Effects of Eimeria tenella Infection on Key Parameters for Feed Efficiency in Broiler Chickens

Coccidiosis in Egg-Laying Hens and Potential Nutritional Strategies to Modulate Performance, Gut Health, and Immune Response

Avian coccidiosis, despite advancements in management, nutrition, genetics, and immunology, still remains the most impactful disease, imposing substantial economic losses to the poultry industry. Coccidiosis may strike any avian species, and it may be mild to severe, depending on the pathogenicity of Eimeria spp. and the number of oocysts ingested by the bird. Unlike broilers, low emphasis has been given to laying hens. Coccidiosis in laying hens damages the gastrointestinal tract and causes physiological changes, including oxidative stress, immunosuppression, and inflammatory changes, leading to reduced feed intake and a drastic drop in egg production. Several countries around the world have large numbers of hens raised in cage-free/free-range facilities, and coccidiosis has already become one of the many problems that producers have to face in the future. However, limited research has been conducted on egg-laying hens, and our understanding of the physiological changes following coccidiosis in hens relies heavily on studies conducted on broilers. The aim of this review is to summarize the effect of coccidiosis in laying hens to an extent and correlate it with the physiological changes that occur in broilers following coccidiosis. Additionally, this review tries to explore the nutritional strategies successfully used in broilers to mitigate the negative effects of coccidiosis in improving the gut health and performance of broilers and if they can be used in laying hens.

Impacts of varying methionine to cysteine supplementation ratios on growth performance, oxidative status, intestinal health, and gene expression of immune response and methionine metabolism in broilers under Eimeria spp. challenge

A study was conducted to investigate effects of different methionine (Met) to cysteine (Cys) supplementation ratios (MCR) on growth performance, oxidative status, intestinal health, immune responses, and methionine metabolism in broilers under Eimeria challenge. A total of 720 male Cobb500 broilers (14-day-old) were allocated in a 2 × 5 factorial arrangement (5 diets, with or without challenge) with 6 replicates per treatment. The total sulfur amino acid concentrations were consistent across treatments meeting the breeder's recommendation, only MCR varied. The diets were labeled as MET100; MET75; MET50; MET25; and MET0, representing MCR of 100:0; 75:25; 50:50; 25:75; and 0:100, respectively. Data were analyzed by 2-way ANOVA and orthogonal polynomial contrast. Growth performance declined linearly or quadratically as MCR decreased (P < 0.01). On 6-day postinoculation (DPI), interaction effects (P < 0.01) were found; BW and body weight gain were lower in MET0 compared to the other treatments in the nonchallenged groups, whereas not in the challenged groups. On 6 and 9 DPI, serum total antioxidant capacity linearly decreased as MCR decreased (P < 0.05). Hepatic activities of glutathione peroxidase on 6 DPI and superoxide dismutase on 9 DPI changed quadratically as MCR decreased (P < 0.05). The digestibility of Met linearly decreased whereas the digestibility of Cys linearly increased as MCR decreased. The ileal crypt depth linearly decreased as MCR decreased (P < 0.01) on 6 DPI. The expression of transforming growth factor beta on 6 and 9 DPI, tumor necrotic factor alpha and interleukin 10 on 9 DPI changed quadratically as MCR decreased (P < 0.05). Eimeria challenge increased expression of Met adenosyltransferase and cystathionine gamma-lyase, whereas decreasing the expression of other Met metabolism genes (P < 0.01) on 6 DPI. Expression of Met metabolism genes linearly increased as MCR decreased (P < 0.05). In conclusion, different Met to Cys supplementation ratios exerted linearly or quadratically effects on the growth performance, oxidative status, intestinal health, and metabolism of Met in broiler chickens under Eimeria infection.

