Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2003
Publication Date: 8/2/2003
Citation: Dalloul, R.A., Lillehoj, H.S., Shellem, T.A., Doerr, J.A. 2003. Intestinal immunomodulation by vitamin a deficiency and lactobacillus - based probiotic in eimeria acervulina - infected broiler chickens. Avian Diseases. 47:1313-1320. 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. New method to control chicken coccidiosis is needed since current strategy is not efficient. Previously a collaborative study with scientists at University of Maryland has shown that resistance in broilers to Eimeria acervulina (EA) was significantly reduced by vitamin A deficiency and enhanced by a probiotic (Lactobacillus-based) treatment. In the present study, feeding the probiotic significantly reduced oocysts and enhanced cell-mediated immunity to Eimeria. This study shows the importance of nutrient dietary supplementation such as vitamin A and probiotics as a new way to enhance host innate immunity against enteric parasites.
Technical Abstract: Previously we have shown that resistance in broilers to Eimeria acervulina (EA) was significantly reduced by vitamin A deficiency and enhanced by a probiotic (Lactobacillus-based). In the present 2 x 2 factorial study, a broiler starter ration was amended for vitamin A (control, C, or deficient, A) and probiotic status (-, P) to investigate their modulatory effects on the host immune system. Birds were inoculated orally with EA oocysts and disease susceptibility was evaluated by assessing fecal oocyst shedding. Humoral and local cellular mediated immunity were assessed by evaluating antibody and cytokine (IFN-Gamma and IL-2) levels in sera and intestinal secretions on a 3-day interval following inoculation. Fecal oocyst shedding was highest (P < 0.05) in A- birds, followed by AP, C- and CP. Feeding the probiotic reduced shed oocysts by 20% in A fed birds and by 26% in C fed birds. Intestinal IFN-Gamma was relatively constant in all treatment groups except for A- where it declined steadily and was lower (P < 0.05) from day 6 on. Serum IFN-Gamma levels fluctuated within each treatment and over time were not revealing. Intestinal IL-2 was highest in CP birds at 3 and 9 dpi, and lowest in A- birds at 3, 9, and 12 dpi (P < 0.05); no difference between treatments was found at 6 dpi (P > 0.05). Eimeria-specific intestinal Ab level was constant (P > 0.05) in C- birds, but increased with time (P < 0.05) in A-, AP and CP birds. Serum Ab levels were also constant in A- and CP, but increased (P < 0.05) in C- and AP after 6 dpi. The data demonstrate for the first time a probiotic-enhanced immunity in vitamin A-deficient birds. It is also the first study to demonstrate the probiotic effect on local cell-mediated immunity of chickens, best manifested by apparent lower intestinal invasion and development by EA, based on higher IL-2 secretion and lower EA oocyst production.