When we talk forages for pigs, the conversation is slightly different than larger ruminant animals like horses and cows. Pastures and forages can be vital in swine feeding programs, but they can’t be the primary source of nutrition. 

Pigs are monogastric animals with a single central stomach compartment. Without a rumen and the associated microorganisms, pigs cannot efficiently break down the cellulose in plant material and don’t receive microbial protein and the resulting amino acids. Therefore, pasture and hay should serve as a nutritional supplement to grain, and grazing areas should be a playground for physical activity. 

Our forage guide will help you choose ideal, high-quality species for your forage crops, whether pasturing your pigs or feeding them hay. 

Benefits of Allowing Pigs to Forage

Pasture-based pork production offers essential benefits to the animals. Even though pasturing can’t meet all of your animals’ dietary needs, pasture access can still be a great addition to your hog’s management plan.

Improved Mental Health and Well-Being

Pigs perform natural swine behaviors, like rooting, wallowing, and exploring while grazing. These behaviors help to minimize their stress levels, which in turn increases their overall well-being. Lower stress levels are associated with better immune function and overall health.

In most cases, happier pigs are healthier pigs! 

Pork Quality

Pastured pigs can be hardier and more resistant to parasites, and their pork can have a better flavor. Studies also show the nutritional value of pork from pastured pigs is higher than pork from conventionally raised pigs.

• 2.4 times more omega-3 fats 
• 60% lower omega-6 to omega-3 ratio 
• 1.3 times higher poly-unsaturated fats compared to saturated fats 
• 8% higher protein 
• 2 times more vitamin E 

Reduced Feed Costs

Lastly, any time your pigs are put out on pasture, you reduce your supplemental feed costs, a significant portion of animal production. A well-managed pasture that helps fulfill the dietary requirements of your hogs is an economic benefit. 

According to Tony Nye of the Ohio State University Clinton County Extension, you can anticipate replacing 50% of the grain for pasture with gestating sows and 10 to 20% of the grain for growing pigs.

Qualities to Look for When Choosing a Forage

Nutritional Value

To meet the nutritional needs of your animals, it’s essential to choose high-quality forages that offer a balance of crude protein, fiber, nutrients, and minerals. When well-managed, they’ll provide a fantastic feed source to help supplement grain rations. 

Forage Yield & Consistent Growth

Beyond nutrition, choose forages with good dry matter yields and consistent, persistent growth habits. High-yielding plants are crucial to producing sufficient feed for your pigs, and efficient, consistent growth keeps your pasture productive all season. 

A primary goal with pastures is to provide feed for your animals from spring to fall without any slumps in growth.

Swine Feeding Habits

Pigs have specific grazing preferences and foraging habits that may differ from other livestock types. 

Grazing Preferences

Pigs prefer areas with diverse vegetation, which allows them to find a wide range of nutrients.

They enjoy grazing on grasses, legumes, and other broadleaf plants, consuming leaves and stems. When available, they will also eat seeds, fruits, and nuts.

Foraging Behavior

Pigs are omnivorous and naturally tend to root and dig in the soil with their snouts for food. This behavior is known as rooting. They forage for various food sources, including roots, tubers, insects, small animals, and plant material.

Ideal Forages For Pigs

With many different forages available, you can create a custom swine pasture tailored to your animals’ needs. 

Always remember that when looking at the best options for your pics, think about what species are adapted to your local climate and the soil you have. Consider your management situation and choose forages that work best for you. 

Legumes

Pastures containing a large percentage of legumes are typically the norm for pork producers. Legumes make excellent forage choices because of their higher energy and nutrient content. They can provide swine with adequate nutrients except vitamins D and B12. 

• Alfalfa is a top forage choice for hogs. Its high protein and calcium content help support bone strength and rapid muscle development. It also serves as an excellent energy source, helping animals stay warm during cold periods.
• Winter King II Alfalfa
• Transition DC Alfalfa

• Ladino, white, and red clover provide essential amino acids that improve feed conversion and muscle growth. 

• 390 HyQual Brand Alfalfa
• Ladino White Clover
• Dutch White Clover
• Crimson Annual Red Clover
• 990 Elite Red Clover
• Lespedeza comes through in the summer, providing fresh forage when other plants may slow their growth because of the heat. Animals may not prefer it as much as alfalfa and clovers, but it fills a vital pasture need.
• Forage soybeans are less valuable as green forage than alfalfas and clovers, but they supplement pastures well, especially for summer feeding. They can be grazed from flowering to just before maturity. 

Cool-Season Grasses

Cool-season grasses make excellent pasture forages. They grow abundantly in spring and fall to provide cool-season forage and tend to retain forage quality better than warm-season types.

