If you’re attempting to create a successful livestock production system, then one important element is maintaining detailed records on your stock rate.
Stock rate is the number of animals on a given amount of land over a certain period of time.
Use this metric to understand and estimate forage requirements as you run your land.
Here’s all you should know.
1. What is the stock rate?
The stock rate is the number of animal units per acre for a specific amount of time.
By using the stock rate as well as the animal performance and precipitation records, you can identify the optimal levels of stock on your property.
Recognizing and maintaining the proper stocking rate for a forage resource is the starting point for keeping a sustainable pasture.
This is because a given acre will only produce a certain amount of forage and support a certain number of livestock.
2. What other factors can stock rate affect?
The stock rate can impact the following factors:
Owner’s and operator’s management goals
Animal species (cattle, sheep, horses, etc.) as well as performance
Class of livestock (dry cow, lactating cow, bull, steer, etc.)
Acres available for the grazing season
The health of grassland resources (ex: infiltration rates, species composition, annual production)
Livestock water (quantity, quality, and distribution)
Forage species composition
Forage quality and palatability
Management practices (prescribed grazing systems, animal densities, cross-fencing, etc.)
3. How do you calculate the stock rate?
Here is the formula for the stock rate:
Total Land Area / [Number of Animal Units x Grazing Season]
Keep in mind that cattle and other grazing animals are not the same physical size.
Thus, you’ll need to convert them to animal units.
The term animal unit equivalent (AUE) allows you to estimate the potential forage demand for different types of animals or cattle that weigh more/less than 1,000 pounds.
AUE is based on a percentage (give or take) of the standard animal unit.
It also considers the physiological differences between animals.
See Section 6 for more information.
4. What are some basic terms to know when discussing stock rates?
It’s useful to know the following definitions:
Animal unit (AU): any combination of animals with a forage demand of 26 pounds of dry matter per day (sometimes specifically refers to a lactating 1,000-pound cow with a calf)
Animal unit equivalent (AUE): developed to standardize grazing demand among different herbivore species
Available forage: the amount of herbaceous and/or woody material available for grazing
Carrying capacity: the maximum long-term stock rate that can be sustained without detrimental effects on the land resource
Forage demand: the amount of forage required to sustain a grazing animal over a specific period
Grazing pressure: the ratio of forage demand to the amount of available forage at a given point in time
Stock density: the number of animals per unit of area of land at a given point in time
Stock rate: the number of animals per unit area over a given period
5. What is an Animal Equivalent Unit?
Every animal species has an equivalency factor, which is some percentage of an AU.
This allows you to adjust for animal size and metabolism.
Here is a sample list from the USDA:
|Animal||Weight (lb.)||Animal Unit Equivalent (AUE)|
|Cow, with calf||1000||1.00|
|Cow, with calf||1200||1.15|
|Cow, with calf||1500||1.35|
|Sheep, with lamb||120||0.20|
6. How do you use AUE when calculating stock rates?
Great question! You must first calculate the number of animal units (AU) using the AUEs.
Here’s how you can do that.
Number of Heads x AUE = Total AUs
For example, 100 heads of horses x 1.25 AUE = 125 AU
To calculate the stock rate, you should multiply the total land area and then divide it by the AUs multiplied by the grazing season.
This will give you your stock rate.
So, if you have 100 acres total and your grazing season is 6 months long, then it would leave you with this:
100 / 125 x 6 = 0.13 acres per animal unit month
You can now compare your stock with the estimated AUM/acre carrying capacity of your soil and forage type.
For example here is a table of the estimated stocking rates in animal unit months per acre by soil type for each of South Dakota’s Major Land Resource Areas from North Dakota State University.
|Vegetation Type/Ecological Site||53A&B||54||55A&B||56||58 C&D|
|Very Shallow/Thin claypan||0.30||0.24||0.37||0.43||0.22|
|— Wet meadow||0.60||0.60||0.60||0.70||0.60|
7. What is the difference in the stock rate of introduced and rangeland forests?
The general concepts of determining the stock rate for these types of lands are similar.
However, there is one major difference: allowable use.
For the rangeland forest, the allowance use or percent utilization of available forage is lower.
Introduced forages can be utilized at a much higher degree if both moisture and fertility are readily available.
That said, do not mistake utilization for consumption.
Utilization includes decomposition, waste, and consumption by insects as well as other herbivores.
8. How does the stock rate affect livestock?
This is an interesting question because the general opinion has always been “more cattle equal more money.”
But this isn’t always the case.
In fact, the data has shown that the producers who have a more conservative stock rate have ended up with higher-quality animal production.
For example, the Galloways Plains grazing trial revealed that halving the stock rate allows individual animal weight to increase while only subtly impacting gross production.
In other words, halving the stock rate doesn’t half production.
While there are fewer animals, they thrive.
They grow faster.
If you reduce from an even higher stock rate, then this effect becomes distinctly more pronounced.
Although you might not expect it, heavier stock rates can maximize returns in the short term.
That said, the net return may not be quite so high if you don’t account for the capital tied up in the livestock and variable costs.
There are also some distinct disadvantages to pushing the stock rate like…
Lost ability to carry capacity
Direct loss of production
Higher maintenance costs (supplementation, weeds, etc.)
Rehabilitation costs (improving land)
9. What’s the difference between stock rate, carrying capacity, and stocking density?
Although these terms are often used interchangeably, they are not, in fact, the same, here are the differences in these terms and how you can use them correctly as you manage grazing on your land.
Stock rate – the relationship between the number of animals and the size of forage resource on which they are placed
Carrying capacity – the number of animals that a forage resource can support in the growing season (carrying capacity is dependent upon proper management as well as an acceptable level of production)
Stocking density – the number of animals or livestock on a part of the pasture for a certain portion of time (more commonly used when we think of short-term, intensive grazing management)
In other words, the carrying capacity is the maximum long-term stocking rate that can be sustained without there being detrimental effects on the land in question.
It’s part of the equation, but the two terms aren’t synonymous.
Additionally, while stock rate explains the relationship between livestock and the forage resource, stock density is just animal concentration on the land.
10. How can you be an effective manager?
Stock rates can be set appropriately when you’re mindful of numerous variables.
An effective land manager will balance all the factors named above.
Their priority will be forage production and animal performance, paying special attention to animal performance in the long run.
They can do this by implementing flexibility and contingency plans into their operations that account for changing weather conditions, natural disasters, and variations in the livestock markets.
A mindful manager can plan stock rates by keeping the following in mind.
Forage demand – how much forage is required by the type and class of animals grazing the range or pasture unit
Available forage – how much forage is produced during the year and how much is available for livestock consumption
Duration – how long the animals will use the area
11. What is a stock rate calculator?
Are you looking for an easy way to calculate your stock rate?
This Stock Rate Calculator will help you determine the number of sheep or cattle that you should put into a paddock based on its carrying capacity.
Get started at the link above.
When it comes to producing livestock effectively, it’s all about the stock rate.
If you improperly use the stock rate, then it can decrease the vigor of desirable forage species as well as animal performance.
If this occurs, then you’ll see an overall reduction in your land’s profitability and sustainability.
If you plan to use your land for animal production, the stock rate is an important factor that you cannot overlook.
Use the tips above to increase your production rate and keep things running efficiently.
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