Impacts of Eimeria coinfection on growth performance, intestinal health and immune responses of broiler chickens

Mechanisms of the effects of turpiniae folium extract on growth performance, immunity, antioxidant activity and intestinal barrier function in LPS-challenged broilers

Turpiniae folium extract (TFE) has shown anti-inflammatory and immunomodulatory effects in broilers. However, its mechanisms remain unclear. The aim of this study is to investigate the underlying mechanisms by which TFE influences growth performance, jejunal morphology, immune function, antioxidant capacity and barrier integrity in broilers challenged with Lipopolysaccharide (LPS). A total of 240 one-day-old female broilers were randomly divided into four groups with six replicates of ten birds each. A 2 × 2 factorial design with TFE (basal diets supplemented with 0 or 500 mg/kg TFE) and LPS challenge (intraperitoneal injection of 1 mg/kg body weight of sterile saline or LPS at 21, 23 and 25 days of age). The trial lasted for 26 days. The results showed that: Prior to the LPS challenge, dietary supplementation with TFE for 21 days increased both average daily gain (ADG) (P = 0.037) and average daily feed intake (ADFI) (P = 0.045) in broilers. During the LPS challenge period, LPS challenge led to a decline in growth performance and a negative impact on intestinal morphology, while TFE supplementation significantly reversed these adverse effects, as evidenced by increases in ADG (P = 0.004), ADFI (P = 0.046), jejunal villus height (VH) (P = 0.035), the villus height to crypt depth ratio (VH/CD) (P = 0.007) and decreases in the feed-to-gain ratio (F/G) (P = 0.025), jejunal crypt depth (CD) (P = 0.049). LPS induced inflammatory responses and oxidative stress in the jejunum, leading to a significant upregulation of pro-inflammatory factor gene and protein expression, and a marked downregulation of anti-inflammatory and antioxidant gene and protein expression. TFE supplementation mitigated these effects by yielding completely opposite results except for the expression of toll-like receptor 4 (TLR4) protein (P = 0.916). LPS negatively regulates the expression of genes and proteins involved in intestinal mucosal barrier function. In contrast, TFE supplementation significantly upregulated the expression of zonula occludens-1 (ZO-1) (P < 0.001) gene and ZO-1 (P < 0.001), occludin (OCLN) (P < 0.001), claudin (CLDN) (P < 0.001) proteins. In conclusion, dietary supplementation with TFE effectively counteracts the intestinal immune and oxidative stress induced by LPS challenge in broilers, improves intestinal mucosal barrier integrity and tissue morphology, and ultimately mitigates the negative impact of LPS on broiler growth performance. This effect may involve the modulation of the Nrf2 and nuclear factor kappa B (NF-κB) signaling pathways.

Matrine disturbs the eimeria necatrix-induced loop of tuft cell-intestinal stem cell-goblet cell by inactivating IL-13/JAK2/STAT3 signaling

As sensors in the gut, tuft cells integrate a complex array of luminal signals to regulate the differentiation fate of intestinal stem cells (ISCs), which trigger a loop of tuft cell-ISC-goblet cell after parasitic infection. As a plant-derived alkaloid, Matrine plays a prominent role for standardizing ISC functions in Eimeria necatrix (EN)-exposed chicks. In this study, we investigated the modulation effects of Matrine on the specific intestinal epithelial cell loop in EN-exposed chicks in vivo and intestinal organoids (IOs) ex vivo. The results showed that EN infection resulted in swelling and hemorrhage of the jejunum, accompanied by the increase in levels of sIgA and inflammatory cytokines (IL-6, IL-1β, and TNF-α). And these inflammatory symptoms were effectively relieved by Matrine intervention. Concurrently, Matrine resisted the EN-induced increase in tuft cell numbers and levels of crucial pro-inflammatory factors (IL-25 and IL-13), while also reversing the differentiation of secretory cell progenitors into goblet cells. Importantly, Matrine impeded the upregulation of the inflammatory signaling pathway JAK2/STAT3 in EN-infected chicks and IOs. Conversely, exogenous supplementation of IL-13 or activation of STAT3 via Colivelin eliminated the standardization of the tuft cell-ISC-goblet cell loop by Matrine. Overall, our findings suggested that Matrine intercepted the tuft cell-ISC-goblet cell loop by reinstating IL-13/JAK2/STAT3 signaling after EN infection.

