Chicks received either a diet supplemented with pectin or a Thr-deficient control diet and either 75 percent or 125 percent of the previously determined optimal Thr supplement of 6.8 g/kg. Within each dietary treatment, one group of chicks was inoculated with E. maxima; the other was not.
"The goal was to determine the interaction between dietary fiber and dietary threonine, knowing that pectin was going to negatively affect digestion and threonine was going to positively affect intestinal health," Dilger explained.
Growth and feed efficiency were monitored for 16 days; then ileal tissue, mucosal scrapings, and the ceca (the part of the digestive tract used for water absorption and fermentation) were collected. Researchers looked at growth performance, morphological changes in the intestine, changes in the cecal environment, and gene expression in the ceca and mucosa.
"The most important part of the story was the cytokine response to the acute coccidiosis infection," Dilger said.
Cytokines regulate how the immune system communicates with the rest of the body and adjust the immune response. Interleukin-12 (IL-12) expression in the ceca was increased in birds fed the control diet with high threonine. Interleukin-1 beta expression increased with infection but only in birds fed the low-Thr diet.
Expression of interferon gamma (IFNG), a protein made and released in response to the presence of pathogens, increased in the ileal mucosa of birds fed high Thr, and was highest in the uninfected chicks. It increased with infection but only in control-fed birds
The researchers concluded that while pectin had some protective effects against coccidiosis infection, Thr supplementation had an even greater influence on the intestinal immune response and helped to maintain growth of chicks infected with
|Contact: Susan Jongeneel|
University of Illinois College of Agricultural, Consumer and Environmental Sciences