Assessment of dietary supplementation with probiotics on performance, intestinal morphology and microflora of chickens infected with Eimeria tenella

Investigation of Betaine and Vaccine Efficacy for Coccidiosis Prevention in Broilers

PURPOSE

This study aimed to assess the anticoccidial effects of betaine and a vaccine compared to monensin sodium in experimentally induced coccidiosis in broiler chickens.

METHODS

600 day-old broiler chickens (Ross 308) were randomly assigned to five groups, each with four replicates of 30 birds. While the control group received a basal diet, two experimental groups received basal diet supplemented with either 100 mg/kg monensin sodium or 2.0 g/kg betaine. The remaining experimental groups received a commercial coccidiosis vaccine alone or in combination with betaine. All chickens were challenged with sporulated field-mixed Eimeria species at 20 days of age.

RESULTS

Throughout the study, vaccinated birds showed superior performance in terms of body weight gain (BWG) and feed conversion ratio (FCR) compared to other anticoccidial treatments (P < 0.05), followed by betaine, vaccine + betaine, and monensin treatments in descending order. While all anticoccidial regimens significantly reduced fecal oocyst output only at the beginning of the observation period, this effect diminished thereafter (P < 0.05). Supplementation with monensin and vaccination against coccidiosis significantly decreased small intestine weight compared to untreated controls (P < 0.01), with a numerical decrease observed in chicks fed betaine-supplemented diets and treated with the combination of betaine and vaccine.

CONCLUSION

Notably, there has been no prior study comparing betaine with monensin sodium and a coccidiosis vaccine. These findings suggest that dietary betaine supplementation and a commercial coccidiosis vaccine containing mixed Eimeria spp. may offer benefits in controlling coccidiosis, presenting viable, cost-effective, sustainable, and safe alternatives to conventional ionophore anticoccidials, with added benefits of no residue and reduced resistance hazards for both animal and human consumption.

The anticoccidial effects of probiotics and prebiotics on the live coccidia vaccine and the subsequent influence on poultry performance post-challenge with mixed Eimeria species

Live vaccines containing Eimeria oocysts are commercially available to protect against avian coccidiosis. Additionally, probiotics (PRO) and prebiotics (PRE) improve the poultry productivity and health and can be used as anticoccidial substitutes. However, the impact of PRO and PRE on reproductive potential, lesion score, intestinal health, and immunization outcomes of the live coccidia vaccines has not received adequate attention. Five groups of unsexed 1-day-old broiler chicks were used as follows: negative control (NC); challenged control (CC); vaccinated and challenged (VC); vaccinated, PRO-treated, and challenged (V-PRO); and vaccinated, PRE-treated, and challenged (V-PRE). At 21 d post-vaccination (pv), the vaccine increased the count of cecal anaerobes (P ≤ 0.05) and coliforms (P > 0.05) as well as harmed body weight gain (WG) (P ≤ 0.05), cecal lactic acid bacteria (P ≤ 0.05), and plasma carotenoid level (P > 0.05). None of the additives decreased oocyst shedding after vaccination, although they lowered the middle intestine and cecal lesion scores (P > 0.05). Compared to VC (2.68 ± 0.12) and V-PRE (2.66 ± 0.05), the V-PRO group showed an improved carotenoid level pv (2.96 ± 0.05) (P ≤ 0.05). V-PRE exhibited higher WG (822.95 ± 18.25) (P > 0.05) and FI (1153.01 ± 10.02) (P ≤ 0.05) than VC (781.86 ± 25.16 and 1109.85 ± 33.68) and V-PRO pv (787.61 ± 19.92 and 1077.43 ± 15.99). Following the homologous coccidia challenge, coccidia-vaccinated broilers adminstered the PRO or PRE continued to exhibit protection levels comparable to those received the vaccine alone. During 2 weeks post-challenge, VC, V-PRO and V-PRE improved bird performance and reduced oocyst shedding and lesion scores compared to CC. Ultimately, PRO and PRE treatments did not significantly reverse the reduction in growth performance in broiler chickens vaccinated against coccidia during the 1st three weeks of age.

Effect of In Ovo Supplementation of Slab51 Probiotic Mixture, Associated with Marek's Disease Vaccine, on Growth Performance, Intestinal Morphology and Eimeria spp. Infection in Broiler Chickens

The interest for in ovo feeding has grown in the last decades mainly concerning probiotics, live microorganisms that can actively interact with the embryo. The aim of this study was to evaluate the effects of a multi-strain probiotic diluted in Marek's disease vaccine (MDV) on zootechnical performances, intestinal morphology and Eimeria spp. infection. One hundred and twenty eggs of Ross 308 broiler chickens were incubated until 18 d, when 105 fertilised and vital eggs were randomly allocated into three groups. A control group (C) was inoculated with MDV; two treated groups (P1 and P2) were inoculated with MDV and different concentrations of probiotics: 1 × 105 CFU/100 μL in P1 and 1 × 106 CFU/100 μL in P2. After hatching, chickens were separated into three replicates (10/replicate). Zootechnical parameters were determined. At the end of the cycle (35 d), chickens were slaughtered, and the intestine was collected for morphological analysis from nine chickens per group (three/replicate). Eimeria spp. oocyst shedding was determined weekly, and parasitic lesions were analysed on the histological sample. In ovo treatment with probiotic did not influence hatching rate but significantly improved body weight and positively influenced intestinal morphometric data compared to C. Oocyst shedding in faeces resulted in an increase in C, with significant differences at sampling performed at 14, 21 and 28 d of age. These results suggest that the tested probiotic compound is safe for in ovo supplementation and effectively improves zootechnical performances and coccidian resistance.

Alleviating Pentatrichomonas hominis-induced damage in IPEC-J2 cells: the beneficial influence of porcine-derived lactobacilli

Pentatrichomonas hominis is a common intestinal parasitic protozoan that causes abdominal pain and diarrhea, and poses a zoonotic risk. Probiotics, known for enhancing immunity and pathogen resistance, hold promise in combating parasitic infections. This study aimed to evaluate two porcine-derived probiotics, Lactobacillus reuteri LR1 and Lactobacillus plantarum LP1, against P. hominis infections in pigs. Taxonomic identity was confirmed through 16 S rRNA gene sequencing, with L. reuteri LR1 belonging to L. reuteri species and L. plantarum LP1 belonging to L. plantarum species. Both probiotics exhibited robust in vitro growth performance. Co-culturing intestinal porcine epithelial cell line (IPEC-J2) with these probiotics significantly improved cell viability compared with the control group. Pre-incubation probiotics significantly enhanced the mRNA expression of anti-oxidative response genes in IPEC-J2 cells compared with the PHGD group, with L. reuteri LR1 and L. plantarum LP1 significantly up-regulating CuZn-SOD、CAT and Mn-SOD genes expression (p < 0.05). The anti-oxidative stress effect of L. reuteri LR1 was significantly better than that of L. plantarum LP1 (p < 0.05). Furthermore, pre-incubation with the probiotics alleviated the P. hominis-induced inflammatory response. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated IL-6、IL-8 and TNF-α gene expression(p < 0.05) compared with the PHGD group. The probiotics also mitigated P. hominis-induced apoptosis. L. reuteri LR1 and L. plantarum LP1 significantly down-regulated Caspase3 and Bax gene expression (p < 0.05), significantly up-regulated Bcl-2 gene expression (p < 0.05) compared with the PHGD group. Among them, L. plantarum LP1 showed better anti-apoptotic effect. These findings highlight the probiotics for mitigating P. hominis infections in pigs. Their ability to enhance anti-oxidative responses, alleviate inflammation, and inhibit apoptosis holds promise for therapeutic applications. Simultaneously, probiotics can actively contribute to inhibiting trichomonal infections, offering a novel approach for preventing and treating diseases such as P. hominis. Further in vivo studies are required to validate these results and explore their potential in animal and human health.

