Mitigation Potential of Herbal Extracts and Constituent Bioactive Compounds on Salmonella in Meat-Type Poultry.

Herbal extracts have been widely evaluated in poultry production for their beneficial effects and potential substitute for antibiotics, which contribute to AMR and risks to human health through the consumption of infected meat. Salmonellosis is a systemic infection caused by Salmonella, an intracellular bacterium with the ability to cause systemic infections with significant implications for both the health and safety of farmers and consumers. The excessive use of antibiotics has escalated the incidence of antibiotic resistance bacteria in the poultry and livestock industry, highlighting the urgent need for alternatives especially in meat-type poultry. Both in vivo usage and in vitro studies of bioactive compounds from herbal extracts have demonstrated the effective antimicrobial activities against pathogenic bacteria, showing promise in managing Salmonella infections and enhancing poultry performance. Phytobiotic feed additives have shown promising results in improving poultry output due to their pharmacological properties, such as stimulating consumption, and enhancing antioxidant properties and preventing the increasing antimicrobial resistance threats. Despite potential for synergistic effects from plant-derived compounds, a further investigation into is essential to fully understand their role and mechanisms of action, for developing effective delivery systems, and for assessing environmental sustainability in controlling Salmonella in poultry production.

Supplementation of ginger root extract into broiler chicken diet: effects on growth performance and immunocompetence.

Ginger contains bioactive compounds that possess anti-inflammatory and antimicrobial properties. In this study, 432-day-old Ross 708 broiler male chicks were randomly allocated to 6 dietary treatments to investigate the effect of ginger root extract (GRE) on immunocompetence and growth performance to 6 wk of age. Treatment 1 (CON) consisted of chicks fed a corn-soybean meal (SBM), a base diet without GRE. Treatment 2 (MX) chicks were given basal diets containing bacitracin methylene disalicylate (BMD) at 0.055 g/kg. Treatments 3 (GRE-0.375%), 4 (GRE-0.75%), 5 (GRE-1.5%), and 6 (GRE-3%) were fed similar diet to control with GRE supplemented at 0.375%, 0.75%, 1.5%, and 3%, respectively. Moreover, HPLC analysis of GRE was carried out to determine the concentration of bioactive compounds found in GRE. Each treatment consisted of 6 replicate pens with 12 chicks/pen. Bodyweight (BW) and feed conversion ratio (FCR) were recorded. Results show that the concentration of bioactive compounds increased with increasing GRE supplementation. Likewise, dietary GRE supplementation did not have any detrimental effect on growth performance parameters up to 1.5%, as values for BWG was not different from CON and MX; however, 3% GRE had the poorest FCR and a lower BWG as compared to other treatments. On d 27 and d 41, fecal and cecal concentrations of total bacteria count (TBC), Escherichia coli, Lactobacillus spp., and Bifidobacterium spp enumerated using selective plating media showed that GRE supplementation significantly reduced (P < 0.05) the amount of TBC and E. coli but increased the number of beneficial microorganisms such as Lactobacillus spp. and Bifidobacterium spp. On d 20, no significant differences were observed (P > 0.05) among all treatments for antibody titer against Newcastle disease virus and total IgY antibodies; however, on d 27, GRE-0.75% had the highest value for both immune indicators and was not different from MX. Dietary supplementation of GRE up to 1.5% enhanced the immune system and suppressed E. coli while promoting the growth of healthy bacteria, without any detrimental effect on growth performance.

Characterization of intestinal immune response to Clostridium perfringens infection in broiler chickens.

Necrotic enteritis toxin B (NetB)-producing Clostridium perfringens (CP) type A is the etiological agent of necrotic enteritis (NE) - an economically significant disease in broiler chickens. Understanding the immune response to CP infection in broiler chickens is becoming important to develop effective vaccines against NE. An experiment was conducted to determine the expression levels of selected cytokine genes in the intestine and cecal tonsil of CP-challenged broiler chickens. In a floor-pen housing, broiler chickens were randomly assigned to the following treatment groups: 1) bacitracin methylene disalicylate (BMD)-free control diet with no CP challenge (CX), 2) BMD-supplemented diet with no CP challenge (CM), 3) BMD-free control diet with CP challenge (PCX), or 4) BMD-supplemented diet with CP challenge (PCM). The establishment of CP infection was confirmed, with the treatment groups exposed to CP having a 1.5 to 2-fold higher CP levels (P < 0.05) compared to the non-exposed groups. On day 1 and 7 post-challenge, jejunal segments and cecal tonsils were collected from experimental chickens for quantitative real-time RT-PCR analysis to determine the expression levels of interleukin (IL)-1ß, interferon-γ (IFN-γ), IL-2, IL-13, IL-17, IL-10, and transforming growth factor (TGF)-ß genes. Levels of antibodies to CP recombinant proteins were also determined in the plasma of experimental chickens. Results indicated that on day 7 post-challenge, IL-1ß (proinflammatory cytokine), IL-13 (Th2 cytokine), and IL-17 (Th17 cytokine) were upregulated (P < 0.05) in CP-challenged PCX and PCM treatments, compared to the unchallenged (control) CX and CM treatments. A reverse trend was observed for TGF-ß (anti-inflammatory cytokine), while no change was observed in IFN-γ (Th1 cytokine). Levels of plasma antibodies (IgY) to CP recombinant proteins were higher in CP-challenged treatments (PCX and PCM; P < 0.05), compared to their corresponding controls (CX and CM). It was concluded that CP infection induced inflammatory response in the intestine of broiler chickens, and the mechanisms of inflammation are probably mediated via Th2 and Th17 cells.

Effect of Clostridium perfringens infection and antibiotic administration on microbiota in the small intestine of broiler chickens.

The etiological agent of necrotic enteritis (NE) is Clostridium perfringens (CP), which is an economically significant problem for broiler chicken producers worldwide. Traditional use of in-feed antibiotic growth promoters to control NE disease have resulted in the emergence of antibiotic resistance in CP strains. Identification of probiotic bacteria strains as an alternative to antibiotics for the control of intestinal CP colonization is crucial. Two experiments were conducted to determine changes in intestinal bacterial assemblages in response to CP infection and in-feed bacitracin methylene disalicylate (BMD) in broiler chickens. In each experiment conducted in battery-cage or floor-pen housing, chicks were randomly assigned to the following treatment groups: 1) BMD-supplemented diet with no CP challenge (CM), 2) BMD-free control diet with no CP challenge (CX), 3) BMD-supplemented diet with CP challenge (PCM), or 4) BMD-free control diet with CP challenge (PCX). The establishment of CP infection was confirmed, with the treatment groups exposed to CP having a 1.5- to 2-fold higher CP levels (P < 0.05) compared to the non-exposed groups. Next-generation sequencing of PCR amplified 16S rRNA genes, was used to perform intestinal bacterial diversity analyses pre-challenge, and at 1, 7, and 21 d post-challenge. The results indicated that the intestinal bacterial assemblage was dominated by members of the phylum Firmicutes in all treatments before and after CP challenge, especially the Lactobacillaceae and Clostridiales families. In addition, we observed post-challenge emergence of members of the Enterobacteriaceae and Streptococcaceae in the non-medicated PCX treatment, and emergence of the Enterococcaceae in the medicated PCM treatment. This study highlights the bacterial interactions that could be important in suppressing or eliminating CP infection within the chicken intestine. Future studies should explore the potential to use commensal strains of unknown Clostridiales, Lactobacillaceae, Enterobacteriaceae, Streptococcaceae, and Enterococcaceae in effective probiotic formulations for the control of CP and NE disease.