• Forage Kentucky bluegrass is very palatable, highly nutritious, and tolerant of frequent, close grazing. It’s suitable for pastures because of its low-growing habit and tendency to form a tight sod.
• Ryegrasses are highly nutritious and recover rapidly from frequent, close grazing. They establish quickly and are tolerant of rocky or poor soils. Perennial types are better for cooler, northern climates; annual ryegrasses are not cold-tolerant.
• Crusader Italian Ryegrass
• Tetraploid Annual Ryegrass
• Arelio Perennial Ryegrass
• Tetilia Italian Ryegrass
• High Sugar Perennial Ryegrass
• Endophyte-free tall fescue (Fawn Tall Fescue, Cajun II, Kentucky 32.) has excellent fall productivity to extend the grazing season and is moderately tolerant of continuous grazing. It is also good at resisting weeds, insects, and diseases. 
• Orchardgrass is a highly productive forage option. It’s clean and sweet-smelling, with excellent palatability. Deer Creek Seed’s Amplify Brand Orchardgrass has moderate winter hardiness and grows quickly.
• Timothy grass is full of fiber for improved gut health and has a balanced ratio of calcium and phosphorus, helping to maintain bone health. It produces abundant leaves in midsummer when other forages slow their growth due to the heat.
• Small grains such as wheat, rye, oats, and barley are often sod-seeded into dormant warm-season grass pastures to extend the grazing season. 
• Winter Rye
• Falcon Brand Spring Oat
• Arctic Brand Forage Deer Oat
• Robust Spring Barley

Warm-Season Grasses

Warm-season grasses are valuable forages for pastures, especially in Northern regions. They can provide green grazing during the summer slump when cool-season grass growth slows. These grasses generally have higher fiber content and lower crude protein than cool-season grasses.  

• Bermudagrass produces large amounts of dry matter and can offer high nutritional value for your animals. It tolerates grazing pressure, and its crude protein content responds well to nitrogen fertilizer applications. Some cold-hardy forage varieties that establish well from seed are available.
• Crabgrass makes an excellent forage, especially during the hot, dry months when other forages hit that summer growth slump. It is typically higher in nutritional value and digestibility than other warm-season grasses.

Forbs

Forbs are broad-leaved herbaceous plants that grow naturally in grasslands, meadows, and pastures. Unlike grasses, characterized by narrow leaves, forbs have broader leaves and diverse flowering patterns. Forbs encompass various plant species, including wildflowers, herbs, and non-grass vegetation.

Compared to grasses, they often contain different nutrients and secondary compounds that can complement the pasture’s overall nutritional profile.

• Chicory is a high-quality, palatable forage with crude protein levels ranging from 10% to 32%. New plantings can withstand high grazing pressure and produce 2 to 3 tons of dry matter per acre; established stands produce 4 to 6 tons per acre. 

 

Photo Credit: Wikimedia Commons | CC BY-SA 2.0 | no changes made 

 

• Brassicas are annual crops that can extend the grazing season into the late fall or early winter and are fantastic for rooting. They include rape and turnips like Purple Top, York Globe, and Seven Top. 

Forages to Feed in Moderation

• Birdsfoot trefoil contains bitter tannins, which some animals avoid grazing. The high tannin content, Fusarium contamination, or prussic acid accumulation in some varieties may also trigger colic or mild gastrointestinal discomfort.

Forages to Avoid With Pigs

• Bracken fern contains thiaminase, an enzyme that breaks down thiamine (vitamin B1). Ingesting large amounts of bracken fern can cause thiamine deficiency, resulting in neurological issues.
• Nightshade plants, such as horsenettle and black nightshade, can be toxic. They contain solanine, which can cause symptoms like drooling, diarrhea, and respiratory distress.

Are Grasses or Legumes Better Forages for Pigs?

Pros of Forage Grasses

✓ High fiber content

✓ Long growing season

✓ Tolerant of frequent, close grazing

✓ Stands establish quickly

✓ Tolerant of a broader range of soils

✓ Better drought tolerance than legumes

✓ Can be grazed or used for hay

Cons of Forage Grasses

✗ Lower crude protein content

✗ Less trampling tolerance

✗ Lower dry matter yields

 

Photo Source: Jeffrey Surianto | Pexels

Pros of Forage Legumes

✓ High in crude protein

✓ Higher tolerance of extensive animal grazing

✓ Nitrogen fixation improves soil fertility and lowers fertilizer costs

✓ Improved palatability and digestibility

✓ Useful for grazing or hay

Cons of Forage Legumes

✗ Less tolerant of weather extremes (heat, cold, drought)

✗ Higher management needs

 

Photo Source: Wikimedia Commons

Benefits of Growing Mixed Species Pastures

There are advantages and drawbacks to growing mono stands of grasses and legumes. Since both offer excellent forage potential, it’s hard to say one is better. 