Effects of 25-hydroxycholecalciferol on performance, gut health, and bone quality of broilers fed with reduced calcium and phosphorus diet during Eimeria challenge

This study evaluated the effects of 25-hydroxycholecalciferol (25-OHD) on performance, gut health, and bone quality of broilers fed with reduced calcium (Ca) and phosphorus (P) diet during Eimeria spp. challenge. A total of 576 fourteen-day-old Cobb 500 male chicks were randomly distributed in a 2 × 2 × 2 factorial arrangement, with 6 replicates of 12 birds each. The main factors were 25-OHD level (0 or 3,000 IU/kg of feed), mineral level (0.84% of Ca/0.42% of P, the levels recommended for the grower phase (NOR) or 0.64% of Ca/0.22% of P (RED), and mid-high mixed Eimeria challenge or nonchallenge. 25-OHD improved phosphorus retention (P = 0.019), bone ash weight (P = 0.04), cortical bone trabecular connectivity (P = 0.043) during coccidiosis. For birds fed with reduced mineral levels, 25-OHD supplementation increased bone ash weight (P = 0.04). However, 25-OHD did not improve bone ash weight when birds were challenged and fed with reduced mineral levels. The dietary 3,000 IU of 25-OHD supplementation did not improve performance or gut morphology but support bone health during coccidiosis. Future investigations are needed for better understand 25-OHD role on bone microarchitecture and oxidative metabolism during coccidiosis.

Phylogenetic analysis of Eimeria tenella isolates from chicken of sub-tropical mountains of Meghalaya, India

BACKGROUND

Coccidiosis is the most common and pathogenic intestinal disease caused by different species of Eimeria is chicken. In this study, we describe the prevalence, molecular diagnosis and evolutionary insight of Eimeria tenella in chicken of Meghalaya's sub-tropical mountainous area.

METHODS AND RESULTS

Faecal samples (337 no.) and dead chicks (298 no.) were collected every month from January to July' 2023 from poultry farms (4nos.) in and around Umiam, Ri-Bhoi, Meghalaya. The chicks were categorized into different age groups viz. < 3, 3-6 and > 6 weeks. Samples were examined by flotation techniques and post-mortem. The oocysts were sporulated in 2.5% potassium dichromate solution. Eimeria tenella's 18 S rRNA gene genomic DNA was extracted, amplified, and sequenced. Fecal sample and postmortem examinations revealed 24.04% and 33.22% infections of Eimeria sp., respectively. Oocyst per gram (OPG) was recorded highest and lowest in July (26,500) and February (9800), respectively. Amplification of the 18 S rRNA small subunit gene (SSU) by Polymerase Chain Reaction (PCR) revealed a 1790 bp band size. The amplicon was sequenced and deposited in the NCBI database. BLAST analyses of the SSU rRNA gene of E. tenella, Umiam, Meghalaya isolate (OR458392.1) revealed sequence similarities of more than 99% with SSU rRNA gene sequences available in the NCBI database. Pair wise alignment exhibited nucleotide homology ranging from 71.59 to 100.0% with the maximum sequence homology (100.0%) shared with the E. tenella isolate from Turkey (HQ680474.1) and the lowest homology of 95.6% with UK (HG994972.1). Umiam isolate were found to have 97.08% and 100.0% nucleotide similarities with E. tenella from both the UK (AF026388.1) and the USA (U40264.1), respectively. However, nucleotide similarities of 98.24%, 85.33%, 84.75% and 81.35% were observed with E. tenella strain Bangalore (JX312808.1), E. tenella isolate Kerala-1 (JX093898.1), E. tenella isolate Kerala-3 (JX093900.1) and E. tenella isolate Kerala-2 (JX093899.1), respectively. Phylogenetic analysis of SSU rRNA sequences of E. tenella Umiam, Meghalaya isolate with cognate sequences throughout the world revealed these sequences are distinct but at the same time share a close phylogenetic relationship with Indian isolates from Bangalore and Andhra Pradesh. In addition, the distant phylogenetic relationship was observed with cognate gene sequences of United States of America, Canada, China.

CONCLUSION

Phylogenetic analysis of SSU rRNA sequences of E. tenella Umiam, Meghalaya isolate with cognate sequences throughout the world revealed these sequences are distinct but at the same time share a close phylogenetic relationship with Indian isolates from Bangalore and Andhra Pradesh. Distant phylogenetic relationship was observed with cognate gene sequences of United States of America, Canada, China.

