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Swine & U Column: UMN Organic Swine Research Update

By Diane DeWitte, Extension swine educator
Originally printed in The LAND – as November 12/November 19, 2021 Swine & U column

Today’s consumers seek to know the origin of their food, and in response, more and more small and niche farms are raising pigs to supply natural pork or organic pork for local customers. Very little university research has been conducted in this area of pig farming. The University of Minnesota’s Yuzhi Li, funded by a succession of USDA National Institute of Food & Agriculture (NIFA) grants, has investigated alternative feed grains for organic pigs, the prevalence and control of parasites in pastured pigs, and has embarked on a new organic rye and swine research study.


All pigs grown in the early 1900s could have been considered ‘organic’ by today’s definition. The United States Department of Agriculture (USDA) manages the US organic crops and livestock program and issues certification to farms who meet the organic livestock standards.

USDA’s organic livestock standards include these elements (from the USDA website at
  • Pigs must be managed organically from the last third of gestation.
  • Animals must be allowed year-round access to the outdoors except under specific conditions (i.e. inclement weather)
  • Pigs must be raised on certified organic land meeting all organic crop production standards.
  • Animals must be fed 100% certified organic feed, except for trace minerals and vitamins used to meet the animal’s nutritional requirements.
  • Pigs must be managed without antibiotics, added growth hormones, mammalian or avian byproducts, or other prohibited feed ingredients (urea, manure or arsenic compounds).
  • Bedding used in organic livestock must come from organically produced crops (i.e. straw or corn stalks).

Some vaccines are allowed in certain stages of breeding swine, and breeding sows are allowed to be treated with synthetic de-wormer in the first and second trimester of gestation.

In organic production, some prohibited substances are allowed if preventative strategies fail and the pigs become ill. Those pigs are not allowed to be marketed as organic after they recover.

In addition, organic animals must be raised in a way that accommodates their natural behavior:

  • Access to outdoors
  • Shade
  • Shelter with clean dry bedding
  • Space for exercise
  • Fresh air
  • Clean drinking water
  • Direct sunlight


Managing swine intestinal parasites is an obstacle for organic pig farmers because there is a lack of organically-approved options for controlling parasites. Dr. Li’s 2019 project was developed to identify what kind of parasite load exists on organic swine farms, and to determine the effectiveness of some organic-friendly parasite management strategies.

Dr. Li, worked with researchers at the Rodale Institute and Kutztown University, both at Kutztown, Pennsylvania, and set up a series of parasite mitigation practices to learn how effective these would be for organic pig farmers.

  1. Manure Composting: Manure and swine bedding was amassed into compost piles in January, June, and November to learn what amount of time and temperature is required to inactivate worm eggs. This could be a manure-handling step which could neutralize eggs/larvae and reduce the parasite load on pasture or cropland where the manure is spread.
  2. Biofumigation: Brassicaceae is a family of plants which includes mustard, rapeseed, cress and many more. These plants contain a compound, glucosinolate, which, when the plant is chopped up, is transformed into isothiocyanate (ITC). ITC is toxic to bacteria, fungi and nematodes, and has promise as a killer of intestinal parasites in soil. The plants are mulched or pulverized with a flail mower at flowering, when the glucosinolate levels are high. The broken plants are then immediately incorporated into the soil for maximum ITC effectiveness.


During the previous organic swine project, Dr. Li and her team visited nine organic swine farms in four states: Minnesota, Iowa, Wisconsin and Pennsylvania. On these visits, samples were collected from feeder/growing pigs, finishing pigs, and the breeding herd. Manure, soil and bedding were gathered at each farm and analyzed for the presence of parasites.

Three common swine worms were identified in the samples collected.

  1. Ascaris suum. Ascaris is known as roundworm and is a common parasite in pigs. A pig consumes the roundworm egg from the soil or pasture, after which it develops and hatches in the intestines. It can travel to the pig’s lungs or liver, and a common symptom of roundworm infection is that the pig has a cough.
  2. Tricuris spp. Tricuris is another familiar swine parasite commonly known as whipworm. The pig becomes infected with Tricuris by consuming eggs found in the environment. The worm hatches and grows within the pig and sheds eggs via feces. In adult pigs, this parasite causes decreased growth and thriftiness.
  3. Oesophagostomum spp. Oesophagostomum are a nematode which in swine are common nodular worms. These worms are generally consumed by the pig in the larval form.

These three are the most well-recognized swine intestinal parasites and are very regularly found in pigs raised on pasture and outdoor settings.


Fecal sample collection at nine organic farms this summer yielded these results:

Prevalence across farms (% farms)
Eight of the nine farms were infected with parasites
  • Oesophagostomum: 56% farms infected
  • Ascaris: 78% farms infected
  • Tricuris: 44% farms infected
Prevalence on infected farms (% pigs)
  • Oesophagostomum: 60 - 70% pigs/sows infected
  • Ascaris: 50% pigs infected
  • Tricuris: 25% sows infected; 40% pigs infected
Parasite load on infected farms
  • Sows had higher load of Oesophagostamum than pigs
    • 371 epg vs. 60 and 176 epg (eggs per gram)
  • Pigs had heavy load of Ascaris
    • 1,733 epg for feeder/growing pigs
    • 1,198 epg for finishing pigs
    • 0 for sows
  • Trichuris was found in all stages
    • Relative low level
    • 55, 67, 79 epg (for sows, feeder/growing, and finishing pigs)
These results showed that there is a large variation among farms. Organic farms have a wide variety of management protocols, including deworming within USDA organic standards, and care and cleaning of the barn and bedding environment. When considering the effect of parasite infection on pig performance, this study found that there is no obvious effect when infection load is low, but younger pigs may be more vulnerable to infection


Dr. Li and a multidisciplinary team of UM associates recently were awarded a new USDA-NIFA grant to investigate hybrid rye production and its uses in raising organic pigs. The Minnesota project is part of a federal Organic Agriculture Research and Extension Initiative (OREI) investment.

To help drive down expensive organic pig production feed and bedding costs and reduce negative environmental impacts, University of Minnesota will develop strategies to optimize winter hybrid rye production, evaluate nutritional value of hybrid rye fed to pigs, determine its effects on meat quality, and examine the economic and environmental impacts of integrating hybrid rye into organic pig production systems.

The project team includes University of Minnesota faculty members and Extension specialists from swine nutrition, agronomy, renewable energy, nutrient management, agriculture economics and meat science.

The grant is part of the U.S. Department of Agriculture’s (USDA) National Institute of Food and Agriculture (NIFA) investment of over $30 million for 33 grants that support farmers and ranchers who grow and market high-quality organic food and fiber. NIFA’s investment in Organic Agriculture Research and Extension Initiative projects funds research, education and extension efforts to improve yields, quality and profitability for producers and processors who have adopted organic standards. Dr. Li’s project was awarded $1,433,820 and will take place at the UM West Central Research and Outreach Center, Morris, MN, over the next two years.

The project has already begun with the planting of organic rye plots at Morris. Great soils and rains have yielded an excellent stand of hybrid rye which will provide grain and bedding for the organic swine portion of the project next summer.

Minnesota’s organic swine producers can benefit from this project because winter rye has the potential to reduce costs as an on-farm source of feed and bedding. Its value has not been previously investigated, so this research will add more information to the education of organic pig farmers across the U.S.

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