Innovative prevention and control of coccidiosis: targeting sporogony for new control agent development

Coccidiosis is one of the most significant diseases affecting the poultry industry, with recent estimates indicating that it causes annual losses exceeding £10 billion globally. Increasing concerns over drug residues and resistance have elevated the importance of safe and effective vaccines as the primary method for controlling coccidiosis and other animal diseases. However, current commercial live vaccines for coccidiosis can negatively impact the feed conversion rates of young broilers and induce subclinical symptoms of coccidiosis, limiting their widespread adoption. Eimeria species, the causative agents of coccidiosis, exhibit unique biological characteristics. Their life cycle involves 2 or more generations of schizogony and 1 generation of gametogony within the host, followed by sporogony in a suitable external environment. Sporogony is crucial for Eimeria oocysts to become infectious and propagate within the host. Focusing on the sporogony process of Eimeria presents a promising approach to overcoming technical challenges in the efficient control of coccidiosis, addressing the urgent need for sustainable and healthy farming practices. This paper systematically reviews existing control strategies for coccidiosis, identifies current challenges, and emphasizes the research progress and future directions in developing control agents targeting sporogony. The goal is to provide guidance for the formulation of scientific prevention and control measures for coccidiosis.

Expression profile of Toll-like receptors and cytokines in the cecal tonsil of chickens challenged with Eimeria tenella

Chicken coccidiosis, caused by Eimeria spp., seriously affects the development of the poultry breeding industry. Currently, extensive studies of chicken coccidiosis are mostly focused on acquired immune responses, while information about the innate immune response of chicken coccidiosis is lacking. Toll-like receptor (TLR), the key molecule of the innate immune response, connects innate and adaptive immune responses and induces an immune response against various pathogen infections. Therefore, the quantitative real-time PCR was used to characterize the expression profile of chicken TLRs (chTLRs) and associated cytokines in the cecal tonsil of chickens infected with Eimeria tenella. The results showed that the expression of chTLR1a, chTLR2a, and chTLR5 was significantly upregulated at 3 h post-infection, while chTLR1b, chTLR2b, chTLR3, chTLR7, chTLR15 and chTLR21 was significantly downregulated (p < 0.05). In addition, chTLR1a expression rapidly reached the peaked expression at 3 h post-infection, while chTLR2b and chTLR15 peaked at 168 h post-infection, and chTLR2a expression was highest among chTLRs, peaking at 48 h post-infection (p < 0.05). For cytokines, interleukin (IL)-6 and tumor necrosis factor (TNF)-α peaked at 96 h post-infection, IL-4 and IL-12 peaked at 144 h post-infection, and interferon-γ expression was highest among cytokines at 120 h post-infection. In addition, IL-12 and IL-17 were markedly upregulated at 6 h post-infection (p < 0.05). These results provide insight into innate immune molecules during E. tenella infection in chickens and suggest that innate immune responses may mediate resistance to chicken coccidiosis.

Dietary advanced chelate technology-based 7-mineral supplement improves growth performance and intestinal health indicators during a mixed Eimeria challenge in broiler chickens

