Why Carrying Capacity Matters
Carrying capacity could be the most important concept in all of livestock agriculture. It is carrying capacity, specifically incorrect carrying capacity, also known as “overstocking”, that drives most of livestock agriculture’s environmental problems today.
Also commonly referred to as “stocking rate,” carrying capacity is the number of animals a parcel of land can support by providing adequate feed and retaining and recycling the nutrients they produce.
In grazing systems, where livestock harvest their own feed and spread their own manure, carrying capacity is foundational to a long grazing season that results in healthy animals, healthy pastures, and a healthy ecosystem.
A primary goal of every grazing operation should be to maximize the length of the grazing season. This is directly correlated to profit because grazed forages are the most inexpensive source of feed, and stored feeds are almost always the greatest expense. Management helps determine grazing season length.
The principles of managed grazing – the Three R’s of rotation, residual, and rest – drive pasture yield and quality and have a significant impact on the farmer’s ability to lengthen the grazing season. But the Three R’s only work when we get the carrying capacity right.
Carrying capacity is foundational to the success of livestock agriculture, balancing land stewardship with financial goals.
Determining what the land can support is not just an ethical responsibility, it’s the first step toward a synergistic relationship among the farmer, the livestock, and the land.
Farms that fail to determine carrying capacity correctly can be overstocked and run out of pasture before the end of the growing season or be understocked and grazing fewer livestock than the land could support, both resulting in reduced revenue.
Many factors influence carrying capacity. Some are inherent, such as soil type, topography, and climate. Others are choices, such as livestock class, management, and operational goals, like whether winter feed is produced on-farm or purchased off-farm.
Factors Influencing Carrying Capacity
The first step of determining carrying capacity is collecting information unique to the farming operation. The factors are broken into two groups: those that are more “foundational” to the particular type of livestock operation and are not likely to be changed, and “decision factors” that a farmer must determine from year to year.
Foundational Factors
Grazing Management
Frequency of rotation has a significant impact on pasture yield. The more often animals are moved, the higher the overall yield will be. For this calculation, a minimal three-day rotation is assumed.
Soil Type
Wisconsin is well-known for its diversity of soil types. Within a farm, and even within a pasture there can be multiple different soil types. Soil type strongly influences pasture yield. When calculating carrying capacity, the predominant soil type is most relevant. This information can be found at the Web Soil Survey.
Land Base
The total acreage used for determining carrying capacity should include any acres intended to be grazed during the grazing season. Any additional acres that are not used for livestock feed should not be included.
Forage Yield
Some farms with a history of growing crops on their land have a good idea of the average forage yield on their operation. Obtaining accurate yield estimates can be challenging. In the absence of accurate yield estimates, it is acceptable to utilize average forage yields for the region and soil type. This information is also at the Web Soil Survey, in the Soil Data Explorer under “Vegetative Productivity.”
It is very important to use dry matter yield per acre, and not wet or as-fed yields, because these are highly variable from differences in moisture content. Dry matter yield addresses these variations by correcting for moisture. Further, animal intake predictions, which will be covered later in this publication, are all based on intake of dry matter.
Figure 2. Pasture yield and carrying capacity for pastures established under various forms of grazing management. More frequent rotation leads to greater annual forage production (top) and less land required (bottom). Pasture yield data from UW-Madison (Chasen, 2023) and acreage requirement estimates from USDA-NRCS Forage Animal Balance Worksheet.
Animal Weight
Animal weight can vary drastically from farm to farm and even within a particular farm. To calculate carrying capacity, the average animal weight for the herd or flock is used. It is advisable to stay conservative (overestimate animal weight, underestimate yield) with this estimate, as it is more costly to overestimate than to underestimate carrying capacity.
This is especially important for growing animals. For example, calves continue growing through the grazing season and their weights are oftentimes underestimated. When planning carrying capacity, estimate end of grazing season weights for growing animals, such as calves. As with forages, many farms may not know the weights of their animals, but using standard values for different livestock classes is sufficient (for example, see Table 1).
Forage Intake and Allocation
Intake is a term that refers to how much feed or forage an animal consumes in a day. Allocation is the term used for the amount of feed or forage planned or set aside for an animal per day. In general, most livestock consume about 3% of their body weight in dry matter per day, and that value is used to estimate intake.
But calculating carrying capacity for year-round grazing systems must also account for material that is left behind via residual and trampling during the grazing season, as well as hay waste and increased consumption during cold weather. This is done by adding an extra 1% of dry matter to intake, so 4% of body weight is used to estimate forage allocation.
| Livestock Class | Average Weight | Allocation (lbs. dry matter per day) |
|---|---|---|
| Beef Bulls | 1500 | 60 |
| Beef Calves | 400 | 16 |
| Beef Cows | 1300 | 52 |
| Beef Stockers | 900 | 36 |
| Beef Yearlings | 800 | 32 |
| Dairy Heifers | 800 | 32 |
| Large Dairy Cows | 1500 | 60 |
| Small Dairy Cows | 1000 | 40 |
| Goats | 150 | 6 |
| Lambs | 75 | 3 |
| Sheep Ewes | 150 | 6 |
| Rams | 200 | 8 |
Decision Factors
Length of Grazing Season
The goals of each farm will vary, but most grazing operations interested in maximizing the grazing season have a goal of at least 180 days (6 months) of grazing. The irony of this value is that it is directly influenced by the farm’s actual carrying capacity.
