Clean Up!: Many hog diseases may be prevented by clean water, clean feed in clean places, rotation of pasture: more cleanliness, less medicine

"Clean Up!" poster, 1920

Prior to the 1920s, farmers raised swine on permanent pastures or lots where generations of hogs had been kept before them. Over time, the soils in these pastures accumulated waste from many animals, some of which were carriers of intestinal parasites. Worm eggs that passed into the soil with hog droppings were picked up by the next season’s piglets, and parasite infections flourished.

Parasitic diseases made raising swine a difficult and financially risky enterprise. Stunted growth due to parasite infections meant farmers had to feed pigs longer before they were market-ready, adding to the cost of raising them. Not only did producers face the problem of poor returns for unfit stock, but some animals did not survive to reach the market. It was not uncommon for such losses to drive farmers out of hog production altogether. 

“In the general run of hogs in certain sections of the south 85 to 90 percent of livers go to the tank and the loins quite commonly penetrated by the parasite, thus destroying portions of the choicest parts of the hog.”  “The Possibilities for Swine Production in the South,” undated

Stephanurus dentatus(kidney worm of swine): worm imbedded in kidney of hog

Stephanurus dentatus (kidney worm of swine): worm imbedded in hog kidney

The McLean County System of Swine Sanitation, named for the place where it was developed and tested, was the first systematic method for controlling Ascaris suum infection in pig litters. The McLean system controlled not only worm infections, which were responsible for substantial losses to the swine industry, but it prevented other filth-borne diseases as well.

The McLean County System of Swine Sanitation was designed to prevent parasites from infecting new pig litters. The system consisted of four steps:

  1. Cleaning and disinfecting farrowing pens prior to each farrowing season (spring and fall).
  2. Washing sows before they were put in clean farrowing pens.
  3. Moving sows and their pigs to clean pastures, i.e., where no hogs had been kept for at least a year. Best practice included making sure the field had been cultivated since it was last used for raising hogs in order to eliminate prior contamination.
  4. Keeping pigs confined to clean pasture until they were at least four months old and more resistant to infections.

Resources:

“Accomplishments of Helminthological Investigations.” n.d. U.S. National Animal Parasite Collection Records.  Box 98, Folder 3. Special Collections, National Agricultural Library.

Andrews, John S. 1993. Animal Parasite Research in the Zoological Division, Bureau of Animal Industry, U.S. Department of Agriculture, Washington, D.C., 1923-1938. Beltsville, MD: Animal Parasitology Institute, BARC-East, Agricultural Research Service, U.S. Department of Agriculture.

“Conceptual Firsts Accomplished in Helminthological Investigations.” 1961. U.S. National Animal Parasite Collection Records. Box 98, Folder 3. Special Collections, National Agricultural Library.

Raffensperger, H. B. n.d. “Parasites of Swine (Treatment and control).” U.S. National Animal Parasite Collection Records. Box 98, Folder 3. Special Collections, National Agricultural Library.

Robbins, E. T. 1926. Cheaper and More Profitable Pork through Swine Sanitation: A Review of the McLean County System of Swine Sanitation on Illinois Farms during 1925. Circular 306. Urbana, IL: University of Illinois.

Schwartz, Benjamin. 1934. Controlling Kidney Worms in Swine in the Southern States. U.S. Department of Agriculture Leaflet 108. Washington, DC: U.S. Government Printing Office. https://archive.org/details/controllingkidne108schw.

“The Possibilities for Swine Production in the South.” n.d. U.S. National Animal Parasite Collection Records, Box 136, Folder 1. Special Collections, National Agricultural Library.

U.S. Department of Agriculture. 1924. Annual Reports of the Department of Agriculture for the Year Ended June 30, 1923. Report of the Secretary of Agriculture. Reports of Chiefs. Washington, DC: U.S. Department of Agriculture.

Walters, T. G. n.d. “Turn Your Feeds into Pork, Not Worms.” U.S. National Animal Parasite Collection Records. Box 136, Folder 10. Special Collections, National Agricultural Library.

Wilson, M. C. 1926. Swine Sanitation : Excerpts from 1925 Annual Reports of State and County Extension Agents. Extension Service Circular 22. Washington, DC: U.S. Department of Agriculture. https://archive.org/details/swinesanitatione22wils.