The health and productivity of broilers may be improved by optimizing the availability and levels of trace minerals (TM) in their feed, especially in the presence of parasites. This study investigated the effects of replacing inorganic TM (ITM) with an advanced chelate technology-based 7 TM (ACTM) on performance, hematology, lesion score, oocyst shedding, gut morphology, and tight junction structure in broilers challenged with mixed Eimeria species. There were 480 1-day-old broiler chickens divided into 5 groups: uninfected negative control and recommended levels of ITM (NC); infected positive control and recommended levels of ITM (PC); or PC supplemented with salinomycin (SAL); PC diet with 50 % ACTM instead of ITM (ACTM50); or PC diet with 100 % ACTM instead of ITM (ACTM100). All groups, except NC, were orally challenged with mixed Eimeria spp. oocysts on day 14. Each group had 6 replicate cages, with 16 birds per replicate. The results showed that the NC, SAL, and ACTM100 groups had higher (P < 0.05) body weight, average daily gain (ADG), and European production efficiency index (EPEI), as well as a lower (P < 0.05) feed conversion, mortality rate, and heterophile to lymphocyte ratio compared to the PC group, with the NC group having the highest ADG and EPEI throughout the experiment. The SAL and ACTM100 groups had lower (P < 0.05) intestinal lesion scores and oocyst numbers compared to the PC group, although all coccidiosis-challenged groups had higher oocyst shedding compared to the NC group. On day 24, the challenged birds in the SAL and ACTM100 groups had higher (P < 0.05) villus height and surface area in the duodenum and ileum, as well as a higher (P < 0.05) villus height to crypt depth ratio in the jejunum. The expression levels of jejunal CLDN1 and ZO-1 were also higher (P < 0.05) in the ACTM100 and SAL groups compared to the PC and ACTM50 groups at 24 days of age. In conclusion, while using ACTM in broiler diets at 50 % of the commercial recommended levels maintained performance and physiological responses, complete replacement with ACTM improved growth performance and intestinal health characteristics, similar to salinomycin under Eimeria challenge conditions.

Molecular phylogenetic analysis and seasonal dynamics of Eimeria species infecting broilers of Kashmir, India

Globally, the poultry industry is seriously threatened by coccidiosis caused by various species of Eimeria. This protozoan parasite inhabits the epithelial lining of the gastrointestinal tract of poultry globally and can cause serious clinical disease. The present study was carried out on poultry farms located in various regions of Kashmir, India, to investigate the prevalence and phylogenetic relationships of Eimeria species affecting broiler chickens. Over a period of one year, fecal samples were collected from 60 poultry farms in Kashmir and morphological and molecular techniques were employed for Eimeria species identification. Results revealed a high prevalence of coccidiosis, with 58.3% (35/60) of farms positive for Eimeria. The most prevalent species were E. tenella (31/35, 88.6%) followed by E. acervulina (25/35, 71.4%), E. maxima (19/35, 54.3%), E. mitis (18/35, 51.4%), and E. necatrix (9/35, 25.7%). Seasonal variation in prevalence was also observed, with the highest rates in autumn (86.7%) and summer (66.7%). Additionally, younger birds (3-4 weeks) exhibited higher infection rates (85.7%) compared to older birds (57.9%) (5-6 weeks). Mixed infection was found in 94.2% (33/35) of positive farms. Phylogenetic analysis using ITS1 sequences confirmed species clustering and revealed evolutionary relationships among Eimeria species. E. tenella and E. necatrix formed a distinct clade, while E. acervulina formed another. The study underscores the importance of molecular techniques in accurate species identification and provides valuable insights into the epidemiology of coccidiosis in poultry in Kashmir. Effective control strategies, including vaccination and improved management practices, are necessary to mitigate the economic losses associated with this widespread poultry disease.

Silymarin effectively prevents and treats Eimeria tenella infection in chicks

Silymarin, a botanical medicine derived from milk thistle seeds and is known to improve chicken growth and gut health when added to the feed. However, its role in the prevention and treatment of chicken coccidiosis remains unclear. This study investigated the efficacy of various doses of silymarin in preventing and treating Eimeria tenella infection in chicks. A total of 180 one-day-old specific pathogen-free chicks were randomized into six groups of 30 chicks each, no treatment (NC group); E. tenella infection (CC group); diclazuril medication during d 14 to 21 and E. tenella infection (DC group); and three groups infected with E. tenella and administered low, medium, or high doses of silymarin during d 12 to 21. All groups except NC were infected with E. tenella on d 14, with indicators observed on d 21. The growth performance was higher in the silymarin treated groups than that in the CC group, and the oocyst count per gram of manure, blood stool, and cecal lesion scores decreased. The medium-dose silymarin group exhibited the best treatment effect. Additionally, the silymarin groups displayed improved histological, morphology, and intestinal barrier integrity. The amounts of proinflammatory factors and harmful bacteria in the cecum were also reduced. Additionally, the activity of serum and cecal antioxidant enzymes, as well as the abundance of beneficial gut microbiota, increased in the cecum. In conclusion, this study demonstrated that silymarin can prevent and treat E. tenella infections. These data provide a scientific and conceptual basis for the development of a botanical dietary supplement from silymarin for the treatment and control of coccidiosis in chicks.