Research Note: Effect of dietary xylo-oligosaccharide on growth performance, intestinal histomorphology, and specific cecal bacteria in broiler chickens

This study was conducted to evaluate the prebiotic effect of xylo-oligosaccharide (XOS) supplemented in a corn-soybean meal (SBM) based conventional diet on growth performance, intestinal histomorphology, and quantification of specific bacteria in the ceca of broilers. A total of 240 d of hatch Cobb 500 male broiler chicks were randomly assigned to 4 dietary treatments (corn-SBM-based control diet) containing 0, 0.05, 0.1, and 0.2% XOS. The broilers were raised for 21 d in 6 replicate cages, each containing 10 birds. Growth performance parameters were obtained weekly. Additionally, small intestinal tissues were collected to evaluate histomorphometry and whole ceca were collected to quantify bacterial populations on D21. The results showed that inclusion of XOS has similar body weight (BW), body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) as the control group during the 21-day study. The results further indicate a tendency for the jejunum villus to crypt ratio (VH:CD) to increase in birds given 0.05 and 0.2% XOS (P = 0.08). Cecal bacteria quantification showed a linear increase in Bifidobacterium with increasing XOS levels (P < 0.0001) and a decrease Clostridium perfringens levels compared to birds fed the control diet (P < 0.0001). However, there were no differences in the total counts of Lactobacillus and E. coli. Together these results showed that while there were no differences in growth parameters up to 21 d, the histomorphology findings and the increase in Bifidobacterium, along with the reduction in C. perfringens observed in the XOS groups, suggest a beneficial impact of XOS inclusion on gut health. Further research with longer feeding periods and higher XOS levels should be conducted to explore potential positive effects on both growth and gut health parameters.

Effects of xylanase, protease, and xylo-oligosaccharides on growth performance, nutrient utilization, short chain fatty acids, and microbiota in Eimeria-challenged broiler chickens fed high fiber diet

A 21-d experiment was conducted to study the effect of xylanase, protease, and xylo-oligosaccharides on growth performance, nutrient utilization, gene expression of nutrient transporters, cecal short-chain fatty acids (SCFA), and cecal microbiota profile of broilers challenged with mixed Eimeria spp. The study utilized 392 zero-d-old male broiler chicks allocated to 8 treatments in a 4 × 2 factorial arrangement, as follows: corn-soybean meal diet with no enzyme (Con); Con plus xylanase alone (XYL); Con plus xylanase combined with protease (XYL + PRO); or Con plus xylo-oligosaccharides (XOS); with or without Eimeria challenge. Diets were based on a high-fiber (100 g/kg soluble fibers and 14 g/kg insoluble fibers) basal diet. At d 15, birds in challenged treatment were gavaged with a solution containing Eimeria maxima, Eimeria acervulina, and Eimeria tenella oocysts. At d 21, birds were sampled. Eimeria depressed (P < 0.01) growth performance and nutrient utilization, whereas supplementation had no effect. There were significant Eimeria × supplementation interactions for the sugar transporters GLUT5 (P = 0.02), SGLT1 (P = 0.01), SGLT4 (P < 0.01), and peptide transporter PepT1 (P < 0.01) in jejunal mucosa. Eimeria challenge increased the expression of GM-CSF2 (P < 0.01) and IL-17 (P = 0.04) but decreased (P = 0.03) IL-1β expression in the cecal tonsil. Eimeria × supplementation interactions for cecal acetate, butyrate, and total SCFA showed that concentrations increased or tended to be greater in the supplemented treatments, but only in non-challenged birds. Birds challenged with Eimeria spp. had higher concentrations of isobutyrate (P < 0.01), isovalerate (P < 0.01), and valerate (P = 0.02) in cecal content. Eimeria challenge significantly (P < 0.01) decreased the microbial richness and diversity, and increased (P < 0.01) the proportion of Anaerostipes butyraticus, Bifidobacterium pseudolongum, and Lactobacillus pontis. In conclusion, Eimeria infection depressed growth performance, nutrient utilization with regulating nutrient transporters. Furthermore, Eimeria challenge shifted the microbial profile and reduced microbial richness and diversity. On the other hand, enzyme supplementation showed limited benefits, which included increased concentrations of SCFA.

