How to Determine How Many Cattle Can Be Grazed on a Pasture
Determine the amount of land you have available., Calculate the estimated stocking rate for your area., Determine how long you want the cattle to be on the land., Determine the number of animal units that can graze on your piece of land., Adjust for...
Step-by-Step Guide
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Step 1: Determine the amount of land you have available.
This will be the first of one of the most important pieces of information you need in order to find how many cattle you can graze.
This number can be in acres or hectares.
For example, you may have a quarter section (equivalent to 160 acres) available for grazing.
You can even work with as little as one acre.
As long as you stick with one unit of measure (acres versus hectares), you are able to work with as much or as little land as you wish. -
Step 2: Calculate the estimated stocking rate for your area.
The stocking rate for your location is determined by the amount of forage you have in terms of pounds per acre or kilograms per hectare, the utilization rate expected by the animals based on pasture condition, and how much of that forage is utilized by a standard animal unit for one month.
The amount of forage you have in your pastures can be eye-balled, though if you have not learned how to properly eye-ball how much forage you have, you can be far more in accurate than if you clipped various samples around the pasture, and weighed then after they are dried down.
To get an accurate clipping measurement, you need to use a 1 ft by 1 ft quadrat (square) so that you can calculate the amount of forage (in pounds) per acre (where 1 acre = 43,560 square feet) after its dry matter weight has been assessed.
Utilization rate is a percentage of how much a cow should remove compared with the total amount of forage that is actually there.
For most pastures that are in decent condition (with 6 to 8 inches of forage or more) the utilization rate should not exceed 55%.
Poorer pastures with low amounts of herbage should have a utilization rate of less than 30%.
Excellent pastures can have a high utilization rate only if the animals are in there for a short amount of time; otherwise it is best to stick with a 50 to 55% utilization rate to ensure plenty of plant material is left behind.
One AU is estimated to consume between 600 to 900 lb of forage in one month.
To make things simpler, and as an average used by all stockmen to calculate their stocking rate for their land, the best estimate is that one animal unit will consume 800 pounds of forage in one month.
This is what makes an Animal Unit Month (AUM).
To calculate out stocking rate, let's assume your pastures are producing 1600 pounds of forage per acre.
With a 50% utilization rate, and assuming one AUM consumes 800 pounds of forage a month, that will give you a stocking rate of
1.0 AUM/acre.
The formula is:
Stocking Rate = (Forage production x )/800 lb/month Per our example:
Stocking rate = (1600 lb/acre x (50%/100))/800 lb/month =
1.0 AUM/acre , Typically this is measured by months, not days.
For most North American areas (not including the tropics) a typical grazing season is between 4 to 6 months.
More southern grassland areas, like in California and down into Florida and Texas, are more flexible with being able to graze for 12 months a year.
Thus, let's assume you live an area where you are only wanting to graze these 100 cows (see step 1 above) for 4 months.
Only use days if you are splitting up the pasture into multiple paddocks to rotationally graze your cattle in.
You can use days for this formulation.
Since most of these calculations are used by months, to determine days, divide by
30.5 (because not all months of the year have 30 days). , As mentioned in step 2 above, one animal unit is equal to one 1000 lb cow-calf pair.
Thus, the resulting number will be in terms of those animals and not the actual average size of the cows to be grazed on your piece of land.
The formula for determining number of animal units is (Pasture size x Stocking rate ) / Time to graze (months) Therefore, as per our example, Number of Animal Units = (160 acres x
1.0 AUM/acre) / 4 months = 40 AUs , Most modern cows are not 1000 lb, but rather 1400 lb.
If we use 1400 lb cows, then to adjust for animal unit equivalencies by weight, we simply divide the actual average weight of the cows by the weight of the standard animal unit, like so: 1400 lb / 1000 lb =
1.4 AUE., Taking the number of animal units calculated from step 4, which was 40 AUs, divide by the AUE calculated in step 5, to get
28.57 AUEs on 160 acres for 4 months.
To calculate, incorporating step 5:
Animal Unit Equivalents = Number of AUs / (Actual animal weight / Animal unit weight); thus AUEs = 40 AUs / (1400 lb / 1000 lb) =
28.57.
In other words, you can have around 29 cows (weighing an average of 1400 lbs) graze your 160-acre parcel of land for four months. , Monitor pasture conditions and the grazing behaviour of the cows.
If they are not getting enough (as in, they do not have their heads down most of the time grazing, but moving around excessively), then it may be time to pull them out and move them to another area to allow the pasture to rest.
It's important to understand that these calculations are merely a guide and an estimation.
They are not exact, nor ever will be.
It's up to you, as manager, to pay attention to the resource (forage) the cows need in order to both keep your cows happy, and not cause significant damage to the land. -
Step 3: Determine how long you want the cattle to be on the land.
