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Grazing Management

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Stocking Rates

Animal Forage Requirements

Average Forage Production

Example of Determining Stocking Rates

Grazing Systems

Additional Information

 

Stocking Rates1

 

Livestock

How many animals per acre for your pasture are too many? The first step in making this determination is calculating what the grazing animal’s daily forage needs are and then comparing that needed amount to the daily amount of forage produced in the pasture. The end product of this calculation can be referred to as the pasture’s Stocking Rate. The following information provides guidelines for understanding and figuring out Stocking Rates. For specific information on your particular situation, contact your local NRCS or Extension office.

Animal Forage Requirements2

Forage consumption is affected by many factors and varies with individual animals. Factors include forage quality, age of animal, topography, breed type and health condition to name a few. The average daily forage intake for most animals is 2.6% of their body weight per day. Remember this figure can vary from 1.5% to 3.5%. For ease, the calculations listed in Table 1 for daily, monthly and yearly forage requirements are based on 2.6% of body weight.

Table 1

Animal Class

Pounds of Dry Forage*

 

Consumed Per

 

Day

Month

Year

Cow with calf:

26

790

9,490

1 yr. Old Cattle:

15.6

474

5,694

Mature Horse:

32.5

988

11,862

Mature Sheep:

5.2

158

1,898

Mature Goat:

3.9

118

1,423

*The above listed numbers reflect forage weight on an oven dried basis, and do not account the amount of forage lost per day due to trampling.

The second part of the stocking rate equation is determining how much forage a pasture can supply.

Average Forage Production3

The amount of forage produced per acre will vary significantly from one site to another. These variations are the result of climate, soil, type of forage, available moisture and degree of management. Here on the Front Range of Colorado, it is typical to find forage production levels between 200 to 2,000 pounds annually per acre in dryland pastures. Irrigated pastures will produce from 2,000 to 10,000 per acre. Please refer to the chart below for a listing of typical, Annual Useable Production levels.

Table 2

Type of Pasture

Average Annual

Useable Pounds of

Forage Per Acre Per Year*

Dryland Crested wheat Pasture

450

Dryland Pubescent/

Intermediate wheat Pasture

700

Irrigated Smooth brome Pasture

3,000

Dryland Native Pasture on Clayey Soils

375

Dryland Native Pasture on Deep Sand Soils

750

Dryland Native Pasture on Loamy Soils

375

Dryland Native Pasture on Wet- Meadow Sites

1,625

Dryland Native Pasture on Salt Flat Sites

375

*The Annual Useable Yield as listed above is based on the production level of typical rangeland found in the Eastern Front Range of Colorado in fair to good ecological condition under normal annual precipitation.

The amounts listed in the Average Annual Useable Yield column are 50% of the actual estimated forage produced per year. This is in keeping with a rule of thumb called the "take half, leave half" method. It is thought that if only half of a plant’s annual growth is consumed, the remaining one half of the above ground portion of the plant is sufficient to collect sunlight and nutrients to carry it over to the next growing season in a healthy, reproductive state.

Example of Determining Stocking Rates

Table 3 contains an example of determining the Stocking Rate on 10 acres of Dryland Native Pasture on Loamy Soils. One cow & calf, two horses and one sheep are used in this example.

Table 3

How Much Forage is Needed?

 
Total amount of forage needed per month (based on figures in Table1):
 
Cow & Calf
 
2 Horses
 
Sheep
 
790
 
1,976
 
158
 
2,924
Pounds Total

How Much Forage Do We Have?

Total Forage Produced Per Year:
Acres
Pounds of Useable Forage
Per Acre Per Year
(based on figures in Table 2)
10
375
3,750
Pounds Total
Total Forage Produced Per Month:
Total Pounds
of Forage Produced
Per Year
Months
Per Year
12
3,750
312.5
Pounds Per Month

How Long Can This Pasture Support Our Cow & Calf,

Two Horses, and One Sheep?

Total Forage Available Per Month/Needed forage per month
312/2,924=0.1 month / or 72 hours / or 3 days per month/ or 36 days per year.

 

The Example in Table 3 shows that this pasture can support these animals only 36 days out of every year. However, these animals need to eat every day of the year. Now what? Now it’s time to set up your grazing system!

Grazing Systems

Continuing with the example given above let's work through a couple of optional grazing systems.

Yearlong Grazing

Year long grazing implies that the animals will be left in one pasture all year long. However, in this situation there is not enough forage to sustain those animals all year. So, we must do a few modifications. This pasture should be used only as a "turn-out" area that will supply a small fraction of the total forage needs for these animals. The balance of the feed requirements should be derived from another source such as hay or hay and grain.

So, let’s say that the animals will graze the pasture for 2 hours a day, 365 days per year. How will the animals’ nutritional needs be met? Let’s look at Tables 4 & 5.