Development of a new immunodiagnostic tool for poultry coccidiosis using an antigen-capture sandwich assay based on monoclonal antibodies detecting an immunodominant antigen of Eimeria

This study was conducted to develop an antigen-capture ELISA that detects an immunodominant antigen of Eimeria, 3-1E which is present in all Eimeria species, using a set of 3-1E-specific mouse monoclonal antibodies (mAbs). Highly sensitive 3-1E-specific antigen-capture ELISA was established using compatible mAb pairs (#318 and #320) selected from 6 mAbs (#312, #317, #318, #319, #320, and #323) with high binding activity against recombinant 3-1E protein. These anti-3-1E mAbs specifically recognized E. tenella sporozoites and a higher level of 3-1E was detected in the lysate of sporozoites than in sporocysts. Immunofluorescence assay (IFA) using 2 mAbs (#318 and #320) showed specific staining around the membrane of E. tenella sporozoites. In order to measure the changes in the 3-1E level during in coccidiosis, serum, feces, jejunal, and cecal contents were individually collected daily for 7-days postinfection (dpi) with E. maxima and E. tenella. The new ELISA was sensitive and specific for 3-1E detection in all samples collected daily from E. maxima- and E. tenella-infected chickens for a week, and the detection sensitivity ranges were 2 to 5 ng/mL and 1 to 5 ng/mL in serum, 4 to 25 ng/mL and 4 to 30 ng/mL in feces, 1 to 3 ng/mL and 1 to 10 ng/mL in cecal contents, and 3 to 65 ng/mL and 4 to 22 ng/mL in jejunal contents. Following coccidiosis, the overall 3-1E levels started to increase from 4 dpi, and the highest production was shown on 5 dpi. Among the samples collected from Eimeria-infected chickens, the highest detection level was found in the jejunal contents of E. maxima-infected chickens. Furthermore, the level of IFN-γ in serum was significantly (P < 0.05) increased from 3 dpi and peaked on 5 dpi post E. maxima infection. Post E. tenella infection, the level of IFN-γ in serum gradually (P < 0.05) increased from 2 to 5 dpi and plateaued at 7 dpi. The level of TNF-α in serum was rapidly (P < 0.05) increased from 4 dpi and those levels were kept until 7 dpi post both Eimeria infections (E. maxima and E. tenella). More importantly, the daily changes in the 3-1E levels in different samples from E. maxima- and E. tenella-infected chickens were effectively monitored with this new antigen-capture ELISA. Therefore, this new immunoassay is a sensitive diagnostic tool to monitor coccidiosis in a large field population in the commercial poultry farms before clinical symptoms develop using serum, feces, and gut samples during the entire period of infection cycle starting from 1 d after infection.

The effects of protease, xylanase, and xylo-oligosaccharides on growth performance, nutrient utilization, short-chain fatty acids, and microbiota in Eimeria-challenged broiler chickens fed low-protein diet

A total of 392 Cobb 500 off-sex male broiler chicks were used in a 21-day experiment to study the effect of protease, xylanase, and xylo-oligosaccharides (XOS) on improving growth performance, nutrient utilization (ileal digestibility and total tract retention), gene expression of nutrient transporters, cecal short-chain fatty acids (SCFAs), and microbiota profile of broilers challenged with Eimeria spp. Chicks at 0-day old were allocated to 8 treatments in a 4 × 2 factorial arrangement: 1) corn-soybean meal diet with no enzyme (Con); 2) Con plus 0.2 g/kg protease alone (PRO); 3) Con plus 0.2 g/kg protease combined with 0.1 g/kg xylanase (PRO + XYL); or 4) Con plus 0.5 g/kg xylo-oligosaccharides (XOS); with or without Eimeria challenge. The 4 diets were formulated to be marginally low in crude protein (183 g/kg). Challenged groups were inoculated with a solution containing E. maxima, E. acervulina, and E. tenella oocysts on d 15. Eimeria depressed (P < 0.01) growth performance and nutrient utilization. Supplemental protease improved (P < 0.05) body weight gain and feed intake in the prechallenge phase (d 0-15) but had no effect during the infection period (d 15-21). There was no interaction between infection and feed supplementation for nutrient utilization. The supplementations of either PRO or XOS alone increased (P < 0.01) total tract retention of Ca and tended (P < 0.1) to improve total tract retention of N, P, AME, and AMEn. Eimeria decreased (P < 0.05) expressions of GLUT2, GLUT5, PepT1, ATP2B1, CaSR, Calbidin D28K, NPT2, and ZnT1 but increased (P < 0.01) expression of GLUT1. XOS supplementation increased (P < 0.05) ATP2B1 expression. Protease decreased (P < 0.05) isobutyrate concentration in unchallenged treatments but not in challenged treatments. Eimeria decreased (P < 0.01) cecal saccharolytic SCFAs acetate and propionate but increased (P < 0.01) branched-chain fatty acid isovalerate. The supplementation of PRO + XYL or XOS increased (P < 0.05) cecal butyrate or decreased cecal isobutyrate concentrations, respectively. PRO + XYL and XOS decreased cecal protein levels in unchallenged birds but not challenged ones. Eimeria challenge significantly (P < 0.05) decreased the microbial richness (Observed features) and diversity (Shannon index and phylogenetic diversity) and changed the microbial composition by reducing the abundance of certain bacteria, such as Ruminococcus torques, and increasing the abundance of others, such as Anaerostipes. In contrast, none of the additives had any significant effect on the cecal microbial composition. In conclusion, PRO or XOS supplementation individually improved nutrient utilization. All the additives decreased the cecal content of branched-chain fatty acids, consistent with decreased cecal N concentration, although the effects were more pronounced in unchallenged birds. In addition, none of the feed additives impacted the Eimeria-induced microbial perturbation.