-
Step 4: Determine the number of animal units that can graze on your piece of land.
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Step 5: Adjust for actual weight of the cows to be grazing the piece of land.
-
Step 6: Determine the number of animal unit equivalents to graze your land.
-
Step 7: Put the cows out to the pasture to allow them to graze.
Detailed Guide
This will be the first of one of the most important pieces of information you need in order to find how many cattle you can graze.
This number can be in acres or hectares.
For example, you may have a quarter section (equivalent to 160 acres) available for grazing.
You can even work with as little as one acre.
As long as you stick with one unit of measure (acres versus hectares), you are able to work with as much or as little land as you wish.
The stocking rate for your location is determined by the amount of forage you have in terms of pounds per acre or kilograms per hectare, the utilization rate expected by the animals based on pasture condition, and how much of that forage is utilized by a standard animal unit for one month.
The amount of forage you have in your pastures can be eye-balled, though if you have not learned how to properly eye-ball how much forage you have, you can be far more in accurate than if you clipped various samples around the pasture, and weighed then after they are dried down.
To get an accurate clipping measurement, you need to use a 1 ft by 1 ft quadrat (square) so that you can calculate the amount of forage (in pounds) per acre (where 1 acre = 43,560 square feet) after its dry matter weight has been assessed.
Utilization rate is a percentage of how much a cow should remove compared with the total amount of forage that is actually there.
For most pastures that are in decent condition (with 6 to 8 inches of forage or more) the utilization rate should not exceed 55%.
Poorer pastures with low amounts of herbage should have a utilization rate of less than 30%.
Excellent pastures can have a high utilization rate only if the animals are in there for a short amount of time; otherwise it is best to stick with a 50 to 55% utilization rate to ensure plenty of plant material is left behind.
One AU is estimated to consume between 600 to 900 lb of forage in one month.
To make things simpler, and as an average used by all stockmen to calculate their stocking rate for their land, the best estimate is that one animal unit will consume 800 pounds of forage in one month.
This is what makes an Animal Unit Month (AUM).
To calculate out stocking rate, let's assume your pastures are producing 1600 pounds of forage per acre.
With a 50% utilization rate, and assuming one AUM consumes 800 pounds of forage a month, that will give you a stocking rate of
1.0 AUM/acre.
The formula is:
Stocking Rate = (Forage production x )/800 lb/month Per our example:
Stocking rate = (1600 lb/acre x (50%/100))/800 lb/month =
1.0 AUM/acre , Typically this is measured by months, not days.
For most North American areas (not including the tropics) a typical grazing season is between 4 to 6 months.
More southern grassland areas, like in California and down into Florida and Texas, are more flexible with being able to graze for 12 months a year.
Thus, let's assume you live an area where you are only wanting to graze these 100 cows (see step 1 above) for 4 months.
Only use days if you are splitting up the pasture into multiple paddocks to rotationally graze your cattle in.
You can use days for this formulation.
Since most of these calculations are used by months, to determine days, divide by
30.5 (because not all months of the year have 30 days). , As mentioned in step 2 above, one animal unit is equal to one 1000 lb cow-calf pair.
Thus, the resulting number will be in terms of those animals and not the actual average size of the cows to be grazed on your piece of land.
The formula for determining number of animal units is (Pasture size x Stocking rate ) / Time to graze (months) Therefore, as per our example, Number of Animal Units = (160 acres x
1.0 AUM/acre) / 4 months = 40 AUs , Most modern cows are not 1000 lb, but rather 1400 lb.
If we use 1400 lb cows, then to adjust for animal unit equivalencies by weight, we simply divide the actual average weight of the cows by the weight of the standard animal unit, like so: 1400 lb / 1000 lb =
1.4 AUE., Taking the number of animal units calculated from step 4, which was 40 AUs, divide by the AUE calculated in step 5, to get
28.57 AUEs on 160 acres for 4 months.
To calculate, incorporating step 5:
Animal Unit Equivalents = Number of AUs / (Actual animal weight / Animal unit weight); thus AUEs = 40 AUs / (1400 lb / 1000 lb) =
28.57.
In other words, you can have around 29 cows (weighing an average of 1400 lbs) graze your 160-acre parcel of land for four months. , Monitor pasture conditions and the grazing behaviour of the cows.
If they are not getting enough (as in, they do not have their heads down most of the time grazing, but moving around excessively), then it may be time to pull them out and move them to another area to allow the pasture to rest.
It's important to understand that these calculations are merely a guide and an estimation.
They are not exact, nor ever will be.
It's up to you, as manager, to pay attention to the resource (forage) the cows need in order to both keep your cows happy, and not cause significant damage to the land.
About the Author
Cynthia Allen
Professional writer focused on creating easy-to-follow hobbies tutorials.
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