Comparing the effect of phytobiotic, coccidiostat, toltrazuril, and vaccine on the prevention and treatment of coccidiosis in broilers

This study compared 2 herbal anticoccidiosis drugs (water-soluble and feed-additive drugs) with monensin coccidiostat, toltrazuril (TTZ, anticoccidiosis drug), and Livacox Q (anticoccidiosis vaccine) in terms of their effects on the prevention and treatment of coccidiosis in broilers. In this study, 280 Ross 308 broiler chickens (a mix of both genders) were used in a completely randomized design with 7 treatments and 5 replications each including 8 chickens per replicate. On d 21 of rearing, all experimental groups, except for the negative control group (NC), were challenged with a mixed suspension of common strains of Eimeria, and the intended indices were assessed, including performance indices, number of oocysts per gram (OPG) of feces, intestinal injuries, and the total number of intestinal bacteria. In addition, the NC and the group receiving the monensin had greater body weight gain (BWG) (P < 0.05). At the end of week 6, the monensin group had the highest feed intake (FI), while the water soluble medicine treatment resulted in the lowest feed intake (P < 0.05). Regarding the lesion scores on day 28, the highest and lowest rates of jejunal injuries were observed in the positive control group (PC), the monensin and vaccine group respectively. The rate of oocysts excretion (oocysts per gram of feces = OPG) on different days was higher in the PC group, and the use of monensin could further reduce excretion compared to the other groups (P > 0.05). Based on a comparison of the population of lactic acid bacteria between the NC and both medicinal plant treated groups, the use of these products could increase the population of these types of bacteria. Moreover, the population of Escherichia coli was less considerable in the NC and herbal powder groups (P < 0.05). Overall, similar to commercial medicines, the herbal medicines used in this project can be effective in the prevention and treatment of coccidiosis and can improve profitability in broiler rearing centers by improving intestinal health.

Role of Nrf2/HO-1 pathway on inhibiting activation of ChTLR15/ChNLRP3 inflammatory pathway stimulated by E. tenella sporozoites

The aim of this study is to explore whether Nrf2 antioxidant pathway negatively regulates the ChTLR15/NLRP3 inflammatory pathway stimulated by Eimeria tenella infection. Firstly, levels of molecules in the Nrf2/HO-1 pathway in DF-1 cells pre-treated with an optimized dose of Corilagine or probiotics Levilactobacillus brevis 23017 were quantified using real-time PCR (qRT-PCR) and Western blot. Then, DF-1 cells pre-treated with Corilagine or L. brevis 23017 were stimulated with E. tenella sporozoites, and mRNA levels of molecules in Nrf2/HO-1 and ChTLR15/NLRP3 pathways, protein levels of p-Nrf2, Nrf2, HO-1, ChTLR15 and ChNLRP3, levels of malondialdehyde (MDA) and reactive oxygen species (ROS) were quantified. Further, expression level of Nrf2 and ChTLR15 in DF-1 cells was knocked down by RNA interfering (RNAi) method, and target cells were pre-treated with Corilagine or L. brevis 23017, followed by stimulation with E. tenella sporozoites, and the expression levels of key molecules in Nrf2/HO-1 and ChTLR15/NLRP3 pathways were quantified. The results showed that mRNA and protein levels of key molecules in the Nrf2/HO-1 pathway in DF-1 cells was significantly upregulated after pretreating with 15 μM Corilagine and supernatant of L. brevis 23017. After stimulating with E. tenella sporozoites, levels of molecules in the ChTLR15/NLRP3 pathway, levels of MDA and ROS in DF-1 cells pre-treated with 15 μM Corilagine or bacterial supernatant were all significantly down-regulated. The results from the knock-down experiment also displayed that Corrigine and L. brevis 23017 inhibited the activation of the ChTLR15/ChNLRP3 inflammatory pathway stimulated by E. tenella sporozoites through activating Nrf2/HO-1 antioxidant pathway. This study provides new ideas for the development of novel anticoccidial products.

The effects of probiotic and threonine application on the carcass yield, internal organ development, intestinal morphology and cecal microbiota of broilers challenged with Clostridium perfringens

The aim of this study was to explore the effects of probiotics (Ecobiol®) and threonine supplements on broiler internal organs and intestinal health under Clostridium perfringens challenge. A total of 1600 male Ross 308 broiler chicks were randomly assigned to eight treatments with eight replicates each of 25 birds. Dietary treatments consisted of two levels of supplemented threonine (without and with threonine supplementation), two levels of probiotics (Ecobiol®) supplement (0 and 0. 1% of diet), and two levels of challenge (without and with 1 ml of the C. perfringens inoculum (∼10⁸ cfu/ml) on d 14, 15, and 16 of the experiment), which fed to the birds during a 42 d feeding trial. The results showed that adding threonine and probiotic supplements to the diets of C. perfringens-infected birds reduced the relative gizzard weight by 22.9% compared to those fed un-supplemented diet (P ≤ 0.024). As compared to the non-challenged group, the C. perfringens challenge significantly reduced the carcass yield of broilers by 1.18% (P < 0.0004). The groups receiving threonine and probiotic supplementation had higher carcass yield, and the inclusion of probiotics in the diet decreased abdominal fat by 16.18% compared with the control treatment (P ≤ 0.001). Adding threonine and probiotic supplements to the diets of broilers challenged with C. perfringens increased the jejunum villus height in comparison with C. perfringens-infected group fed an unsupplemented diet on day 18 (P ≤ 0.019). The number of cecal E. coli increased in birds under C. perfringens challenge in comparison with the negative group. Based on the findings, dietary inclusion of threonine and probiotic supplement could beneficially affect intestine health and carcass weight during the C. perfringens challenge.

The synergetic potential of Lactobacillus delbrueckii and Lactobacillus fermentum probiotics in alleviating the outcome of acute toxoplasmosis in mice

Toxoplasmosis is an immunologically complex disease, particularly in immunocompromised patients. Although there are several therapeutic regimens for such disease, the majority of them have many drawbacks. Therefore, it is of utmost importance to improve the current regimen in an effort to achieve a well-tolerated therapy while also enhancing the host immune response. Famous for their immunomodulatory effect, Lactobacillus delbrueckii and Lactobacillus fermentum probiotics were chosen to be evaluated in this study as an adjuvant therapy against the virulent RH Toxoplasma gondii (T. gondii) strain. Experimental mice were divided into control and treated groups. The control group was further subdivided into two groups: group I: 10 uninfected mice and group II: 20 infected untreated mice. The treated experimental group was subdivided into three groups (20 mice each); group III: sulfamethoxazole-trimethoprim (SMZ-TMP) treated, group IV: probiotics treated, and group V: SMZ-TMP combined with probiotics. The results obtained revealed that combined therapy increased survival rate and time up to 95% and 16 days, respectively, with an 82% reduction of tachyzoites and marked distortion, as detected by the scanning electron microscope (SEM). Additionally, combined therapy alleviated the severity and the extent of the inflammatory cells' infiltration, thereby reducing hepatocyte degeneration. Intriguingly, serum IF-γ level showed a significant increase to 155.92 ± 10.12 ng/L with combined therapy, reflecting the immunological role of the combined therapy. The current results revealed that probiotics have a high adjuvant potential in alleviating the impact of toxoplasmosis. Using probiotics as a synergistic treatment to modulate conventional therapy in systemic toxoplasmosis may gain popularity due to their low cost and current availability.