Stockpile Grazing
Stockpile grazing is one tool that can extend the grazing season and reduce costs by delaying the need for stored feed. If a farm does not stockpile graze, this section can be ignored. Farms that do practice stockpiling need to start by identifying the target number of days they hope to stockpile graze. The number of grazing days will help to determine the length of stockpiling period and acres needed. A minimum of 30 days is recommended, but additional days can ensure more stockpiled forage. Forage growth rates slow as the season progresses and the stockpiling period exceeds 30 days. Thus, stockpiling pastures beyond 60 days is not likely to provide significantly more forage.
Stored-Feeding Season Length
No one can determine how long winter will be, but every farmer must estimate the number of days needed to feed livestock. Many grazing operations “outwinter,” or feed on pasture through the winter. One of the most common methods of feeding hay through the winter is bale grazing (see the Extension publication: Bale Grazing: A Winter Feeding Strategy).
For calculating carrying capacity, the duration of the stored-feed season will be the number of days remaining after the sum of grazing and stockpile grazing days are subtracted from 365 days. Many grazing farms with goals of 6 months of grazing and 2 months of stockpile grazing plan for 245 total grazing days and 120 days of stored feed.
For more information on how to implement stockpile grazing and bale grazing, refer to Bale Grazing: A Winter Feeding Strategy and Stockpile Grazing: A Strategy for Extending the Grazing Season, available on Wisconsin’s Grazing Roots resource library.
Calculating Pasture Carrying Capacity
When it comes to putting these numbers to work, calculating carrying capacity is a step-by-step process involving multiple interconnected factors. For example, a farm custom-raising dairy heifers for the summer will have a much greater carrying capacity than a farm raising beef cows and calves because they need not account for acres for hay production.
On the other hand, some farms employing winter-feeding may choose to purchase all hay to increase carrying capacity. These examples demonstrate how each step provides an opportunity for farmers to consider their options. Financial components of these decisions are not addressed here but must be part of the process. For example, some farms may consider alternatives to stockpile grazing for extending the grazing season such as annual cover crops, crop residues, etc.
To begin calculating carrying capacity, identify the necessary farm information in Table 2.
Soil type and forage production estimates for farms can be found in Web Soil Survey. Forage estimates are found in the Suitabilities and Limitations for Use tab > Vegetative Productivity section > Yields of Irrigated/Non-Irrigated Crops.
| Carrying Capacity Calculation Variable | Your Farm |
|---|---|
| Predominant Soil Type Use Web Soil Survey | |
| Land Base for Grazing (acres) | |
| Average Forage Dry Matter (pounds per acre) | |
| Average Animal Weight (pounds) | |
| Grazing Season Length (days) | |
| Stockpile Grazing Length (days) | |
| Stored-Feeding Length (days) | |
| Forage Dry Matter Accumulation (pounds per acre per day) |
Once the farm information is collected, calculating carrying capacity is a step-by-step process. Each step determines a different factor that helps the farmer consider operational options and decisions. The following factors are determined in the process laid out below. The calculations start with Step 1 – Dry Matter Requirement Per Head and proceed through each of the 7 steps.
Steps to Calculate Carrying Capacity
Click on each step in the calculation for more details.
- Dry matter required per head
- Growing season acres required per head
- Stockpile grazing acres required per head
- Hay production acres required per head
- Carrying capacity for the growing season
- Carrying capacity for growing season and stockpile grazing
- Carrying capacity for extended season grazing and hay production
Refer to the Bale Grazing and Stockpile Grazing publications at go.wisc.edu/extensiongrazing for more information on implementing these practices.
Dry Matter Required Per Head
Growing Season Grazing Acreage Required Per Head
Stockpile Grazing Acreage Needed Per Head
Hay Production Acreage Needed Per Head
Carrying Capacity for Growing Season Grazing
Carrying Capacity for Extended Season
Growing Season + Stockpile Grazing
Carrying Capacity for Extended Season and Hay Production
Growing Season + Stockpile Grazing + Hay Production
What if I have more animals than my land can support?
Determine the number of animals over carrying capacity and decide whether the goal is to reduce or maintain the herd size. If the goal is to keep them, you can:
- Expand pasture base – multiply the total acreage per head in steps 5, 6, or 7 by the additional animals to determine how much land to convert, lease, or purchase for pasture.
- Purchase extra feed – multiply dry matter allocated per head from step 1 by the number of additional animals to determine how much hay is needed.
Updated: March 5, 2026
Contributors:
- Adam Abel, grazing specialist, USDA-Natural Resources Conservation Service
- Derrick Raspor, resource conservationist, USDA-Natural Resources Conservation Service
References
- Chasen, E.M. 2023. Predicting pasture yield in Wisconsin: Yield potential predicted by soil, grazing management, and grass species-clover mix. Web-application. Grassland 2.0 project. University of Wisconsin-Madison. https://connect.doit.wisc.edu/pasturePrediction/