• Cool-season grasses have a more extended growing season—they produce earlier in the season and later in the fall than legumes—but they slow down in the summer, offering very little grazing material. 
• Warm-season grasses produce during the summer heat but aren’t as high quality as cool-season. 
• Legumes have the best crude protein levels but require more intensive management and aren’t as tolerant of heat, cold, and drought.

Because of this, many producers opt to plant mixed forage pastures that include multiple grass or legume species, or legumes and grasses to reap more benefits, including: 

• Increased dry matter weight and crop yield 
• Reduced weed competition
• Improved distribution of forage growth through the season
• Greater adaptability to weather conditions 
• Reduced nitrogen fertilizer needs from the leguminous nitrogen-fixation
• Less winter kill and frost heaving with thicker sod

Looking for high-quality pasture mixtures? Deer Creek Seed offers the following selections that are great for swine.

• Pastureland Dry-Land
• Pastureland Over-Seeder South
• Premium Grass Base Forage Mix

Stocking Rates for Swine Pastures

Having an acceptable animal body weight per acre is vital to successfully managing your pasture stand (s). Putting too many animals on a pasture puts too much pressure on it and negatively impacts production and longevity. 

Swine Pasture Stocking Rates
Sows with litters	6 to 8 per acre
Weaned pigs to 100 pounds	15 to 30 per acre
100 pounds to market	10 to 20 per acre
Gestating sows	8 to 12 per acre

Rotational Grazing for Better Pastures

Rotational grazing, or moving animals between different pasture areas or paddocks, is utilized with many types of livestock, especially large animals like horses and cattle that graze forages quickly and cause trampling. While pigs don’t graze as quickly, rotational grazing is still essential, as their rooting tendency can quickly damage pastures.

Moving animals to different paddocks allows the forage plants in previously grazed sections to recover and regrow. Rotating them to new sections also disrupts some parasitic life cycles, reducing the need for chemical interventions.

Recommended Rotational Grazing System

Rotational grazing systems come in all shapes and sizes, taking on different forms to meet the needs of a producer and what they can manage. However, an ideal rotation has a minimum of four paddocks surrounding a single dry lot. 

The dry lot contains shelter, the main feed, and a water source. Your pigs should always also have access to adequate shade and wallows. All paddocks connect to this central “sacrifice” lot via gates and always have access to it, no matter the paddock they’re grazing.

Grazing animals should always be in the paddock with the tallest forage, and the gates to all others should be closed. They can graze this pasture area until the ground is about twenty percent bare or until the pigs begin rooting more than grazing. This is usually 3 to 5 days, but it can be longer if you’ve broken your pasture into bigger paddocks. 

Once the paddock is grazed, move your animals to the next one ready and shut the gates to the previous paddock. Continue this system until all paddocks are grazed, and then begin again.

Forage Quality Analysis

If you’re running quality analysis on forages, it’s helpful if you understand the lab report. Crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) are commonly used when evaluating forages, whether pasture, hay, or silage. Total digestible nutrients (TDN), net energies, and mineral concentrations are also frequently reported.

Understanding Crude Protein (CP)

Protein is a vital component of forages. It is the source of energy in feed and provides nitrogen and essential amino acids to the animal. 

Forages and other feeds are analyzed for crude protein (CP), the combined percentage of true protein and non-protein nitrogen. This number indicates the forage’s ability to meet your animals' protein needs and is useful when developing a ration for your livestock.

• Legume forages have 20 to 24% CP.
• Spring and summer grass pastures contain upwards of 20% CP. 

Understanding Fiber Content: Neutral Detergent Fiber (NDF) & Acid Detergent Fiber (ADF)

Another critical measure of a forage’s quality is the amount of fiber in the plant material, as fiber is the predominant factor in forage digestibility. Structural components like cellulose, hemicellulose, and lignin are included in the fiber content.

Generally speaking, fiber levels and digestibility are inversely correlated. Lower fiber means higher digestibility; higher fiber means lower digestibility.

Higher digestibility typically means higher energy value for the animal and better forage quality. Low fiber values also suggest that forage is easier to chew and more palatable (i.e.,  animals will consume more).

Neutral detergent fiber (NDF) and acid detergent fiber (ADF) measure a forage’s cell wall composition. 