Mechanistic Approaches to the Application of Nano-Zinc in the Poultry and Biomedical Industries: A Comprehensive Review of Future Perspectives and Challenges

Bio-fortification is a new, viable, cost-effective, and long-term method of administering crucial minerals to a populace with limited exposure to diversified foods and other nutritional regimens. Nanotechnology entities aid in the improvement of traditional nutraceutical absorption, digestibility, and bio-availability. Nano-applications are employed in poultry systems utilizing readily accessible instruments and processes that have no negative impact on animal health and welfare. Nanotechnology is a sophisticated innovation in the realm of biomedical engineering that is used to diagnose and cure various poultry ailments. In the 21st century, zinc nanoparticles had received a lot of considerable interest due to their unusual features. ZnO NPs exhibit antibacterial properties; however, the qualities of nanoparticles (NPs) vary with their size and structure, rendering them adaptable to diverse uses. ZnO NPs have shown remarkable promise in bio-imaging and drug delivery due to their high bio-compatibility. The green synthesized nanoparticles have robust biological activities and are used in a variety of biological applications across industries. The current review also discusses the formulation and recent advancements of zinc oxide nanoparticles from plant sources (such as leaves, stems, bark, roots, rhizomes, fruits, flowers, and seeds) and their anti-cancerous activities, activities in wound healing, and drug delivery, followed by a detailed discussion of their mechanisms of action.

Compound probiotics can improve intestinal health by affecting the gut microbiota of broilers

Probiotics, as a widely used additive, have played a unique advantage in replacing antibiotic products. As a result, the probiotic effects on broiler development, intestinal flora, intestinal barrier, and immunity were assessed by this investigation. Four hundred and eighty 1-day-old Arbor Acres broilers were randomly allotted to 4 groups of 5 replicates with 24 broilers each. The control was fed only a basal corn-soybean meal diet. Probiotics I, probiotics II, and probiotics III were fed basal diet and 1, 5, and 10 g/kg compound probiotics (Lactobacillus casei: Lactobacillus acidophilus: Bifidobacterium = 1:1:2), respectively. We found that broilers in the compound probiotic group exhibited better growth performance and carcass characteristics compared with control, especially among probiotics III group. The intestinal barrier-related genes relative expression of Claudin, Occludin, MUC2, and ZO-1 mRNA in the probiotic group increased at 21 and 42 d compared with control, especially among probiotics III group (P < 0.05). The early gut immune-related genes (TLR2, TLR4, IL-1β, and IL-2) mRNA increased compared with control, while the trend at 42 d was completely opposite to that in the earlier stage (P < 0.05). Among them, probiotics III group showed the most significant changes compared to probiotics II group and probiotics I group. Select probiotics III group and control group for 16S rDNA amplicon sequencing analysis. The 16S rDNA amplicon sequencing results demonstrated that probiotics increased the relative abundance of beneficial microbes such as o_Bacteroidales, f_Rikenellaceae, and g_Alistipes and improved the cecum's gut microbiota of 42-day-old broilers. Additionally, adding the probiotics decreased the relative abundance of harmful microbes such as Proteobacteria. PICRUSt2 functional analysis revealed that most proteins were enriched in DNA replication, transcription, and glycolysis processes. Therefore, this study can provide theoretical reference value for probiotics to improve production performance, improve intestinal barrier, immunity, intestinal flora of broilers, and the application of probiotics.

Bacillus subtilis and Pichia farinose mixture improves growth performance and nutrient absorption capacity in broiler chicks

Introduction

This study evaluated the effects of dietary supplementation of Bacillus subtilis and Pichia farinose mixture (BPM) on growth performance, apparent ileal digestibility, cecal bacteria counts, small intestinal morphology and digestive enzymes activities, and jejunal nutrient transporters gene expression in broiler chicks.

Methods

A total of 768 one-day-old Ross 308 broiler chicks were randomly Q18 assigned into 3 groups based on the initial body weight (42.00 ± 0.08 g). The experimental periods were 35 days. There were 16 replicates per group and 16 birds per cage. Dietary treatments included a basal diet supplemented with 0, 0.1, or 0.2% BPM to form CON, BPM0.1 (consisting Bacillus subtilis with 1.0 × 107 viable spore and Pichia farinose with 1.0 × 107 viable spore per kg diet), and BPM0.2 (consisting Bacillus subtilis with 2.0 × 107 viable spore and Pichia farinose with 2.0 × 107 viable spore per kg diet) groups.

Results and discussion

Dietary supplementation of graded levels of BPM has positive effects on growth performance of broiler chicks, manifesting in the increase of body weight gain during days 1-35 as well as the decrease of feed conversion ratio during days 1-7, 21-35, and 1-35. Moreover, BPM supplementation positively improved ileal energy and crude protein digestibility, increased Lactobacillus counts, optimized intestinal morphology, enhanced intestinal digestive enzymes activities, and upregulated jejunal SGLT-1, GLUT-2, and PEPT-1 expression. Therefore, BPM supplementation improved growth performance of broiler chicks, which was partially related to the improvement in intestinal nutrient absorption capacity.

Changes of oxidant-antioxidant parameters in small intestines from rabbits infected with E. intestinalis and E. magna

Rabbit coccidiosis is a very serious disease caused by protozoan parasites of the genus Eimeria, which increases the production rate of free radicals, especially reactive oxygen species. When the generation of free radicals exceeds the scavenging capacity of the body’s antioxidant system, the oxidant-antioxidant balance is broken, resulting in oxidative stress. This study was designed to investigate the effect on the oxidant-antioxidant status of rabbits infected with E. intestinalis and E. magna. To this end, eighteen 30-d-old weaned rabbits were randomly allocated into three groups as follows: the E. intestinalis infection group with 3×103 sporulated oocysts of E. intestinalis, the E. magna infection group with 20×103 sporulated oocysts of E. magna, and the uninfected control group. We measured the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) and the contents of malondialdehyde (MDA) in rabbits’ small intestinal tissues (duodenum, jejunum and ileum) of the three groupson day 8. The results showed that CAT activity and MDA levels significantly increased, while the activities of SOD, GSH-Px and T-AOC decreased after E. intestinalis and E. magna infection. Besides, the jejunum and ileum were particularly damaged in the rabbits. It is concluded that the pathological oxidative stress occurs during the E. intestinalis and E. magna infection process and the body’s oxidant-antioxidant balance is disrupted.

