Chapter 8: Considerations Concerning Stocking rate

Transcription

1 Chapter 8: Considerations Concerning Stocking rate 1. The concept of grazing capacity. 2. What we have learned from stocking rate studies. 3. Grazing intensity versus grazing timing. 4. Components of stocking rate. a. Distance from water and slope b. Forage demand by grazing animals c. The harvest coefficient d. Stocking rate calculation 5. Benefits of conservative stocking. 6. Stocking rate economics.

2 Cornerstones of Grazing Management 1. Proper stocking rate 2. Proper distribution 3. Proper kinds of animals 4. Proper grazing system ***Proper stocking rate is most important

3 Conservative versus Heavy stocking st Qtr 2nd Qtr 3rd Qtr 4th Qtr East West North st Qtr 2nd Qtr 3rd Qtr 4th Qtr East West North

4 Stocking vs. Specialized grazing systems Range research shows stocking rate has had a much bigger impact on range vegetation and financial returns than specialized grazing systems. Specialized grazing systems will not overcome the impacts of excessive stocking.

5 Stocking rate vs season of use Stocking rate has had much more effect on rangeland vegetation than season of use

6 Table 20. Effects of grazing management on semi-desert grass-shrub rangeland in southeastern Arizona. Continuous Summer Winter Characteristics yearlong grazing grazing grazing Duration of study Annual precipitation (in) % Grazing use Forage production (lb/ac) Perennial grass prod. (lb/ ac) Calf weight (lbs) Range Trend up stable-down stable-down

7 Table 20b. Perennial grass yields and cover showed the greatest increases where percent use was lowest. Both vegetation and cattle performances was higher under year-long than seasonal grazing. The authors recommended that grazing use on the perennial grasses not exceed 40%. Stocking these ranges for about 35% use of forage with some destocking in dry years was considered the best strategy. Source: Martin, S.C. 1975; Martin, S.C. and D.R. Cable, 1974.

8 Definitions of some grazing terms Heavy grazing- a degree of herbage utilization that does not permit desirable forage species to maintain themselves. Moderate grazing- a degree of herbage utilization that allows palatable species to maintain themselves. Light grazing a degree of herbage utilization that allows palatable species to maximize their herbage producing ability.

9 Definitions continued Conservative grazing a degree of herbage utilization between light and moderate, generally involving about 35% use of forage. Severe grazing a degree of herbage utilization generally above 60% use of forage that results in long term damage to the range.

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12 Stocking Rate and Forage Production Heavy stocking has greatest effects on forage production in drought years.

13 Table 12. Forage Production (lbs/acre) on Heavily and Moderately Stocked Pastures in Drought Compared to 10-years Average on the Fort Stanton Experimental Range in New Mexico. Drought 10 years Drought year Years Average as percent Grazing intensity 1974 ( ) of average Heavy (50-55% use) % Moderate (40-45% use) % Source: Pieper et al. 1991, Holechek, 1994.

14 Table 13. Forage Production (lbs/acre) on Moderately and Conservatively Stocked Pastures in Drought Compared to 6-years average on the Chihuahuan Desert Rangeland Research Center. Drought 6 year Drought year years Average as percent Grazing intensity 1994 & of Average Moderate (40-45% use) % Conservative (30-35% use) % Source Molinar 1999, Molinar et al, 2002.

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17 Table 6. Influences of grazing intensity on cattle production (yearlings) on ponderosa pine bunchgrass in Colorado 1 Heavy Study duration years Length of grazing months Period of grazing Jun-Oct Jun-Oct Jun-Oct Acres/ yearling % use of forage Forage prod (lb/ ac) 1,256 1,565 2,037 Gain/ head (lbs) Net return ($ ac) Source Johnson W.M. 1953, USDA. Circ. 929 Moderate Light

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26 Stocking vs. Specialized grazing systems Range research shows stocking rate has had a much bigger impact on range vegetation and financial returns than specialized grazing systems. Specialized grazing systems will not overcome the impacts of excessive stocking.

27 Grazing capacity and stocking rate Grazing capacity - maximum animal numbers which can graze each year on a given area of range, for a specific number of days without inducing a downward trend in range condition. It is based on vegetation weight, not cover. Stocking rate the actual number of animals assigned to a rangeland unit for a given time period.

28 Components of weight estimate-key area grazing capacity (Holechek 1988) 1. Land area determination 2. Adjustment for ungrazable range 3. Determination of forage production 4. Selection of utilization Coefficient 5. Determination of forage demand by livestock and game animals 6. Adjustment for distance form water 7. Adjustment for slope 8. Computation of grazing capacity 9. Interpretation of grazing capacity relative to recent precipitation 10. Use of stubble heights to cross-check actual use.

