rearing Type

IN

OUT

IN

OUT

IN

OUT

PAST

IN

OUT

PAST

Wean WT (Ibs.)

47.54

50.24

43.14

50.71

29.06

34.15

42.74

37.5

38.3

35.5

Wean Age Days

61.75

67.37

70.94

74.74

47.48

49.82

49.68

37.0

53.2

46.0

Wean Wt Corrected to 60 Days (lbs)

46.2

44.7

36.5

40.7

36.7

41.1

51.6

60.8

43.2

46.3

Pounds Lamb Weaned Per Ewe Exposed @ 60 Days

45.3

47.4

45.2

41.5

34.5

40.3

48.5

52.3

51.0

47.6

R=RAMBOUILLET
M= MONTADALE
Wean Age In Bold Print Calculated From Average Of Other Similar Groups.

Table 5. Reproductive performance of Rambouillet ewes HI on an accelerated lambing strategy.

BREED TYPE RXR



LAMBING TIME

1995

JAN/SEPT

1996

JAN/SEPT

1997

JAN/SEPT

REARING TYPE

IN/OUT

IN/OUT

IN/OUT

EWE AGE @ LAMBING TIME MONTHS

16/24

16/24

16/24

TOTAL EWES

98

121

93

EWES LAMBING

63/59

89/67

78/61

DRY EWES (BOTH LAMBINGS)

14

8

6

LAMBS BORN

81/88

114/90

113/69

LAMBS WEANED

64/76

90/86

79/55

% REARED OF THOSE BORN

79/86

79/95

R=RAMBOUILLET
IN = CONFINEMENT REARING

Table 6. Performance of lambs born of Rambouillet ewes HI on an Accelerated lambing strategy.

BREED TYPE RXR



LAMBING TIME

1995

JAN/SEPT

1996

JAN/SEPT

1997

JAN/SEPT

WEAN WEIGHT (LBS)

39.29/42.91

44.7/32.68

41.62/41.62

WEAN AGE (DAYS)

64.35/65.22

62.9/56.18

66.74/63.63

WEAN WT CORRECTED TO 60 DAYS (LBS)

36.6/39.6

42.6/34.9

37.42/39.24

TOTAL LBS OF LAMB PRODUCED PER EWE @ 60 DAYS (LBS)

56.57

56.49

54.99

R=RAMBOUILLET

* = EXTREMELY WET CONDITIONS IN LOTS

Table 7. Merged data for the years 1995 - 1997 for the purpose of comparing breed, lambing time and system.

JANUARY LAMBING MAY LAMBING

Breed Type

MXR

MXR

RXR

RXR

MXR

MXR

MXR

RXR

RXR

RXR

Rearing Type

IN

OUT

IN

OUT

IN

OUT

PAST

IN

OUT

PAST

Ewes Exposed

105

94

98

97

97

86

86

86

92

88

Ewes Lambing

90

84

87

93

84

82

85

77

81

79

Lambs Born

133

125

151

156

104

113

93

117

119

92

Lambs Born/

Ewes Exposed

1.26

1.33

1.54

1.61

1.17

1.31

1.02

1.36

1.29

1.05

Lambs Weaned

111

98

125

116

81

91

88

82

87

79

Lambs Weaned/ Ewes Exposed

1.06

1.04

1.28

1.20

.91

1.06

.97

.85

.95

.90

Table 8. Merged lambing times to compare breed and system.

BREED TYPE AND SYSTEMS

Breed Type

MXR

MXR

MXR

RXR

RXR

RXR

Rearing Type

IN

OUT

PAST

IN

OUT

PAST

Ewes Exposed

194

186

89

184

189

88

Ewes Lambing

174

166

85

164

174

79

Lambs Born

237

238

95

268

275

92

Lambs Weaned

161

150

88

207

209

79

Lambs Weaned/

Ewe Exposed

.83

.81

.99

1.13

1.11

.90

Table 9. Merged breed types and lambing time to make a comparison of systems.

LAMBING SYSTEMS

IN

OUT

PAST

Ewes Exposed

378

378

179

Ewes Lambing

338

345

164

Lambs Born

505

508

187

Lambs Weaned

399

406

167

Lambs Weaned/

Ewe Exposed

1.06

1.07

.93

Table 10. Merged breed type and system to compare lambing times for the MI systems and further compares that to the LI system.

LAMBING TIME AND SYSTEM

MI

LI

JAN (IN& OUT)

MAY (IN & OUT)

MAY (PAST)

Ewes Exposed

395

353

179

Ewes Lambing

354

324

164

Lambs Born

575

453

187

Lambs Weaned

450

341

167

Lambs Weaned/

Ewe Exposed

1.14

.97

.93

Table 11. Merged systems and lambing time to compare breeds. The HI control group data is not incorporated in any of the merged data sets.

BREEDS

MXR

RXR

Ewes Exposed

465

462

Ewes Lambing

425

417

Lambs Born

570

635

Lambs Weaned

469

495

Lambs Weaned/

Ewe Exposed

1.01

1.07

summary

Environmentally the need is to control leafy spurge with reduced reliance on herbicide exists. This research is needed to preserve the role of the sheep industry in North Dakota agriculture and to improve the economic viability of impacted beef producers.

References

Leistritz, F.L., D.E. Bangsrud and J.A. Leith. 1994. Economic Impact of Leafy Spurge in North Dakota. Leafy Spurge News Vol XVI Issue 1.

National Agricultural Statistics Service 1993. Sheep and Lamb Inventory. USDA, Washington, D.C.

Nudell, D.J., Where Will My Business Records Take Me. 35th Annual Western Dakota Sheep Day Progress Report.