Meta-Analysis of the Use of Eimeria Lesion Scores and Oocyst Counts in Floor-Pen Studies

The success of treatments for, or prophylaxis of, coccidiosis with classical anticoccidial feed additives or alternative treatments can be measured with a variety of metrics. Three important metrics are body weight or body weight gain (BW or BWG), lesion scores (LS), and oocyst shedding (OS). A meta-analysis of floor-pen experiments was performed to determine if using LS and OS would lead to systematically different assessments compared to the use of BW at the end of the experiment, and to what degree changes in LS and OS are correlated with BW. We also investigated if there were days postinfection on which one could expect larger ratios between untreated control groups and treated groups for LS and OS as an aid to selecting sampling days. A total of 38 experiments from 37 articles in peer-reviewed journals were included. Data sets containing experiments that investigated LS or OS in addition to BW or BWG to assess anticoccidial feed additives or alternative treatment were tested for the effectiveness of the intervention either by univariate meta-analyses for each metric or by robust variance estimation multivariate meta-analysis combining BW with LS or BW with OS. The results did not show evidence that the inclusion of LS and OS in experimental designs to assess the effect of conventional and alternative feed additives with assumed anticoccidial activity systematically changed the conclusions drawn from an experiment, but there was no significant correlation between the LS and OS ratios of untreated and treated groups determined during the experiments with the ratios of the BW at the end of the experiment for each experiment. There was also no discernible relationship between LS or OS ratios and days postinfection.

Effects of challenge with Clostridium perfringens, Eimeria and both on ileal microbiota of yellow feather broilers

In the poultry industry worldwide, Clostridium perfringens has been causing major economic loss as it can cause necrotic enteritis (NE). The coccidial infection has been considered as the most important predisposing factor of NE caused by C. perfringens. In this study, we aimed to advance our knowledge on ileal microbiota of yellow feather broilers under C. perfringens and/or Eimeria challenge. Total of 80 healthy day old yellow feather broilers were randomly assigned to four groups including: Control, C. perfringens challenge group (C. Per), Eimeria challenge group (Cocc), and C. perfringens plus Eimeria challenge group (Comb). On day 14, the Cocc and Comb group broilers were orally gavaged 1 ml PBS solution containing 25,000 oocysts of Eimeria brunetti and 25,000 oocysts of Eimeria maxima. Starting on day 17, the C. Per and Comb group broilers were orally gavaged 10 mL of C. perfringens per bird (4 × 107 CFU/mL, ATCC® 13124™ Strain) every day for 6 days. 16S rRNA gene sequencing was performed on extracted DNA of ileal digesta samples. The results showed that C. perfringens alone did not affect the alpha diversity of ileal microbiome in yellow feather broilers but co-infection with Eimeria significantly decreased the diversity of ileal microbiota. C. perfringens and Eimeria challenge also decreased the relative abundance of beneficial bacteria including Bacteroidetes at the phylum level and Faecalibacterium at the genus level. At the species level, the relative abundance of Candidatus Arthromitus was significantly decreased in the Eimeria challenged groups. This microbial shift information of ileal microbiota under C. Perfringens and Eimeria challenge provide important reference data for the development of therapeutic approaches to necrotic enteritis in yellow-feather broiler chickens.

Construction of constitutive expression of Eimeria tenella eukaryotic initiation factor U6L5H2 on the surface of Lactobacillus plantarum and evaluation of its immunoprotective efficiency against chicken coccidiosis

Lactobacillus strains exhibit preferable properties that make them attractive candidates for vaccine delivery systems because of their ability to regulate intestinal mucosal immunity in the body. To date, live Lactobacillus delivery vaccines reported for the defense against Eimeria tenella have been inducer-dependent systems whose applications are significantly limited due to their unattainable induction conditions in vivo. Here, a constitutive expression of Lactobacillus plantarum NC8 surface display system was constructed. Then, this system was used to prepare a live oral vaccine to constitutively express the E. tenella U6L5H2 (EtU6) protein on the NC8 surface and to evaluate its protective efficacy against E. tenella challenge in chickens. The results showed that the heterologous protein (EGFP or EtU6) was successfully expressed on the surface of L. plantarum NC8 without any inducer. The immunoprotection of EtU6 with constitutive expression in L. plantarum NC8 system (NC8/Pc-EtU6) was significantly stronger than that of EtU6 with induced expression of L. plantarum NC8 system (NC8/Pi-EtU6) (ACI: 168.28 vs. 152.74) as evidenced by increased body weight, decreased oocyst output and lesion scores. Furthermore, the constitutive system NC8/Pc-EtU6 produced higher levels of specific cecal SIgA, serum IgG, transcription of cytokines IFN-γ and IL-2, and lymphocyte proliferation than the induced system NC8/Pi-EtU6. These results indicate that, compared to the inducible system, the constitutive surface display system of L. plantarum has the advantages of continuously expressing antigens in vivo and stimulating the host immune system. It could be an ideal platform for vaccine expression. The live vector vaccine for coccidiosis constructed by this constitutive system greatly improves the application potential in chicken production and provides a novel platform for the prevention of coccidiosis in chickens.

Probiotics in Poultry Nutrition as a Natural Alternative for Antibiotics

Since the early 1950s, antibiotics have been used in poultry for improving feed efficiency and growth performance. Nevertheless, various side effects have appeared, such as antibiotic resistance, antibiotic residues in eggs and meat, and imbalance of beneficial intestinal bacteria. Consequently, it is essential to find other alternatives that include probiotics that improve poultry production. Probiotics are live microorganisms administered in adequate doses and improve host health. Probiotics are available to be used as feed additives, increasing the availability of the nutrients for enhanced growth by digesting the feed properly. Immunity and meat and egg quality can be improved by supplementation of probiotics in poultry feed. Furthermore, the major reason for using probiotics as feed additives is that they can compete with various infectious diseases causing pathogens in poultry's gastrointestinal tract. Hence, this chapter focuses on the types and mechanisms of action of probiotics and their benefits, by feed supplementation, for poultry health and production.

Comparison of functional-oil blend and anticoccidial antibiotics effects on performance and microbiota of broiler chickens challenged by coccidiosis

This study aimed to compare the effects of different levels of cashew nutshell liquid (CNSL) and castor oil (CNSL-castor oil) with growth-promoting antibiotics associated with anticoccidials in broiler chickens challenged with coccidiosis. In this work, 2520 one-day-old male broiler chicks (Cobb) were randomly assigned to 84 pens, containing 30 birds each. The experimental design was completely randomized, with seven treatments: enramycin (8 ppm), virginiamycin (16.5 ppm), and tylosin (55 ppm); different doses of CNSL-castor oil (0.5, 0.75, and 1.00 kg/t); and a control diet (without additives). All treatments received semduramicin + nicarbazin (500 g/t; Aviax® Plus) from 0 to 28 d and monensin sodium (100 ppm; Elanco) from 29 to 35 days of age, when the feed was without antibiotics. The challenge was introduced at 14 days of age by inoculating broiler chickens with sporulated Eimeria tenella, Eimeria acervulina, and Eimeria maxima oocysts via oral gavage. In addition to performance parameters, intestinal contents were collected at 28 and 42 days of age for microbiota analysis by sequencing the 16s rRNA in V3 and V4 regions using the Illumina MiSeq platform. Taxonomy was assigned using the SILVA database (v. 138) with QIIME2 software (v. 2020.11). After one week of challenge, the broilers that received tylosin had a higher body weight gain (BWG) than those in the control group (p < 0.05), while the other treatments presented intermediate values. At 28 d, the BWG was lower for the control, CNSL-Castor oil 0.5 kg/t, enramycin, and virginiamycin treatments than that in the tylosin treatment. The inclusion of CNSL-Castor oil at concentrations of 0.75 and 1 kg/t acted as an intermediate treatment (p < 0.05). For alpha diversity, using the Shannon index, it was possible to observe the effect of age, with substantial diversity at 42 d. The Firmicutes phylum had the highest abundance, with values between 84.33% and 95.16% at 42 d. Tylosin showed better performance indices than other treatments. CNSL-castor oil treatments with concentrations of 0.75 and 1 kg/t showed similar results to those of enramycin and virginiamycin. Furthermore, CNSL-castor oil acted as a modulator of intestinal microbiota, reducing the abundance of pathogenic bacteria.

