Location: Animal Parasitic Diseases LaboratoryTitle: Modulation of the intestinal environment, innate immune response, and barrier function by dietary threonine and purified fiber during a coccidiosis challenge in broiler chicks Author
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2012
Publication Date: 11/1/2013
Citation: Wils-Plotz, E.L., Jenkins, M.C., Dilger, R.N. 2013. Modulation of the intestinal environment, innate immune response, and barrier function by dietary threonine and purified fiber during a coccidiosis challenge in broiler chicks. Poultry Science. 92:735-745. Interpretive Summary: Avian coccidiosis is an intestinal disease of poultry that leads to poor weight gain and lower feed utilization. At present, the disease is controlled by medication of poultry feed with anticoccidial drugs or the administration of live vaccines to newly hatched chicks. The drugs prevent the causative organism, protozoa in the genus Eimeria, from invading and developing in host cells. Both control measures have some limitations and alternative methods that rely on organic feed additives are highly desirable. The purpose of this study was to determine if supplementing poultry feed with the amino acid threonine would elicit higher levels of immunity in chickens against coccidiosis. It was found that threonine did in fact cause higher levels of immunity, as measured by the release of immune-stimulating molecules, in chickens infected with Eimeria parasites, without negatively affecting growth of broiler chicks. These findings indicate that amino acid supplements to poultry feed may be beneficial to chickens in resisting coccidiosis.
Technical Abstract: Coccidiosis is a major contributor to economic losses in the poultry industry due to its detrimental effects on growth performance and nutrient utilization. We hypothesized that the combined effects of supplemental dietary Thr and purified fiber may modulate the intestinal environment and positively affect intestinal immune responses and barrier function in broiler chicks infected with Eimeria maxima. A Thr-deficient basal diet (3.1 g of Thr/kg of diet) was supplemented with 70 g/kg of silica sand (control) or high-methoxy pectin and 1 of 2 concentrations of Thr (1.8 or 5.3 g/kg of diet; 4 diets total), and fed to chicks from hatch to d 16 posthatch. On d 10 posthatch, chicks received 0.5 mL of distilled water or an acute dose of Eimeria maxima (1.5 × 10(3) sporulated oocytes) with 6 replicate pens of 6 chicks per each of 8 treatment combinations (4 diets and 2 inoculation states). Body weight gain, feed intake, and G:F increased (P < 0.01) with addition of 5.3 g of Thr/kg of diet. Eimeria maxima schizonts were present only in intestinal tissue sampled from infected birds (P < 0.01). Weights of cecal digesta were highest (P < 0.01) in pectin-fed birds, and ceca with the heaviest weights also had the highest concentrations of total short-chain fatty acids. Expression of interleukin-12 in ileal mucosa was highest (P < 0.01) in infected birds receiving the control diet with 5.3 g of supplemental Thr/kg. In cecal tonsils, interferon-gamma expression was highest in infected birds receiving the control diet (fiber × infection, P < 0.05); interferon-gamma expression was lowest in infected birds fed the high Thr diet (Thr × infection, P < 0.05). There were no differences due to infection or Thr supplementation for cytokine expression in birds fed pectin-containing treatments. Overall, we conclude that although pectin has some protective function against coccidiosis, Thr supplementation had the greatest effect on intestinal immune response and maintenance of near normal growth in young broiler chicks infected with E. maxima.