Effects of Different Eimeria Inoculation Doses on Growth Performance, Daily Feed Intake, Gut Health, Gut Microbiota, Foot Pad Dermatitis, and Eimeria Gene Expression in Broilers Raised in Floor Pens for 35 Days

The study was conducted to investigate the effects of different Eimeria inoculation doses on the growth performance, gut ecosystem, and body composition of broilers in floor pens for 35 days. A total of 750 15-day-old broilers were allocated to five experimental groups with six replicate pens. The five experimental groups included unchallenged control (CON); Eimeria dose 1 (ED1): E. acervulina: 31,250/E. maxima: 6250/E. tenella: 6250; Eimeria dose 2 (ED2): E. acervulina: 62,500/E. maxima: 12,500/E. tenella: 12,500; Eimeria dose 3 (ED3): E. acervulina: 125,000/E. maxima: 25,000/E. tenella: 25,000; and Eimeria dose 4 (ED4): E. acervulina: 250,000/E. maxima: 50,000/E. tenella: 50,000. On D 21, BW were linearly reduced by increased Eimeria inoculation doses (p < 0.01). On D 35, the Eimeria challenge groups had significantly lower BW compared to the CON group. Increased Eimeria inoculation doses linearly decreased crude fat (CF) (p < 0.01) on D 21. Increased Eimeria inoculation doses tended to increase the relative abundance of the phylum Proteobacteria (p = 0.098) on D 21. On D 35, lean:fat was linearly reduced by increased Eimeria inoculation doses (p < 0.05). Eimeria infection negatively influenced growth performance and gut health in broilers in the acute phase, and the negative effects were prolonged to D 35 in floor pen conditions.

Nutritional Strategies to Improve Meat Quality and Composition in the Challenging Conditions of Broiler Production: A Review

Poultry meat is becoming one of the most important animal protein sources for human beings in terms of health benefits, cost, and production efficiency. Effective genetic selection and nutritional programs have dramatically increased meat yield and broiler production efficiency. However, modern practices in broiler production result in unfavorable meat quality and body composition due to a diverse range of challenging conditions, including bacterial and parasitic infection, heat stress, and the consumption of mycotoxin and oxidized oils. Numerous studies have demonstrated that appropriate nutritional interventions have improved the meat quality and body composition of broiler chickens. Modulating nutritional composition [e.g., energy and crude protein (CP) levels] and amino acids (AA) levels has altered the meat quality and body composition of broiler chickens. The supplementation of bioactive compounds, such as vitamins, probiotics, prebiotics, exogenous enzymes, plant polyphenol compounds, and organic acids, has improved meat quality and changed the body composition of broiler chickens.

Effect of the combination of 25-hydroxyvitamin D3 and higher level of calcium and phosphorus in the diets on bone 3D structural development in pullets

