Grazing Intensity Research On Coteau Rangelands


Alternative Forage Sampling Methods

The forage production samples are used to calibrate and test the swardstick and radiometer, two alternative methodologies for sampling forage production.

Remote Sensing

Forage production from known locations will be compared with reflectance values on infrared and regular color aerial photos. The photos can be scanned into a computer and analyzed to develop a map and comprehensive inventory of the entire forage base.

Forage Quality

The forage samples were analyzed each year until 1999 for nutritional quality to determine if, over time, different intensities of grazing result in plant communities which produce forage of different quality. Table 9 shows the average nutritional quality of grasses and forbs on each treatment from 1989 to 1998. Although differences in nutritional quality have developed between the grazing treatments, the reasons for the differences are not clear. On silty range sites the grasses have higher crude protein and digestibility and lower fiber components at the higher grazing intensities. On the heavily grazed treatments the grass that is available for grazing is mostly regrowth which is of higher quality. However on overflow sites both grasses and forbs are highest in fiber components on the heavy grazing treatment. Perhaps on these sites cattle are selecting species of higher quality and leaving those that are higher in fiber. On silty sites forbs are highest in neutral detergent fiber on the ungrazed and extreme grazing treatments. As the ungrazed forage matures on the ungrazed treatment it becomes higher in fiber. On the heavily grazed treatments only forbs of lower quality would remain ungrazed. These differences in nutritional quality have occurred gradually over the course of the study.

Table 9. Average nutritional quality of forage on the grazing intensity trial 1989-1998.

Treatment Crude Protein (%) In Vitro Dry Matter Digestibility (%) Acid Detergent
Lignin (%)
Acid Detergent
Fiber (%)
Neutral Detergent
Fiber (%)

Overflow sites--forbs

None

Light

Moderate

Heavy

Extreme

9.17 c1

8.80 c

9.13 c

10.42 a

9.87 b

61.86

60.53

61.74

59.99

60.14

6.80 c

7.52 ab

7.31 abc

7.81 a

7.23 bc

35.98

38.08

37.67

37.19

36.82

43.06 b

44.85 ab

44.79 ab

46.40 a

44.64 ab

Overflow sites--grasses

None

Light

Moderate

Heavy

Extreme

6.57 d

7.03 bc

6.73 cd

7.29 ab

7.57 a

50.65

51.38

50.63

49.91

52.12

4.67

4.42

4.58

4.61

4.57

42.56 b

42.80 ab

43.02 ab

43.85 a

41.01 c

67.03 c

67.69 bc

68.46 ab

69.37 a

68.85 ab

Silty sites-forbs

None

Light

Moderate

Heavy

Extreme

10.40

10.75

10.88

10.79

10.76

59.22 b

61.94 a

60.48 ab

60.33 ab

62.00 a

7.80

7.35

7.41

7.73

7.31

36.58 a

36.15 ab

34.43 c

34.97 bc

33.86 c

50.01 a

45.40 b

44.85 b

45.42 b

48.70 a

Silty sites-grasses

None

Light

Moderate

Heavy

Extreme

7.35 c

7.36 c

7.88 b

8.40 a

8.55 a

49.11 c

46.68 d

50.55 bc

51.14 b

55.86 a

4.17 b

4.64 a

4.19 b

4.24 b

4.04 b

42.84 ab

43.64 a

42.32 b

40.83 c

39.31 d

69.44 bc

72.05 a

71.43 ab

71.48 ab

68.37 c

1Means in the same column followed by the same letter, or no letter, are not significantly different at P=0.05.

 



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