Clays have been used widely in both swine and poultry diets to prevent the deleterious effects of mycotoxins on productivity. University of Illinois research suggests dietary clays can alleviate diarrhea caused by E. coli in weaned pigs.

Clays have been approved in the United States as flow agents or anti-caking compounds at a level not to exceed 2% of the complete feed. Field observations suggest using clay products in the feed also has an anti-diarrheic effect in weaned pigs.

To test these observations, University of Illinois scientists conducted two experiments.

In the first trial, 48 weaned pigs were placed on one of four dietary treatments, and four days later, half of the pigs fed each diet were challenged with a pathogenic F18 E. coli which mainly causes postweaning diarrhea.

The four diets included a negative control without clay and clay (smectite) fed in three regimens: 0.3% of the diet, 0.6% of the diet or 0.3% of the diet introduced at the time of challenge. The diets contained no antibiotics, spray-dried plasma or zinc oxide.

In the E. coli-challenged groups, all three clay treatments reduced diarrhea scores (1 = normal to 5 = watery diarrhea), frequency of diarrhea scores 3 or higher and populations of the pathogenic E. coli.

In the second trial, 128 weaned pigs were placed on one of eight dietary treatments, and four days later, half of the pigs fed each diet were challenged with a pathogenic F18 E. coli.

The eight diets included a negative control without clay and seven clay treatments: three different clays (smectite, kaolinite or zeolite) fed individually or in all possible combinations to total 0.3% of the diet.

In both experiments in all of the E. coli-challenged groups, clay treatments reduced diarrhea scores and frequency of diarrhea (Figure 1).

The dietary clays consistently reduced populations of the challenge organism in feces, indicating that the effect of the clays was not simply adsorbing water and thereby chaning the appearance of the feces (Figure 2).

In short, the two studies showed that all of the clay treatments provided some protection against postweaning diarrhea, but didn’t affect growth rate of pigs. There were no clear and consistent differences among the clay treatments.
And researchers concluded the clays consistently reduced the frequency and severity of diarrhea of weaned pigs experimentally infected with a pathogenic E. coli.

Researchers: Minho Song, Yanhong Liu, Juliana Soares, Tung Che, Orlando Osuna, Carol Maddox and James Pettigrew, University of Illinois; Milwhite, Inc., Brownsville, TX. For more information, contact Pettigrew by phone (217) 244-6927, fax (217) 333-7861 or e-mail jepettig@illinois.edu.