The possibility of a halal mix probiotic medium for the cultivation of Lactobacillus plantarum N16 and Saccharomyces cerevisiae

This study aimed to determine the effects of interaction between media type (halal mix preparation) and culture mixtures of Lactobacillus plantarum N16 and Saccharomyces cerevisiae (probiotics). A completely randomised factorial design (CRFD) consisting of 2 factors and three replications was used, where factor A was a mixture of Lactobacillus plantarum N16 and Saccharomyces cerevisiae at a ratio of 1:1 (A1); 1:2 (A2) and 2:1 (A3) and factor B was the type of growth media, that is, control (B1), whey tofu, molasses, and fish waste flour (B2), and coconut water, onggok flour and shrimp waste flour (B3). The variables measured were viability, cell biomass, and pH. The results showed interactions between factors A and B, which were significantly different (p <0.05) in terms of viability, cell biomass, and pH. Based on the results of the study, it can be concluded that the mixture of Lactobacillus plantarum N16 and Saccharomyces cerevisiae at a ratio of 2:1 (A3), using coconut water, onggok flour, and shrimp waste flour (B3) as medium and incubated at 36 °C for 24 hours was the best medium. It had a 2.37 viability, 42.33 mg/ml biomass cell, and a pH of 2.37.

Impact of Probiotics on Dairy Production Efficiency

There has been growing interest on probiotics to enhance weight gain and disease resistance in young calves and to improve the milk yield in lactating animals by reducing the negative energy balance during the peak lactation period. While it has been well established that probiotics modulate the microbial community composition in the gastrointestinal tract, and a probiotic-mediated homeostasis in the rumen could improve feed conversation competence, volatile fatty acid production and nitrogen flow that enhances the milk composition as well as milk production, detailed changes on the molecular and metabolic level prompted by probiotic feed additives are still not understood. Moreover, as living biotherapeutic agents, probiotics have the potential to directly change the gene expression profile of animals by activating the signalling cascade in the host cells. Various direct and indirect components of probiotic approaches to improve the productivity of dairy animals are discussed in this review.

Recent Advances in Probiotic Application in Animal Health and Nutrition: A Review

Biotechnological advances in animal health and nutrition continue to play a significant role in the improvement of animal health, growth, and production performance. These biotechnological advancements, especially the use of direct-fed microbials, also termed probiotics, those genetically modified and otherwise, have minimized many challenges facing livestock production around the world. Such advancements result in healthy animals and animal products, such as meat, for a growing population worldwide. Increasing demand for productivity, healthy animals, and consumer food safety concerns, especially those emanating from excessive use of antibiotics or growth promoters, are a driving force for investing in safer alternatives, such as probiotics. The advent of vastly diverse pathogens and bacterial organisms, some of which have acquired antimicrobial resistance due to therapeutic use of these antibiotics, has had a negative impact on the animal and food industries. Probiotics have been chosen as substitutes to counter this excessive use of antibiotics and antibiotic resistance. Over the last decade, probiotics have gained recognition, increased in importance, and stimulated growing interest in the animal health and nutrition industry. Probiotics are considered to be favorable live microorganisms by the host organism by maintaining microbial homeostasis and healthy gut, and can be a viable alternative to antibiotics in addition to providing other growth-promoting properties. Even though various studies describe the modes of action of probiotics, more research is needed to illuminate the exact mechanism of action of probiotics and how they benefit the host. This review describes the importance of probiotics in animal health, nutrition, and in growth and production performance. It also provides a thorough review of recent advances in probiotics research and application in animal health and nutrition and future directions on probiotic research to enhance animal performance.

Progress on Gut Health Maintenance and Antibiotic Alternatives in Broiler Chicken Production

The perturbation of gut health is a common yet unresolved problem in broiler chicken production. Antibiotics used as growth promoters have remarkably improved the broiler production industry with high feed conversion efficiency and reduced intestinal problems. However, the misuse of antibiotics has also led to the increase in the development of antibiotic resistance and antibiotic residues in the meat. Many countries have enacted laws prohibiting the use of antibiotics in livestock production because of the increasing concerns from the consumers and the public. Consequently, one of the most significant discussions in the poultry industry is currently antibiotic-free livestock production. However, the biggest challenge in animal husbandry globally is the complete removal of antibiotics. The necessity to venture into antibiotic-free production has led researchers to look for alternatives to antibiotics in broiler chicken production. Many strategies can be used to replace the use of antibiotics in broiler farming. In recent years, many studies have been conducted to identify functional feed additives with similar beneficial effects as antibiotic growth promoters. Attention has been focused on prebiotics, probiotics, organic acids, emulsifiers, enzymes, essential oils, tributyrin, and medium-chain fatty acids. In this review, we focused on recent discoveries on gut health maintenance through the use of these functional feed additives as alternatives to antibiotics in the past 10 years to provide novel insights into the design of antibiotic-free feeds.

Immunomodulatory and ameliorative effects of probiotic in combination with diclazuril on broilers under coccidia infection

AIM

This study aimed to determine the potential prophylactic efficacy of probiotic individually and/or in combination with anti-coccidial drug on the performance and immunity of broilers under an induced coccidial infection over a 28-day of experimental trial.

METHODS

One hundred and eighty 1-day-old Cobb broiler chicks were randomly divided into five groups, included control group (CG), control positive group (CPG), probiotic-treated group (Prob), diclazuril-treated group (Dic), and probiotic + diclazuril-treated group (Prob + Dic). On day 21 of age, all birds, except group CG, were orally inoculated with 1 ml of tap water containing 25,000 Eimeria tenella sporulated oocysts.

RESULTS

Our results showed that the probiotic treatment did not influence pre-challenge body weight, feed intake and feed conversion ratio (FCR). During the post-challenge period, chickens in groups probiotic and diclazuril individually and in combination exhibited higher body weight and lower (better) FCR, reduced oocyst shedding (throughout the day four, five, six and seven post-infection), cecal lesions and mortality compared with control positive chickens. Moreover, Compared to CPG group, Prob + Dic group showed increased (p < 0.05) serum levels of interleukin-10 (IL-10) and immunoglobulin M (IgM) and decreased the concentrations of interferon gamma (IFN-γ). On the other hand, individual treatment with probiotic exhibited highest serum levels of IL-10 and IgM, while diclazuril alone increased the blood concentrations of IL-10 and decreased the levels of IFN-γ compared to control positive group; however, there was no significant effect of Prob on IFN-γ, Dic on IgM and all groups on interleukin-17.