Bone issues such as osteoporosis are major concerns for the laying hen industry. A study was conducted to improve bone-health in pullets. A total of 448 one-day-old Hyline W36 pullets were randomly assigned to four treatments (8 rep; 14 birds/rep) until 17 weeks (wks). Dietary treatments were: 1) vitamin D₃ at (2,760 IU/kg) (D), 2) vitamin D₃ (2,760 IU/kg)+62.5 mg 25-(OH)D₃/ton (H25D), 3) vitamin D₃ (2,760 IU/kg) + 62.5 mg 25-(OH)D₃/ton + high Ca&P (H25D + Ca/P), and 4) vitamin D₃ (2,760 IU/kg) + high Ca&P (D + Ca/P). The high calcium (Ca) and phosphorus (P) diet was modified by increasing both high calcium and phosphorus by 30% (2:1) for the first 12 wks and then only increasing P for 12-17 wks to reduce the Ca to P ratio. At 17 wk, growth performance was measured, whole body composition was measured by dual energy x-ray absorptiometry (DEXA), and femur bones were scanned using Micro-computed tomography (Micro-CT) for bone 3D structure analyses. The data were subjected to a one-way ANOVA using the GLM procedure, with means deemed significant at p < 0.05. There was no significant outcome for growth performance or dual energy x-ray absorptiometry parameters. Micro-computed tomography results indicated that the H25D + Ca/P treatment had lower open pore volume space, open porosity, total volume of pore space, and total porosity in the cortical bone compared to the D + Ca/P. It also showed that a higher cortical bone volume/tissue volume (BV/TV) in the H25D + Ca/P than in the D + Ca/P. Furthermore, the H25D + Ca/P treatment had the lowest trabecular pattern factor and structure model index compared to the other treatments, which indicates its beneficial effects on trabecular structural development. Moreover, the H25D + Ca/P had a higher trabecular percentage compared to the D and 25D, which suggests the additional high calcium and phosphorus supplementation on top of 25D increased trabecular content in the cavity. In conclusion, the combination of 25D with higher levels of high calcium and phosphorus could improve cortical bone quality in pullets and showed a beneficial effect on trabecular bone 3D structural development. Thus, combination of a higher bio-active form of vitamin D₃ and higher levels of high calcium and phosphorus could become a potential feeding strategy to improve bone structural integrity and health in pullets.

Effects of tannic acid supplementation on growth performance, gut health, and meat production and quality of broiler chickens raised in floor pens for 42 days

A study was conducted to investigate the effects of tannic acid (TA) supplementation on growth performance, gut health, antioxidant capacity, gut microbiota, and meat yield and quality in broilers raised for 42 days. A total of 700 one-day-old male broiler chickens (Cobb500) were allocated into 5 treatments with 7 replicates of 20 birds per pen. There were five treatments: 1) tannic acid 0 (TA0: basal diet without TA); 2) tannic acid 0.25 (TA0.25: basal diet+0.25 g/kg TA); 3) tannic acid 0.5 (TA0.5: basal diet+0.5 g/kg TA); 4) tannic acid 1 (TA1: basal diet+1 g/kg TA); and 5) tannic acid 2 (TA2: basal diet+2 g/kg TA). The dietary phases included starter (D 0 to 18; crumble feed), grower (D 18 to 28; pellet feed), and finisher (D 28 to 42; pellet feed). On D 18, the supplementation of TA linearly reduced body weight (BW) and average daily feed intake (ADFI) (p < 0.05), and on D 28, the supplementation of TA linearly reduced BW, average daily gain (ADG), and feed conversion ratio (FCR) (p < 0.05). Relative mRNA expression of genes related to mucin production (MUC2), tight junction proteins (CLDN2 and JAM2), and nutrient transporters (B0AT1 and SGLT1) was linearly increased by the supplementation of TA (p < 0.05). The supplementation of TA tended to linearly increase the relative abundance of the family Enterobacteriaceae (p = 0.08) and quadratically increased the relative abundance of the families Lachnospiraceae and Ruminococcaceae in the cecal microbial communities (p < 0.05). On D 36, the ratio of the phyla Firmicutes and Bacteroidetes was quadratically reduced by the supplementation of TA (p < 0.05). On D 42, bone mineral density and the lean to fat ratio were linearly decreased by the supplementation of TA (p < 0.05). On D 43, total chilled carcass weight was linearly reduced (p < 0.05), and proportion of leg weight was increased by supplementation of TA (p < 0.05). The supplementation of TA linearly reduced pH of the breast meat (p < 0.05) and linearly increased redness (a*) (p < 0.05). Although the supplementation of TA positively influenced gut health and gut microbiota in the starter/grower phases, it negatively affected overall growth performance, bone health, and meat production in broilers on D 42.