• NDF measures hemicellulose, cellulose, and lignin levels and is typically used to predict intake potential. 
• In grasses, NDF < 50% is considered high quality; NDF > 60% is low.
• In legumes, NDF < 40% is considered good quality; NDF > 50% is considered poor.
• ADF measures cellulose and lignin and is commonly used to calculate digestibility.
• Forages with less than 35% ADF are typically considered high-quality.

Grasses typically contain more NDF and ADF than legumes because of greater lignification. However, you see a wide variability of NDF and ADF within grass species. And the hemicellulose, cellulose, and lignin amounts typically increase in all forages as they mature.

Understanding Moisture and Dry Matter (DM)

Dry matter (DM) is the non-moisture portion of a forage; it indicates the nutrient concentration available to your animals. The higher the dry matter, the higher the nutrients.

• Pastures typically contain 75 to 90% moisture content or 10-25% DM, regardless of the forage type. 

Understanding Total Digestible Nutrients (TDN)

Total digestible nutrients (TDN) estimates the energy content of a food source and is the sum of the digestible fiber, protein, carbohydrates, and lipids that supply energy to the animal. 

TDN is directly correlated to digestible energy and is often determined using CP and ADF values. 

• Low quality usually contains 45 - 52% TDN
• Mid-quality usually contains 52% - 58% TDN
• High quality usually contains greater than or equal to 58% TDN

Understanding Energy Content

The energy content of a forage can get tricky when you dive into it. At the fundamental level, the energy content of a forage (or other feed source) is the energy available to an animal that can be used for activities like growth, breathing, lactation, etc. 

However, there are different ways to express energy content and some controversy surrounding this aspect of forage quality analysis. 

• Gross energy (GE) is the total energy content of a forage. Not all gross energy is usable by an animal because of digestion and metabolism.
• Digestible energy (DE) is the energy of a forage absorbed by an animal, accounting for the energy lost in feces during digestion. 
• Metabolizable energy (ME) is the energy left after accounting for the energy lost during digestion from the production of urine and gases. It’s the energy available for maintenance, growth, and production. 
• Net energy (NE) represents the energy utilized by the body for maintenance, growth, and production. It’s calculated by subtracting all energies lost to metabolic processes from the metabolizable energy.

In America, the energy content of a forage is usually expressed as digestible energy (DE) and is reported in megacalories per pound (Mcal/lb). A forage's crude protein and ADF content reasonably estimate the DE. 

However, DE is considered quite archaic because there are significant differences in how digested energy is utilized from different forages and across livestock species. Keep this in mind and view DE values as an estimate.

Understanding Mineral Content

The total mineral content is reported as “ash” in a forage analysis. Macronutrient concentrations of the macronutrients are expressed as percentages (%) or grams per pound; trace mineral concentrations are expressed as parts per million (ppm) or milligrams per pound.

All minerals reported on a forage analysis are essential nutrients for overall health. It’s also necessary that some nutrients occur in balance with others.

• Calcium and phosphorus should be in a 2:1 ratio of approximately two parts calcium to one part phosphorus.
• Zinc and copper should have a 4:1 balance, with more zinc in the plant than copper.
• Iron levels should be no higher than 500 ppm; excess iron can inhibit the absorption of other nutrients and, in extreme cases, trigger insulin resistance. Legumes tend to have higher iron levels than grass forages.

Differences in Hay Quality Versus Quality of Fresh Forages

If you cut or mow forages for later use as hay, there will inherently be some nutritional differences. These differences are primarily because fresh pasture grasses and legumes have a considerably higher water content. The higher moisture, in turn, affects the concentration of other dietary components. 

Moisture Content

• Pasture plants typically contain 75 - 90% water 
• Hay contains 10 - 12% moisture

The moisture content difference is the leading reason hay can be stored successfully for periods without seeing mold growth. 

Crude Protein (CP)

• Grass pastures contain 10 - 20% 
• Legume pastures contain 20 - 24% protein
• Grass hays contain 6 - 10%
• Legume hays contain 12 - 20%

As you can see, fresh pasture forages typically have higher crude protein levels than hay, and their overall quality is generally better. 

After forages are harvested, their proteins undergo proteolysis, breaking down into nonprotein nitrogen-based compounds like ammonia and urea. This breakdown reduces the CP and changes the amino acid profile of hay.

Notably, the crude protein of legume and grass pastures also declines as the season progresses and plants mature. 

Fiber and Digestibility

• Early pasture forages have better digestibility than mature plants
• Fresh pasture is more digestible than hay harvested at the same time 

These digestibility differences are inversely related to fiber content. Lignin, cellulose, and hemicellulose increase as plants age, making them harder to digest.