CONCLUSION

In conclusion, supplementation of probiotic, with and/or without anti-coccidial drug, enhances immunity and inhibits the negative effects of Eimeria infection.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reveals the anti-coccidial mechanisms of probiotic in the presence and absence of anti-coccidial drug in preventing the coccidia infection.

Clostridium butyricum Supplement Can Ameliorate the Intestinal Barrier Roles in Broiler Chickens Experimentally Infected With Clostridium perfringens

Necrotic enteritis (NE), caused by Clostridium perfringens, is an economically important disease in the broiler. Among normal flora in the broiler intestinal region, Clostridium butyricum has been identified as a probiotic agent that reduces the susceptibility of broilers to C. perfringens. However, the effects of C. butyricum supplement on broiler intestinal integrity during NE are largely unknown. In this study, we investigated the effects of C. butyricum on the growth performance, intestinal morphology and barrier function, and the functions of immune-related cytokines under NE in broilers. Chickens were divided into five groups: control group (NC), supplement C. butyricum only group (CB), NE-infected group (PC), supplement C. butyricum from Day 14 (NECB1) to Day 22 NE-infected group, and supplement C. butyricum from Day 1 (NECB2) to Day 22 NE-infected group. The results showed that there were significantly decreased average daily weight gain and increased feed conversion rate in the infected group (PC) compared with the C. butyricum-supplemented groups (NECB1 and NECB2) through the diet. Histopathological observation on the Hematoxylin–Eosin staining avian small intestine sections revealed that supplementation of C. butyricum (NECB1 and NECB2) could increase the intestinal villus height/crypt depth and lessen the intestinal damage under NE. ELISA and Limulus test showed that broilers infected with NE (PC) had higher serum IgA and lipopolysaccharide content; however, after C. butyricum supplementation (NECB1 and NECB2), they returned to a normal level. Furthermore, real-time PCR and Western blot results indicated that compared with PC, supplementing C. butyricum (NECB1 and NECB2) could initialize the expressions of genes related to the intestinal barrier-associated molecules (such as CLDN-1, CLDN-3, OCLN, MUC2, ZO-1, and CLDN5), cytokines (such as IL-10, IL-6, and TGFB1), and C. perfringens plc gene expression. Moreover, the results detected by the Ussing chamber suggested that C. butyricum (NECB1 and NECB2) could amend the decrease in conductivity value and short-circuit current value caused by NE. In addition, NECB2 significantly reduced the upregulation of fluorescein isothiocyanate–dextran flux caused by the NE disease. In conclusion, these findings suggest that dietary supplementation of C. butyricum in broilers with NE improved chicken growth performance, intestinal integrity and barrier function, and immunological status. Notably, no statistical difference was observed with the addition of C. butyricum on day 1 or day 14.

Controlling the causative agents of coccidiosis in domestic chickens; an eye on the past and considerations for the future

Coccidiosis is a potentially severe enteritis caused by species of obligate intracellular parasites of the genus Eimeria. These parasites cause significant economic losses to the poultry industry, predominantly due to compromised efficiency of production as well as the cost of control. These losses were recently estimated to cost chicken producers approximately £10.4 billion worldwide annually. High levels of Eimeria infection cause clinical coccidiosis which is a significant threat to poultry welfare, and a pre-disposing contributory factor for necrotic enteritis. Control of Eimeria parasites and coccidiosis is therefore an important endeavour; multiple approaches have been developed and these are often deployed together. This review summarises current trends in strategies for control of Eimeria, focusing on three main areas: good husbandry, chemoprophylaxis and vaccination. There is currently no "perfect solution" and there are advantages and limitations to all existing methods. Therefore, the aim of this review is to present current control strategies and suggest how these may develop in the future.

The Recent Trend in the Use of Multistrain Probiotics in Livestock Production: An Overview

It has been established that introducing feed additives to livestock, either nutritional or non-nutritional, is beneficial in manipulating the microbial ecosystem to maintain a balance in the gut microbes and thereby improving nutrient utilization, productivity, and health status of animals. Probiotic use has gained popularity in the livestock industry, especially since antimicrobial growth promoter's use has been restricted due to the challenge of antibiotic resistance in both animals and consumers of animal products. Their usage has been linked to intestinal microbial balance and improved performance in administered animals. Even though monostrain probiotics could be beneficial, multistrain probiotics containing two or more species or strains have gained considerable attention. Combining different strains has presumably achieved several health benefits over single strains due to individual isolates' addition and positive synergistic adhesion effects on animal health and performance. However, there has been inconsistency in the effects of the probiotic complexes in literature. This review discusses multistrain probiotics, summarizes selected literature on their effects on ruminants, poultry, and swine productivity and the various modes by which they function.

Protective Effect of Lactobacillus plantarum P8 on Growth Performance, Intestinal Health, and Microbiota in Eimeria-Infected Broilers

Coccidiosis is one of the major parasitic diseases in the commercial broiler industry. Probiotics can protect poultry against Eimeria infection. However, the mechanisms are not fully known. Therefore, Lactobacillus plantarum P8 (P8) was used to investigate its anti-coccidial property and mechanism. Five hundred broilers were allocated to five treatments: control diet (NC), control diet + Eimeria infection (IC), control diet containing 1 × 10⁷ cfu/g P8 + Eimeria infection (P8L), control diet containing 1 × 10⁸ cfu/g P8 + Eimeria infection (P8H), and control diet + Eimeria infection + Diclazuril (DIC). At day 14, all treatments except NC were inoculated with sporulated oocysts. Results indicated that Eimeria infection increased the mortality and oocysts shedding, and declined the growth performance as well as the intestinal barrier in Eimeria-treated broilers. On the contrary, dietary supplementation of low level P8, high level P8 and DIC decreased the mortality and oocysts shedding, but improved the growth performance and intestinal barrier. The impaired intestinal morphology in the IC group was also improved by P8H and DIC treatments. Besides, the elevated oxidative stress and pro-inflammation in Eimeria-infected broilers were reduced by P8L, P8H, and DIC treatments. Metagenomic analysis indicated P8 altered the structure of the gut microbiota, and the alteration was more obvious at day 21 than day 42. Notably, IC also increased the abundances of Eimeriidae, Eimeria and Eimeria tenella at day 21, while P8L and DIC decreased the abundances. Correlation analysis revealed that bacteria in Eimeria-treated broilers positively correlated with the intestinal permeability, oxidative stress and inflammation, while bacteria in broilers receiving P8L and DIC negatively correlated with the aforementioned pathological indices. Functional prediction demonstrated that the metagenomes of Eimeria-infected broilers were involved in several diseases. But the metagenomes of P8L-treated broilers were involved in energy metabolism and replication repair. In conclusion, dietary P8 supplementation inhibited oocyst shedding and improved the growth performance as well as the intestinal health of broilers infected with Eimeria, which was closely related to the regulation of gut microbiota. Moreover, the effects of P8 may be more effective in the early infection of coccidia.