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33 Stocking ranges How many days? How many animals? 500 lbs forage per acre (dry) 200 acres 100,000 lbs total 100,000 lbs X 0.35 (harvest coefficient)=35,000 lbs grazable forage 325 lbs forage per acre needed to protect the site 200 acres 65, 000 lbs forage that must be left on the site for protection 100, = 35, 000 lbs (can be consumed)

34 Stocking ranges cont. You have the following animals 10 cows (average weight = 800 lbs) = 8000 lbs 1 bull ( average weight = 1100 lbs) = 1,100 lbs 9 calves ( average weight = 200 lbs) = 1,800 lbs 10, 900 lbs

35 Stocking ranges cont. Ruminant animal will eat 2% of body weight/day (ranges from 2.6 on high quality forage to 1.4 on mature forage) 10, 900 x.02 = 218 lbs. forage consumed/day 35,000/218 = 160 days of grazing, however this is only a guideline.

36 Uses of grazing capacity information 1. Forage allocation to livestock and wildlife. 2. Quantification of forage resources on a pasture, ranch, or allotment. 3. Assignment of stocking rate when data are lacking on trend and grazing intensity. 4. Assignment of stocking rate when data are lacking or uncertain on past stocking rates.

37 Uses of grazing capacity information cont. 5. Determines ranch monetary value. * Grazing capacity is the most expensive of the 4 types of grazing surveys (trend, intensity, capacity, condition). ** Sound grazing capacity data requires at least 3 years of data collection.

38 Problems with stocking at grazing capacity 1. Major reductions in livestock numbers will be needed in one half the years to avoid rangeland degradation. 2. Difficulty in accurately estimating forage crops. 3. Stocking at capacity generally does not permit rangeland improvement. 4. Stocking at capacity gives lower financial returns than conservative stocking ( 80-90% of capacity)

39 Problems with stocking at grazing capacity cont. 5. Severe financial losses can occur under drought conditions. 6. Multiple use values are difficult to maintain. * Stocking at capacity involves about 40% use forage on New Mexico rangelands. ** Considerable research shows the financially most effective stocking rate is well below what the rangeland vegetation will sustain.

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42 Table 6. Influences of grazing intensity on cattle production (yearlings) on ponderosa pine bunchgrass in Colorado 1 Heavy Study duration years Length of grazing months Period of grazing Jun-Oct Jun-Oct Jun-Oct Acres/ yearling % use of forage Forage prod (lb/ ac) 1,256 1,565 2,037 Gain/ head (lbs) Net return ($ ac) Source Johnson W.M. 1953, USDA. Circ. 929 Moderate Light

43 Table 8. Yearling cattle production and financial return characteristics at the Central Great Plains Experimental Range, Colorado Grazing Intensity Excessive Moderate Forage production (lbs/acre) Forage utilization (%) Weight again per animal (lbs) Weight again per unit area (lbs/acre) Death loss (%) Gross income/acre ($) Gross income/yearling ($) Source; Kipple, G.E., and D.F. Costello. (1960). Vegetation and cattle to different intensities of grazing on shortgrass range of the central Great Plains. U.S. Dept. Agric. Tech. Bull

44 Stocking plans recommended for New Mexico and other western rangelands. 1. Stock for about 30% use of long term average forage production. 2. Apply flexible stocking in drought. 3. In dry years sell older cows 4. Always sell livestock to level forage resources will support; avoid expensive feeding programs. 5. Rest or lightly graze for 2 growing seasons after severe drought. 6. Restock with about one half normal herd first year after severe drought.

45 Benefits of conservative grazing (30-35% use of forage) 1. Maximized long term (and often short term) financial returns from ranching 2. Permits improvement in forage productivity. 3. Reduces risk of damage to range from heavy grazing in drought. 4. Facilitates multiple use concept on public lands. 5. Strongly and broadly recommended by researchers conducting long term razing studies.

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47 Guidelines to proper use Heavy use- Range has a clipped or mowed appearance. Over half of the fair and poor forage-value plants are used. All accessible parts of the range show use, and key areas are closely cropped. They may appear stripped if grazing is severe. There is evidence of livestock trailing to forage. Moderate use (proper use)- About one-half of the good and fair forage value plants are used. There is little evidence of livestock trailing. Most of the accessible range shows some use.

48 Guidelines to proper use cont. Light use- Only choice plants and areas are used. There is no use of poor forage plants. The range appears practically undisturbed. On key areas average stubble heights of 12 to 14 inches for tall grasses, 6 to 8 inches for mid grasses and 2 to 3 inches for short grasses are recommended minimums for proper use.

49 Guidelines on management changes If grazing intensity is heavy on 30% or more of a pasture two years in a row or in 2 years out of 5 management changes are need If grazing intensity becomes severe on one third or more of the pasture in any year, management changes should be implemented

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