Induction of local protective immunity to Eimeria acervulina by a Lactobacillus-based probiotic.

Previously we have shown that resistance to Eimeria acervulina (EA) infection in broiler chickens was enhanced by a probiotic treatment. In the present studies, we examined cytokine and oocyst production under similar conditions using a commercial Lactobacillus-based probiotic. Day-old male broiler chicks were fed control or probiotic diets and were orally challenged with either 2x10(4) (Experiment 1) or 1x10(4) (Experiment 2) oocysts of EA at 3 weeks of age. For the first experiment, fecal oocyst shedding and IFN-gamma levels in the culture supernatants of ConA-stimulated spleen lymphocytes were evaluated. Humoral and local cell-mediated immunity in the second experiment were assessed by evaluating antibody and cytokine (IFN-gamma and IL-2) levels in sera and intestinal secretions on a 3-day interval post inoculation. Results showed small but significant (P<0.05) differences in cytokine levels and oocyst production but not antibody levels between the probiotic-treated and control groups. Collectively, these data suggest a positive impact of the probiotic on cellular immune responses of infected broilers as compared to control chickens resulting in enhanced resistance to EA as shown in reduced fecal oocyst shedding. The results showed an immunoregulatory effect of probiotic diets on the local cell-mediated immunity in poultry and provide a rationale for further study to investigate the beneficial effects of Lactobacillus-based probiotics in food animals.

Intestinal immunomodulation by vitamin A deficiency and lactobacillus-based probiotic in Eimeria acervulina-infected broiler chickens.

In a 2 X 2 factorial study, a broiler starter ration was amended for vitamin A (control, C; deficient, A) and probiotic status (-, P) to investigate their modulatory effects onthe host immune system. Birds were inoculated orally with Eimeria acervulina (EA) oocysts, and disease susceptibility was evaluated by assessment of fecal oocyst shedding. Humoral and local cellular mediated immunity were assessed by evaluation of antibody and cytokine (interferon-gamma [IFN-gamma] and interleukin-2 [IL-2]) levels in sera and intestinal secretions on a 3-day interval after inoculation. Fecal oocyst shedding was highest (P < 0.05) in A- birds, followed by AP, C-, and CP birds. 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 days postinfection (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 antibody (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 birds but increased (P < 0.05) in C- and AP birds after 6 DPI. The data demonstrate for the first time a probiotic-enhanced immunity in vitamin A deficient birds. This study is also the first to demonstrate the probiotic effect on local cell-mediated immunity of chickens, best manifested by apparent lower intestinal invasion and development by EA, on the basis of higher IL-2 secretion and lower EA oocyst production.

High-performance liquid chromatographic determination of biogenic amines in poultry carcasses.

Biogenic amines, produced by bacterial decarboxylation of amino acids, have been associated with toxicological symptoms in broilers fed various poultry byproducts. A reversed-phase high-performance liquid chromatographic method is described for the quantitation of eight biogenic amines (tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine) in chicken carcasses. Amines were extracted with perchloric acid, derivatized with dansyl chloride, separated using gradient elution (methanol and water), and detected by fluorescence. Benzylamine was used as the internal standard. Linearity, repeatability, and recovery of the method were evaluated. The method was linear for all of the amines studied at concentrations ranging from 0.05 to 25 microg/mL. Average recoveries ranged from 92.6% to 96.8% for all amines except for histamine, which was 74.6%.