Probiotics-Live Biotherapeutics: a Story of Success, Limitations, and Future Prospects-Not Only for Humans

In livestock production, lactic acid bacteria (LAB) represent the most widespread microorganisms used as probiotics. For such critical use, these bacteria must be correctly identified and characterized to ensure their safety and efficiency. Recently, probiotics have become highly recognized as supplements for humans and in particular for animals because of their beneficial outcome on health improvement and well-being maintenance. Various factors, encompassing dietary and management constraints, have been demonstrated to tremendously influence the structure, composition, and activities of gut microbial communities in farm animals. Previous investigations reported the potential of probiotics in animal diets and nutrition. But a high rate of inconsistency in the efficiency of probiotics has been reported. This may be due, in a major part, to the dynamics of the gastrointestinal microbial communities. Under stressing surroundings, the direct-fed microbials may play a key role as the salient limiting factor of the severity of the dysbiosis caused by disruption of the normal intestinal balance. Probiotics are live microorganisms, which confer health benefits on the host by positively modifying the intestinal microflora. Thus, the aim of this review is to summarize and to highlight the positive influence of probiotics and potential probiotic microbe supplementation in animal feed with mention of several limitations.

Transcriptome Analysis Revealed Ameliorative Effects of Bacillus Based Probiotic on Immunity, Gut Barrier System, and Metabolism of Chicken under an Experimentally Induced Eimeria tenella Infection

In this study, we performed transcriptome analysis in the cecum tissues of negative control untreated non-challenged (NC), positive control untreated challenged (PC), and Bacillus subtilis (B. subtilis) fed challenged chickens (BS + ET) in order to examine the underlying potential therapeutic mechanisms of Bacillus based probiotic feeding under an experimental Eimeria tenella (E. tenella) infection. Our results for clinical parameters showed that birds in probiotic diet decreased the bloody diarrhea scores, oocyst shedding, and lesion scores compared to positive control birds. RNA-sequencing (RNA-seq) analysis revealed that in total, 2509 up-regulated and 2465 down-regulated differentially expressed genes (DEGs) were detected in the PC group versus NC group comparison. In the comparison of BS + ET group versus PC group, a total of 784 up-regulated and 493 down-regulated DEGs were found. Among them, several DEGs encoding proteins involved in immunity, gut barrier integrity, homeostasis, and metabolism were up-regulated by the treatment of probiotic. Functional analysis of DEGs also revealed that some gene ontology (GO) terms related with immunity, metabolism and cellular development were significantly affected by the exposure of probiotic. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis showed that the DEGs in the cecum of B. subtilis-fed challenged group were mainly participated in the pathways related with immunity and gut barrier integrity, included mitogen-activated protein kinase (MAPK) signaling pathway, toll-like receptor (TLR) signaling pathway, extracellular matrix (ECM)–receptor interaction, tight junction, and so on. Taken together, these results suggest that Bacillus based probiotic modulate the immunity, maintain gut homeostasis as well as barrier system and improve chicken metabolism during E. tenella infection.

Comparative effect of papaya (Carica papaya) leaves' extract and Toltrazuril on growth performance, hematological parameter, and protozoal load in Sonali chickens infected by mixed Eimeria spp

Objective

Anticoccidial drugs may lead to the development of drug resistance and drug residues. Herbal extracts could be an attractive alternative. This research was undertaken to evaluate the anticoccidial outcome of Carica papaya compared with the anticoccidial drug (Toltazuril) in Sonali chickens.

Materials and Methods

A total of 80 Sonali chickens were evenly and equally allocated into four groups, namely T ₁ (non-infected control), T ₂ (infected control), T ₃ (treated with C. papaya), and T ₄ (treated with Toltrazuril). All groups were experimentally infected with oocysts of mixed Eimeria spp. orally except T ₁, and the mixed Eimeria spp. oocyst load (OL), body weight (BW) gain, and hematological parameters were calculated.

Results

In the findings, the highest OL reduction rate in T ₄ was 100%, while the T ₃ was 83.44%. Nevertheless, BW differed significantly (p < 0.01) among the different groups, while the daily BW gain was higher in T ₃ amounting to 8.10 gm. In the case of hematological parameter, total erythrocyte count (TEC), hemoglobin (Hb), packed cell volume (PCV), and erythrocyte sedimentation rate in different groups were almost the same and were also statistically insignificant (p > 0.05) barring total leukocyte count resulting as significant (p < 0.05) at day 30. Additionally, the results of Pearson's correlation in T ₃ at day 30 indicated a strong significant (p < 0.01) negative correlation between OL and BW (r = -0.780) with the following regression equation: y = -0.16*x + 433.665. Moreover, the correlation of TEC, PCV, and Hb with OL was significantly (p < 0.01) negative, r = -0.786, r = -0.752 and r = -0.633, where the regression equations were y = -0.03*x + 4.51, y = -0.03*x + 27.42, and y = -0.04*x + 11.40, respectively.

Conclusion

Long-term use of C. papaya leaves' extracts effectively controls coccidiosis in Sonali chickens and can act as an effective growth promoter.

Network meta-analysis comparing the effectiveness of anticoccidial drugs and anticoccidial vaccination in broiler chickens

With the trend to organic production and concerns about using antibiotic feed additives, the control of infections with Eimeria spp. in broiler flocks has become more difficult. Vaccination against coccidia is an alternative, but there are concerns that the live vaccines used might have negative effects on production parameters and intestinal health. Reports of experiments directly comparing anticoccidial drugs and anticoccidial vaccines are rare. This network meta-analysis (NMA) identified and analyzed 61 articles reporting 63 experiments testing anticoccidial drugs and anticoccidial vaccines under conditions resembling commercial broiler production. The effect sizes were mean differences in body weight/body weight gain (BW/BWG) and feed conversion rate (FCR) between the 175 included groups. The results show that groups vaccinated against coccidia have a similar BW/BWG and FCR at processing age compared to groups given anticoccidial drugs. However, the results tended to be more favorable for anticoccidial drugs than for vaccines. The analysis of eight subsets, containing only groups (1) groups that had not received an AGP in addition to an anticoccidial drug, (2) groups that had not received ionophores, (3) groups that had not received chemicals, (4) groups that had not received an attenuated vaccine, (5) groups that had not received a fully virulent vaccine, (6) groups that were not additionally challenged with bacteria or not challenged, (7) groups that had received a severe challenge as defined by a total infection dose of more than 100,000 oocysts or were not challenged, (8) groups that were challenged on day 15 or earlier or not challenged brought similar results and confirmed the robustness of the NMA. In addition, the analysis exposes unnecessary, as well as inherent, problems with data quality, which every researcher working with coccidia should carefully consider, and identifies under-researched areas that should be addressed in future research.

The use of probiotics in animal feeding for safe production and as potential alternatives to antibiotics

Although the production of safe food for human consumption is the primary purpose for animal rearing, the environment and well-being of the animals must also be taken into consideration. Based on microbiological point of view, the production of healthy food from animals involves considering foodborne pathogens, on the one hand and on the other hand, the methods used to fight against germs during breeding. The conventional method to control or prevent bacterial infections in farming is the use antibiotics. However, the banning of these compounds as growth promoters caused many changes in animal breeding and their use has since been limited to the treatment and prevention of bacterial infections. In this function, their importance no longer needs to be demonstrated, but unfortunately, their excessive and abusive use have led to a double problem which can have harmful consequences on consumer health: Resistance to antibiotics and the presence of antibiotic residues in food. The use of probiotics appears to be a suitable alternative to overcome these problems because of their ability to modulate the immune system and intestinal microflora, and further considering their antagonistic role against certain pathogenic bacteria and their ability to play the role of growth factor (sometimes associated with prebiotics) when used as feed additives. This review aims to highlight some of the negative effects of the use of antibiotics in animal rearing as well as emphasize the current knowledge on the use of probiotics as a feed additive, their influence on animal production and their potential utility as an alternative to conventional antibiotics, particularly in poultry, pig, and fish farming.