Vitamin Levels

• Pasture is higher in vitamins A, C, and E levels than hay.

After forage is harvested, exposure to oxygen and sunlight degrades these essential nutrients. This degradation continues during hay storage, leading to significantly lower vitamin levels than fresh forages.

Physical Assessment of Forage Hays

While pigs don’t eat as much hay as cows and horses, it can still contribute to their diets during winter when fresh forages aren’t available. When choosing hay for them, a visual inspection of the quality is important. You’ll want to look at color, smell, maturity, leafiness, and foreign matter.

Color

Color is one of the first things you check when inspecting forage. Different colors can tell you varying things about the hay’s quality. If you’re questioning quality, you can always do a forage analysis.

You preferably want the hay to be green, which indicates good nutrient content, but it should not be the primary or only focus. Weeds also stay green when they’re dried, which can give a false indication of nutritional value. 

Light or pale yellow on the bale’s outside indicates sun-bleaching. The bleached areas on the outside will be lower in carotene and less palatable. This isn’t necessarily bad as long as the sun-bleaching doesn’t penetrate the bale more than one-half to a full inch. Bleaching doesn’t reduce the nutrient value too much until it extends beyond that inch mark.

A completely yellow bale typically indicates the forage was too mature when harvested, and the hay will have reduced nutrient value and even poor palatability. 

Dark brown or black hay is usually a sign the forage was harvested and baled when wet. Under these circumstances, fungi and bacteria feed on the nutrients, producing heat that darkens the hay. The bale may also have a distinctively sweet odor, almost like caramel. 

Heat-damaged hay may contain bacteria, fungi, or mold, potentially producing dangerous mycotoxins. It will also have reduced nutritional value, digestibility, and palatability. 

Pro tip: Remember that red clover naturally turns brown as the hay dries. It doesn’t indicate poor quality but is a good reminder to identify the forage species when evaluating hay. 

Smell & Dust

Hay should have a clean, fresh, slightly sweet smell. It shouldn’t smell musty or stale. If it does, there’s a chance of mold within the forage, and you shouldn’t feed it to your animals. 

Also, check for excessive dust. If a bale creates a dust cloud as you move it, it can exacerbate or trigger respiratory ailments.

Maturity

As a forage plant matures, it becomes less nutritious. Lignin content in the cell walls increases, potentially decreasing the digestibility. Hence, you want younger forages. 

Look at the number and size of seedheads in grass-type hays and the number of flowers in legume hays. If you see very few seedheads or flowers or smaller seedheads, it indicates less mature, desirable hay.

There’s no need to worry about which cutting the hay is. The cutting number has much less impact on its nutritional value than the forage’s maturity when harvested.

Leafiness 

Take a look at how leafy the hay is within the bale. Leaves contain more nutrients, protein, and digestible carbohydrates than stems—you want your forage source to have plenty of leaves and fewer stems and seedheads.

You also want to note stem thickness, as this indicates the state of maturity of the harvested material. Hay with thick, coarse stems was harvested when it was more mature than the same species with finer stems. However, hay with fine stems that lack leaves means it was harvested too early and is immature. 

Foreign Matter

Lastly, look for foreign matter. You don’t want a bale full of material that adds no nutritional value to the hay or is inedible or dangerous for your pigs to consume. This includes insects, trash that could puncture the gut or cause an impaction, and dead animals that could introduce botulism neurotoxins. 

Deer Creek Seed Can Help With Your Swine Forage Needs

Whether you need help choosing forage species or picking the best seeds for your upcoming swine pasture, look no further than Deer Creek Seed! Our high-quality seeds grow productive, nutritious pasture forages, and our experts can help answer your questions about seed selection or crop management.

Deer Creek Seed aims to provide you with the highest quality seed at competitive prices and exceptional customer service. Our staff works diligently to serve our customers! 

Additional Resources

1. Interested in more information on adding rape to your swine pasture? The University of Missouri Extension covers seeding and fertilization. 
2. When raising pigs, it’s important to understand the differences between monogastric and ruminant animals. Oregon State University's article on the benefits and challenges of raising pigs on pasture covers the basics.
3. Learn more about the four pasture management systems from Penn State University, including the basics of a hogged-down system. 
4. Crabgrass seems unlikely as a pasture grass, but Rutgers University researchers have shown the weed’s strengths make it a great choice for summer forage. https://ker.com/equinews/researchers-eye-crabgrass-as-a-pasture-plant-for-horses/
5. Rotational grazing doesn’t have to be confusing with this helpful guide from Iowa State University’s Extension and Outreach.
6. Deer Creek Seed takes the guesswork out of determining how and when to harvest forages for hay or silage.