Postweaning diarrhea is a syndrome that has numerous causes affecting pigs 3-7 days after weaning. Rotavirus, salmonella and coccidiosis cause diarrhea in newly weaned pigs, but the major causes of E. coli are K88 and F18 strains.

Case Study No. 1

A 2,400-sow herd has three-site production with twice-a-week weaning of pigs at 17-21 days of age. Each nursery room receives two weanings or 1 week’s worth of pigs. Each nursery/grower site has a four-room building that receives four week’s worth of pigs. The three sites are separated by several miles; each site has its own water and washing equipment, but the same staff takes care of all the pigs.

Site A experienced severe diarrhea in weaned pigs. All four rooms were affected at 5-10 days after arrival. The owner had tried several different water medications with very poor results. Pigs were dying very soon after showing clinical diarrhea and most of the group was affected within a few days.

The site, procedures and personnel were thoroughly examined. Pigs with acute diarrhea were sacrificed and tissues submitted for diagnostics. The results showed an F18 hemolytic E. coli with LT toxin.

The review of procedures isolated several problems:

• A commercial hauler was used to transport pigs from the nursery/grower to the finisher. The truck had not been cleaned, pigs had been transported on the truck and were allowed to reenter the loading chute and the building.

• The staff was shorthanded on loadout day and didn’t change clothes after loading pigs.

• The power washer heating element was not working. Some rooms were washed with cold water and not disinfected before being reloaded with weaned pigs. Personnel did change clothes and boots routinely as they went between sites.

Retraining of unit personnel was initiated. To prevent site contamination or between-site contamination, farm staff was required to validate procedures. The affected site was the only one that showed signs in this system and was intensely cleaned and disinfected on the next turn. The system used F18 vaccine in all the pigs for two turns. Effort was made to use acidification of water and reduce other stress factors that trigger diarrhea outbreaks.

Case Study No. 2

A 200-sow, farrow-to-finish, single-site farm produced pigs in batches. Due to space/time restrictions and marketing opportunities, the farm changed from a 10-group system (batch every 14 days) to an eight-group system (batch every 18 or 19 days). With the system change, weaning age was increased to 19-26 days and weights to 14-20 lb. In spite of these changes, the producer and the feed supplier were reluctant to change the feeding program.

However, after the third-consecutive batch broke with severe scours after weaning, the producer was ready to make changes. Numerous water and injectable medications had virtually no response. Morbidity was approaching 100% and mortality was over 10% in one nursery group.

Tissues were submitted for lab testing from several recently weaned, untreated pigs with diarrhea. Pure hemolytic E. coli (untypable) producing STb and LT toxins was cultured, resistant to all antibiotics.

Water was acidified with citric acid, diet changes were made to accommodate the size and age of weaned pigs, and pigs were fed multiple times per day. Zinc oxide at 3,000 ppm was added to the feed. These actions provided noticeable improvements. The farm has not experienced a major break of postweaning diarrhea in over six months.

Discussion

E. coli organisms are ubiquitous and can be introduced into a herd by pigs, breeding stock, visitors, rodents, birds, contaminated feed, trucks, disposal vehicles, etc. Control these risk factors to reduce the incidence of disease using biosecurity and sanitation. Manage the environment for the newly weaned pig, keeping it warm and dry, especially in the first few weeks.

Match the pigs’ age, weight and general health status with the appropriate feed. Diets should be formulated to meet the nutritional needs of the genetic lines. Use of zinc oxide at high levels (3,000 ppm) reduces the ability of many E. coli serotypes to replicate in the gut.

Acidification of the intestine can reduce the binding of E. coli to the epithelial cells by using water-soluble products such as citric acid, formic acid, etc.

Be sure to consult your veterinarian when experiencing production or health challenges.