Table 4

Pounds of Forage Derived from the Pasture Per Day:
Time of Use
Hours per Day
2
Hours per Year
712
Days per Year
30
Days of Use * Forage Needs per Day (Table 1): 30*(26+32.5+32.5+5.2)=2,886 pounds of forage derived from the pasture every year.
2,886/365 Days per year=7.9 total pounds of forage taken from the pasture per day.
       

Table 5

Average Pounds of Forage Consumed by Each Class of Animal Based on Weight
 
Cow & Calf
Horses
Sheep
% of Forage
Consumed from
Pasture Per Day
27%
70%
3%
% Converted to
Pounds
2.1
5.5
0.3
Difference Between Daily Forage Needs and Pounds of Forage from Pasture
 
26-2.1=
65-5.5=
5.2-0.3=
Additional Pounds Needed
23.9
59.5
4.9
Rotational Grazing

There are several types of rotational grazing systems. These systems have certain advantages over yearlong grazing. For this example we will work with a simple two-pasture rotational system. For ease of management, it is better to try and make the pastures equal in size if their production levels are equal.

Using the above example of a 10-acre lot of land, we now split the pasture into two 5-acre pastures with cross fencing. In order to achieve the benefits of rotational grazing, one pasture should be grazed while the other is in a state of rest. Important things happen while a pasture is being rested, including leaf growth, root growth, and plant reproduction. All of these functions are necessary to maintain a healthy, vigorous stand of grass that is weed-free.

Another benefit of the rest period in irrigated pastures is a reduction in soil compaction. Rest irrigated pastures during and after irrigation until the top several inches of the soil are dry. Soil compaction can also occur if animals are left in the pasture during and after major storm events. Soil becomes compacted when it is inundated with water and heavy traffic or trampling at the same time. This compaction reduces or eliminates the soil’s structure, which has natural channels that carry nutrients, water and air to the root systems of plants.

If a pasture does not have a sufficient rest period, the effects of overgrazing eventually take place. Overgrazing happens when animals are left in one place too long, continually eating the plant re-growth, and not allowing the plant to regain the material lost to grazing. Grasses then become weak which allows weeds to establish in pasture areas.

Therefore, judging the proper amount of rest needed in a rotational grazing system is crucial for a successful, sustainable grazing system. So how do you know when rest is needed?

Judging the Grass for Sufficient Rest 4

Table 6 lists minimum stubble heights for a few of our common types of grasses.

Table 6

Forage:
Minimum Stubble Height
(inches):
Crested wheatgrass on most soil types
2
Western wheatgrass on clay or loam soil types
3
Tall wheatgrass, on wet meadow sites
6
Switchgrass on sandy soils
6
Little bluestem, on loamy soils
4
Sideoats grama, on loamy soils
3
Blue grama, on loamy/clayey soils
2
Smooth brome, on most soils
3

 

These minimum stubble heights are what should be standing on the ground when animals are moved out of an area. The pasture area will probably never have that "just mowed" look where all plants are equal in height. But the majority of the plants in a given area should be at or above the recommended height. The area should then be rested until at least double the amount of stubble listed is present. Depending on the season, precipitation, climate and the type of forage present, the rest period can be anywhere between 15 days (with irrigation), and 90 days, if in a drought year with no irrigation water. The key to a successful rotation system is observation.

Complex Rotational Systems

As stated earlier, rotational grazing systems with more pastures containing fewer acres are more complex and productive if used properly. The productivity increase initially is really an increase in harvest efficiency. For instance, if the 10-acre pasture in the above example is split into two five acre pastures with cross fencing, the 1 cow, 2 horses and 1 sheep are forced to compete for the available forage more than they did in the 10-acre pasture. The result is that the animals move away from their comfort zone areas like the barn and water tank, to areas at the edges of the pasture. Plants are thereby grazed, that previously may not have been used.

Complex rotational grazing systems involve pastures that are subdivided into 3 or more cells.

These systems take time to manage and an educated eye. For pointers on how to apply your grazing system please contact your local Extension Service or NRCS office.

Additional Information

1Natural Resources Conservation for Small Acreage Land Users Brochure, Southeast Weld Soil Conservation District, 1996, 303-659-7004

2 USDA, Natural Resources Conservation Service, Grazing Lands Technology Institute, National Range and Pasture Handbook, September 1997.

3 USDA, Natural Resources Conservation Service, Technical Guide, Section II-E, Various Colorado Range Site Descriptions, 1980 to 1989.

4 USDA, Natural Resources Conservation Service, Technical Guide, Section IV, Standards and Specifications, Pasture and Hayland Management, Colorado, April 1985.

Brighton NRCS Field Office, 303-659-7004

C.A.R.T - A Manual for Success, 2nd Edition

Complete information on this and many other Small Acreage topics are now available in

C.A.R.T - A Manual for Success, 2nd Edition

CART manual
To obtain a copy of this book please contact the Adams County Small Acreage Coordinator 303.637.8157

 

 

 

 

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