Interactions of Microbiota and Mucosal Immunity in the Ceca of Broiler Chickens Infected with Eimeria tenella

The purpose of the study was to investigate the effects of Eimeria tenella infection on the cecal microbiome, the protein concentration of cecal content, cecal mucosal immunity, and serum endotoxin levels in broilers. Three hundred sixty 14-day-old broilers were allocated to five infection doses with six replicates. The five infection doses were: ID0: 0, ID1: 6250, ID2: 12,500, ID3: 25,000, and ID4: 50,000 Eimeria tenella oocysts. Eimeria tenella infection significantly increased the relative abundance of the phylum Proteobacteria, which includes diverse pathogenic bacteria, and significantly decreased the relative abundance of the phylum Firmicutes. Protein concentration of the cecal content was linearly increased (p < 0.05), and the concentration of secretory immunoglobulin A (sIgA) in the cecal content was linearly decreased by Eimeria tenella infection (p < 0.05). Goblet cell density was linearly reduced in the ceca by Eimeria tenella infection (p < 0.05). Eimeria tenella infection tended to linearly decrease the relative mRNA expression of antimicrobial peptide genes such as avian beta-defensin 9 (AvBD9; p = 0.10) and liver-expressed antimicrobial peptide 2 (LEAP2; p = 0.08) in the cecal tissue. Therefore, Eimeria tenella infection negatively modulated cecal microbiota via impairing cecal mucosal immunity and increasing protein concentration in the cecal content in broilers.

Effects of supplemental tannic acid on growth performance, gut health, microbiota, and fat accumulation and optimal dosages of tannic acid in broilers

This study was conducted to investigate the effects of different dosages of tannic acid (TA) on growth performance, nutrient digestibility, gut health, immune system, oxidative status, microbial composition, volatile fatty acids (VFA), bone mineral density, and fat digestion and accumulation in broilers and to find optimal dosages of TA for efficient growth and gut health in broilers. A total of 320 male Cobb500 broilers were randomly distributed to 4 treatments with 8 replicates including 1) tannic acid 0 (TA0): basal diet without TA; 2) tannic acid 0.5 (TA0.5): basal diet with 0.5 g/kg TA; 3) tannic acid 1.5 (TA1.5); and 4) tannic acid 2.5 (TA2.5). Supplemental TA at levels greater than 972 mg/kg tended to reduce BW on D 21 (p = 0.05). The TA2.5 had significantly lower apparent ileal digestibility (AID) of crude protein compared to the TA0 group. The AID of ether extract tended to be reduced by TA at levels greater than 525 mg/kg (p = 0.08). The jejunal lipase activities tended to be reduced by TA at levels less than 595.3 mg/kg (p = 0.09). TA linearly decreased goblet cell density in the crypts of the jejunum (p < 0.05) and reduced mRNA expression of mucin two at levels less than 784.9 mg/kg and zonula occludens two at levels less than 892.6 mg/kg (p < 0.05). The TA0.5 group had higher activities of liver superoxide dismutase compared to the TA0 group (p < 0.05). Bone mineral density and contents tended to be linearly decreased by TA (p = 0.05), and the ratio of lean to fat was linearly decreased (p < 0.01). Total cecal VFA production tended to be linearly reduced by TA at levels greater than 850.9 mg/kg (p = 0.07). Supplemental TA tended to increase the relative abundance of the phylum Bacteroidetes (p = 0.1) and decrease the relative abundance of the phylum Proteobacteria (p = 0.1). The relative abundance of the family Rikenellaceae was the lowest at 500 mg/kg TA, and the relative abundance of the family Bacillaceae was the highest at 1,045 mg/kg TA. Collectively, these results indicate that the optimum level of supplemental TA would range between 500 and 900 mg/kg; this range of TA supplementation would improve gut health without negatively affecting growth performance in broilers under antibiotic-free conditions.

Time-series transcriptome analysis identified differentially expressed genes in broiler chicken infected with mixed Eimeria species

Coccidiosis caused by the Eimeria species is a highly problematic disease in the chicken industry. Here, we used RNA sequencing to observe the time-dependent host responses of Eimeria-infected chickens to examine the genes and biological functions associated with immunity to the parasite. Transcriptome analysis was performed at three time points: 4, 7, and 21 days post-infection (dpi). Based on the changes in gene expression patterns, we defined three groups of genes that showed differential expression. This enabled us to capture evidence of endoplasmic reticulum stress at the initial stage of Eimeria infection. Furthermore, we found that innate immune responses against the parasite were activated at the first exposure; they then showed gradual normalization. Although the cytokine-cytokine receptor interaction pathway was significantly operative at 4 dpi, its downregulation led to an anti-inflammatory effect. Additionally, the construction of gene co-expression networks enabled identification of immunoregulation hub genes and critical pattern recognition receptors after Eimeria infection. Our results provide a detailed understanding of the host-pathogen interaction between chicken and Eimeria. The clusters of genes defined in this study can be utilized to improve chickens for coccidiosis control.

