Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 2002
Publication Date: N/A
Interpretive Summary: Intestinal parasitism is a major stress factor that can lead to malnutrition and lowered performance and production efficiency of livestock and poultry. Coccidiosis, an intestinal infection caused by intracellular protozoan parasites belonging to several different species of Eimeria, costs the poultry industry more than $600 million in annual losses. Infection with coccidia parasites seriously impairs the growth and feed utilization of livestock and poultry. Current control method using drugs will need to be replaced by non-drug-dependent method due to an increasing drug resistance coccidia and increasing consumer's concern on the presence of drug residues in food supply. Therefore, alternative control strategy against coccidiosis needs to be developed. In this paper, ARS scientists, in collaboration with scientists at the University of Maryland, investigated the effect of probiotic dietary supplement on host immune response against coccidiosis. Results show for the first time that probiotics enhanced local cell-mediated immunity and increased host resistance against coccidiosis in chickens. These results provide optimism that increased basic knowledge on the interaction of nutrition and host immune system will generate novel control strategy against coccidiosis.
The effect of feeding a Lactobacillus-based probiotic on intestinal intraepithelial lymphocyte (IEL) subpopulations and subsequent protection against coccidiosis was investigated in broiler chickens. Day-old male broilers were fed standard rations without (CONT) or with (PROB) a commercial probiotic (Primalac). Differences in IEL subpopulations were assessed by flow cytometry at 21 days post probiotic treatment.At 25 days of age a group of randomly selected birds from each diet was inoculated orally with 10,000 (per bird) sporulated oocysts of Eimeria acervulina and kept on the same diets. Fecal material, sera, and intestinal washes were collected 10 days post challenge with E. acervulina. Birds on the PROB diet had more IEL expressing the surface markers CD3, CD4, CD8 and TCR than those of the CONT diet. The probiotic-fed chickens produced significantly lower oocysts(P 0.0001) compared to the untreated, control group(368 x 106 6in CONT vs. 89 x 106 in PROB). The IFN-gamma levels in both serum and intestinal secretions was not significantly different between the two groups. However, CONT group showed higher antibody levels against a recombinant coccidial antigen in the intestinal secretions than the PROB group. No significant difference was found in serum antibody levels against the same antigen. These results clearly indicate that the Probiotic bacteria impacted the local immune response as characterized by altered IEL subpopulations, and increased the birds' resistance to E. acervulina as reflected by reduced oocyst shedding.