Metabarcoding of protozoa and helminth in black-necked cranes: a high prevalence of parasites and free-living amoebae

Parasites and free-living amoebae (FLA) are common pathogens that pose threats to wildlife and humans. The black-necked crane (Grus nigricollis) is a near-threatened species and there is a shortage of research on its parasite diversity. Our study aimed to use noninvasive methods to detect intestinal parasites and pathogenic FLA in G. nigricollis using high-throughput sequencing (HTS) based on the 18S rDNA V9 region. A total of 38 fresh fecal samples were collected in Dashanbao, China, during the overwintering period (early-, middle I-, middle II-, and late-winter). Based on the 18S data, eight genera of parasites were identified, including three protozoan parasites: Eimeria sp. (92.1%) was the dominant parasite, followed by Tetratrichomonas sp. (36.8%) and Theileria sp. (2.6%). Five genera of helminths were found: Echinostoma sp. (100%), Posthodiplostomum sp. (50.0%), Euryhelmis sp. (26.3%), Eucoleus sp. (50.0%), and Halomonhystera sp. (2.6%). Additionally, eight genera of FLA were detected, including the known pathogens Acanthamoeba spp. (n = 13) and Allovahlkampfia spp. (n = 3). Specific PCRs were used to further identify the species of some parasites and FLA. Furthermore, the 18S data indicated significant changes in the relative abundance and genus diversity of the protozoan parasites and FLA among the four periods. These results underscore the importance of long-term monitoring of pathogens in black-necked cranes to protect this near-endangered species.

Comparison of necrotic enteritis effects on growth performance and intestinal health in two different meat-type chicken strains Athens Canadian Random Bred and Cobb 500

Chickens have undergone genetic improvements in the past few decades to maximize growth efficiency. However, necrotic enteritis (NE), an enteric disease primarily caused by C. perfringens, remains a significant problem in poultry production. A study investigated the differences in intestinal health between the nonselected meat-type chicken Athens Canadian Random Bred (ACRB) and the modern meat-type Cobb 500 broilers (Cobb) when challenged with experimental NE. The study utilized a 2 × 3 factorial arrangement, consisting of two main effects of chicken strain and NE challenge model (nonchallenged control, NC; NE challenge with 2,500/12,500 Eimeria maxima oocysts + 1 × 109C. perfringens, NE2.5/NE12.5). A total of 432 fourteen-day-old male ACRB and Cobb were used until 22 d (8 d postinoculation with E. maxima on d 14, dpi), and the chickens were euthanized on 6 and 8 dpi for the analysis. All data were statistically analyzed using a two-way ANOVA, and Student's t-test or Tukey's HSD test was applied when P < 0.05. The NE12.5 group showed significant decreases in growth performance and relative growth performance from d 14 to 20, regardless of chicken strain (P < 0.01). The ACRB group exhibited significant decreases in relative body weight and relative body weight gain compared to the Cobb group from d 14 to 22 (P < 0.01). On 6 and 8 dpi, both NE challenge groups showed significant decreases in intestinal villus height to crypt depth ratio, jejunal goblet cell count, and jejunal MUC2 and LEAP2 expression (P < 0.01). Additionally, the NE12.5 group had significantly higher intestinal NE lesion score, intestinal permeability, fecal E. maxima oocyst count, intestinal C. perfringens count, and jejunal IFNγ and CCL4 expression compared to the NC group (P < 0.05). In conclusion, NE negatively impacts growth performance and intestinal health in broilers, parameters regardless of the strain.

