Clay supplements improve dairy cows immune response to aflatoxins

Cows exposed to aflatoxin and fed aluminosilicate clay supplement showed improvement in liver function and immune response.

In the fight against aflatoxin, dairy producers often turn to sequestering agents such as clay to reduce transference of the toxin into milk. It's an effective tactic, but a new study from the University of Illinois shows that clay has additional benefits for overall cow health.

"There has been a good amount of research showing the effect of clay supplements on milk quality and performance, but we took it a step further to look at how clay can help the cow's immune system," explained Russell Pate, doctoral student in the University of Illinois department of animal sciences and lead author on the study.

When incorporated into the diet, clay binds to aflatoxin, preventing it from being absorbed into the cow's bloodstream. Instead, Pate said, the bound clay-aflatoxin complex is simply excreted through the feces.

For the study, Pate and his collaborators looked at the effects of aflatoxin and aluminosilicate clay supplementation in four groups of lactating Holstein cows: (1) cows that weren't exposed to aflatoxin and were not fed clay (control), (2) cows that were exposed through an oral bolus and were not fed clay, (3) cows that were exposed and fed 4 oz. of clay in the total mixed ration and (4) cows that were exposed and fed 8 oz. of clay.

"We used two different concentrations of the product to see if adding more would have a greater effect on toxin transference to the milk," said Phil Cardoso, assistant professor in the department and co-author on the paper.

Cows fed the greater quantity of clay produced more milk with less aflatoxin M1, the form of the toxin that is excreted in milk.

Other researchers have shown similar results. What was new about the Illinois study was that Pate and Cardoso, along with co-author Devan Compart, looked at the effects of aflatoxin and clay on the liver through biopsies and at blood metabolites, the university explained. The measures provide a broader picture of overall health and immune function.

"By minimizing the amount of aflatoxin getting into the cow's bloodstream through the clay supplements, we wondered if that would help the cow's immune system stay stronger, in a sense. That hadn't been tested as much," Pate explained.

For cows that were exposed to aflatoxin and not fed the clay supplement, Cardoso said liver hepatocytes were severely inflamed, but in cows fed 8 oz. of clay, inflammation decreased substantially. In addition, indicators of liver functionality and immune response, such as glutamate dehydrogenase and alanine aminotransferase, tended to increase in the liver and the blood as clay concentration in the diet increased.

The team also looked at gene expression and found that a certain gene involved with protein production, known as MTOR, was negatively affected by aflatoxin challenge.

"With aflatoxin challenge, cows are producing less protein for themselves, for the milk, everything. Everything is made of protein. This is very instrumental," Cardoso said.

Ultimately, the researchers recommended clay supplements for aflatoxin challenge in dairy cattle, according to the news release.

"If you add clay to the diet, you will have a decrease in aflatoxin getting to the milk and will potentially be bolstering the immune system as well," Pate said.

The article, "Aluminosilicate Clay Reduces the Deleterious Effects of an Aflatoxin Challenge in Lactating Holstein Cows," was published in the Journal of Dairy Science. The authors included Pate, Devan Compart of PMI Nutritional Additives and Cardoso. The project was partially funded by PMI Nutritional Additives.