Antimicrobial and immunomodulatory effects of tannic acid supplementation in broilers infected with Salmonella Typhimurium

Infection by Salmonella Typhimurium, a food-borne pathogen, can reduce the poultry production efficiency. The objective of this study was to investigate the effects of tannic acid (TA) supplementation on growth performance, Salmonella colonization, gut barrier integrity, serum endotoxin levels, antioxidant capacity, gut health, and immune function in broilers infected with the Salmonella enterica serovar Typhimurium nalidixic acid resistant strain (ST^NR). A total of 546 one-day-old broilers were arbitrarily allocated into 6 treatments including 1) Sham-challenged control (SCC; birds fed a basal diet and administrated peptone water); 2) Challenged control (CC; birds fed a basal diet and inoculated with 10⁸ ST^NR); 3) Tannic acid 0.25 (TA0.25; CC + 0.25 g/kg TA); 4) TA0.5 (CC + 0.5 g/kg TA); 5) TA1 (CC + 1 g/kg TA); and 6) TA2 (CC + 2 g/kg TA). On D 7, supplemental TA linearly reduced ST^NR colonization in the ceca (P < 0.01), and TA1 and TA2 group had significantly lower reduced ST^NR colonization in the ceca (P < 0.01). On D 7 to 21, average daily gain tended to be linearly increased by supplemental TA (P = 0.097). The serum endotoxin levels were quadratically decreased by supplemental TA on D 21 (P < 0.05). Supplemental TA quadratically increased ileal villus height (VH; P < 0.05), and the TA0.25 group had higher ileal VH compared to the CC group (P < 0.05). Supplemental TA linearly increased percentage of peripheral blood CD8⁺ T cells on D 18 (P < 0.01). The TA0.5 group had significantly lower lymphocyte numbers compared to the CC groups (P < 0.05). The abundance of monocytes linearly increased with TA supplementation (P < 0.01). Therefore, broilers fed TA had reduced ST^NR colonization, increased growth performance, decreased serum endotoxin levels, enhanced gut health in the broilers, and stimulated the immune system in broilers infected with ST^NR. Supplementation of TA (1–2 g/kg) enhanced growth performance and gut health via antimicrobial and immunostimulatory effects in broilers infected with ST^NR.

Effects of Tannic Acid Supplementation on Growth Performance, Oocyst Shedding, and Gut Health of in Broilers Infected with Eimeria Maxima

The purpose of this study was to evaluate effects of tannic acid (TA) on growth performance, fecal moisture content, oocyst shedding, gut permeability, lesion score, intestinal morphology, apparent ileal digestibility, and the antioxidant and immune system of broilers infected with Eimeria maxima. A total of 420 one-day-old broilers were distributed to five treatments with seven replicates of 12 birds. The five treatments were the (1) sham-challenged control (SCC; birds fed a control diet and administrated with PBS); (2) challenged control (CC; birds fed a control diet and inoculated with E. maxima); (3) tannic acid 0.5 (TA0.5; CC + 500 mg/kg TA); (4) tannic acid 2.75 (TA2.75; CC + 2750 mg/kg TA); and (5) tannic acid 5 (TA5; CC + 5000 mg/kg TA). The TA2.75 group had significantly lower gut permeability compared to the CC group at 5 days post-infection (dpi). Supplementation of TA linearly reduced oocyst shedding of E. maxima at 7 to 9 dpi (p < 0.05). At 13 dpi, the TA2.75 group had significantly greater apparent ileal digestibility (AID) of dry matter (DM) and organic matter (OM) compared to the CC group. At 13 dpi, supplementation of TA linearly increased jejunal villus height (VH). Thus, this study showed that supplementation of TA at levels of 500 to 2750 mg/kg has the potential to be an anti-coccidial agent against E. maxima in broilers.