Coinfection of the gut with protozoal and metazoal parasites in broiler and laying chickens

The chicken business faces substantial economic losses due to the risk of parasitic coinfection. Because the current study aimed to investigate enteric parasitic coinfections problems among the suspected examined chicken farms, samples were collected during the field investigation from suspected freshly dead birds, clinically diseased, apparently healthy, and litter samples for further laboratory parasitological, histopathological, and immunological examinations. Variable mortalities with various clinical indicators, such as ruffled feathers, weight loss, diarrhea of various colors, and a decline in egg production, occurred on the farms under investigation. In addition, the treatment protocols of each of the farms that were evaluated were documented and the m-RNA levels of some cytokines and apoptotic genes among the infected poultry have been assessed. The prevalence rate of parasitic coinfection in the current study was found to be 8/120 (6.66%). Parasitological analysis of the samples revealed that they belonged to distinct species of Eimeria, cestodes, and Ascaridia galli. When deposited, A. galli eggs were nonembryonated and ellipsoidal, but cestodes eggs possessed a thin, translucent membrane that was subspherical. Eimeria spp. oocysts in layer chickens were identified as Eimeria acervulina and Eimeria maxima in broiler chickens. Our findings proved that coinfection significantly upregulated the IL-1β, BAX, and Cas-3 genes. Conversely, the IL-10, BCL-2, and AKT mRNA levels were downregulated, indicating that nematode triggered apoptosis. The existence of parasite coinfection was verified by histological investigation of the various intestinal segments obtained from affected flocks. A. galli and cestodes obstructed the intestinal lumen, causing different histological alternations in the intestinal mucosa. Additionally, the lamina propria revealed different developmental stages of Eimeria spp. It was determined that parasite coinfection poses a significant risk to the poultry industry. It was recommended that stringent sanitary measures management methods, together with appropriate treatment and preventative procedures, be employed in order to resolve such issues.

Protective Efficacy Induced by the Common Eimeria Antigen Elongation Factor 2 against Challenge with Three Eimeria Species in Chickens

Avian coccidiosis arises from co-infection involving multiple Eimeria species, which could give rise to substantial economic losses in the global poultry industry. As a result, multivalent anticoccidial vaccines containing common Eimeria antigens offer considerable promise for controlling co-infection in clinical practice. In our previous study, Elongation factor 2 (EF2) was deemed as an immunogenic common antigen across various Eimeria species. This current investigation aimed to further assess the immunogenicity and protective efficacy of EF2 in recombinant subunit vaccine format against three Eimeria species. The EF2 gene cloned from Eimeria maxima (E. maxima) cDNA was designated as EF2 of E. maxima (EmEF2). The immunogenicity of the recombinant protein EmEF2 (rEmEF2) was assessed through Western blot analysis. The evaluation of the vaccine-induced immune response encompassed the determination of T lymphocyte subset proportions, cytokine mRNA transcription levels, and specific IgY concentrations in rEmEF2-vaccinated chickens using flow cytometry, quantitative real-time PCR (qPCR), and indirect enzyme-linked immunosorbent assay (ELISA). Subsequently, the protective efficacy of rEmEF2 was evaluated through vaccination and challenge experiments. The findings demonstrated that rEmEF2 was effectively recognized by the His-tag monoclonal antibody and E. maxima chicken antiserum. Vaccination with rEmEF2 increased the proportions of CD4+ and CD8+ T lymphocytes, elevated IL-4 and IFN-γ mRNA transcription levels, and enhanced IgY antibody levels compared to the control groups. Moreover, compared to the control groups, vaccination with rEmEF2 led to decreased weight loss, reduced oocyst outputs, and alleviated enteric lesions. Furthermore, in the rEmEF2-immunized groups, challenges with E. maxima and E. acervulina resulted in anticoccidial index (ACI) scores of 166.35 and 185.08, showing moderate-to-excellent protective efficacy. Nevertheless, challenges with E. tenella and mixed Eimeria resulted in ACI scores of 144.01 and 127.94, showing low protective efficacy. In conclusion, EmEF2, a common antigen across Eimeria species, demonstrated the capacity to induce a significant cellular and humoral immune response, as well as partial protection against E. maxima, E. acervulina, and E. tenella. These results highlight EmEF2 as a promising candidate antigen for the development of multivalent vaccines targeting mixed infections by Eimeria species.