The Effects of Selenium-Enriched Probiotics on Growth Performance, Oocysts Shedding, Intestinal Cecal Lesion Scores, Antioxidant Capacity, and mRNA Gene Expression in Chickens Infected with Eimeria tenella

This study was carried out to investigate the effects of selenium-enriched probiotics (SP) supplementation on growth performance, oocysts shedding, intestinal lesions and antioxidant capacities, and mRNA gene expression of local Chinese yellow male chickens infected with Eimeria tenella. One-day-old 270 chickens were randomly assigned into five groups, each consisting of three replicates with 18 chickens per replicate. Chickens in the negative and positive controls (NC, PC, respectively) received basal diets only (0.11 mg Se/kg), whereas the other groups were supplied basal diets with probiotics and designated as (P, 0.11 mg Se/kg), sodium selenite (SS, 0.41 mg Se/kg), and (SP, 0.41 mg Se/kg) groups. At 21 days of age, except the NC group, all other groups were infected by oral gavage with 1.5 × 10⁴ sporulated E. tenella oocysts per chicken. Three chickens were randomly selected from each group for serum, liver, and cecal specimen collection. The results showed that P, SS, and SP had significant increase weight gain and feed intake. Additionally, these groups showed higher activities of serum superoxide dismutase (SOD) and glutathione peroxidase-1 (GPx1) compared to the PC group, whereas feed conversion ratio (FCR), serum catalase (CAT) activity, and malondialdehyde (MDA) content remained lower. Moreover, P, SS, and SP groups had lower oocyst shedding and cecal lesion scores. Significant upregulation of the glutathione peroxidase-1 (GPx1), glutathione peroxidase-4 (GPx4), Selenium W (SelW), and interferon gamma (IFN-γ) mRNA expression were detected in the SP group, which was then followed by SS when compared to the P group, whereas mRNA expression down-regulated in the PC group compared to NC, P, SS, and SP. In the NC and P groups, there were no significant differences in mRNA expression, except that IFN-γ mRNA level upregulated in P. We concluded that selenium-enriched probiotic supplementation has profound effects in enhancing the growth performance, antioxidant capacities, mRNA gene expression, reduced of oocysts shedding, and the cecal lesion scores of chickens and do provide protection against E. tenella.

Sustainable Antibiotic-Free Broiler Meat Production: Current Trends, Challenges, and Possibilities in a Developing Country Perspective

Simple Summary

Chickens are raised with the assistance of the regular use of antibiotics, not only for the prevention and treatment of diseases but, also, for body growth. Overuse and misuse of antibiotics in animals are contributing to the rising threat of antibiotic resistance. Therefore, antibiotic-free broiler meat production is becoming increasingly popular worldwide to meet consumer demand. However, numerous challenges need to be overcome in producing antibiotic-free broiler meat by adopting suitable strategies regarding food safety and chicken welfare issues. This review focuses on the current scenario of antibiotic use, prospects, and challenges in sustainable antibiotic-free broiler meat production. We also discuss the needs and challenges of antibiotic alternatives and provide a future perspective on antibiotic-free broiler meat production.

Abstract

Antibiotic-free broiler meat production is becoming increasingly popular worldwide due to consumer perception that it is superior to conventional broiler meat. Globally, broiler farming impacts the income generation of low-income households, helping to alleviate poverty and secure food in the countryside and in semi-municipal societies. For decades, antibiotics have been utilized in the poultry industry to prevent and treat diseases and promote growth. This practice contributes to the development of drug-resistant bacteria in livestock, including poultry, and humans through the food chain, posing a global public health threat. Additionally, consumer demand for antibiotic-free broiler meat is increasing. However, there are many challenges that need to be overcome by adopting suitable strategies to produce antibiotic-free broiler meat with regards to food safety and chicken welfare issues. Herein, we focus on the importance and current scenario of antibiotic use, prospects, and challenges in the production of sustainable antibiotic-free broiler meat, emphasizing broiler farming in the context of Bangladesh. Moreover, we also discuss the need for and challenges of antibiotic alternatives and provide a future outlook for antibiotic-free broiler meat production.

Influence of Eimeria spp. infection and dietary inclusion of arginine on intestine histological parameters, serum amino acid profile and ileal amino acids digestibility in broiler chicks

Coccidiosis is considered to be one of the most important challenge in the poultry industry causes economic losses due to the destruction in the digestive tract of chicken. It disturbs amino acids profile and their digestibility, leading to weight lost and economic burden. Using dietary arginine may decrease the adverse effects of coccidiosis on chicken digestive tract. This study aimed to evaluate the effects of dietary inclusion of arginine on intestine histological parameters, serum amino acid concentration and ileal amino acid digestibility of broiler chicks infected with coccidiosis. A total number of 384 one-d-old broiler chicks (Ross 308) of mixed sex with initial weight of 42 ± 2 g was allocated into 8 groups with 8 birds/pen from grower period. At 21 days of age, broiler chicks were infected with a mixture of Eimeria spp. Broiler chicks were divided into infected and un-infected groups and received arginine at recommended levels of 85, 100, 125 and 150 %. Intestinal morphology and lesions, serum amino acid concentration and ileal amino acid digestibility were evaluated. Broiler chicks infected with Eimeria spp. showed lower villus height and villus height: crypt depth ratio and also higher intestinal lesions (P < 0.05). Coccidia infection decreased the ileal amino acid digestibility for all studied amino acids and also reduced serum concentrations of amino acids, except lysine and isoleucine (P < 0.05). Dietary supplementation of arginine especially in higher levels significantly increased villus height and villus height:crypt depth ratio and decreased lesions (P < 0.05). Moreover, dietary supplementing of arginine increased the serum concentration of arginine (P < 0.05), but it did not have any significant effect on its digestibility (P > 0.05). In sum, coccidiosis decreases amino acid digestibility and serum amino acid concentration, but dietary inclusion of higher levels of arginine significantly improved histological parameters of broiler chicks infected with coccidiosis.

Modulation of the intestinal microbiota of broilers supplemented with monensin or functional oils in response to challenge by Eimeria spp

The objective of this study was to evaluate the effect of supplementation with 100ppm sodium monensin or 0.15% of a blend of functional oils (cashew nut oil + castor oil) on the intestinal microbiota of broilers challenged with three different Eimeria spp. The challenge was accomplished by inoculating broiler chicks with sporulated oocysts of Eimeria tenella, Eimeria acervulina, and Eimeria maxima via oral gavage. A total of 864, day-old male broiler chicks (Cobb) were randomly assigned to six treatments (eight pens/treatment; 18 broilers/pen) in a 3 × 2 factorial arrangement, composed of three additives (control, monensin or blend), with or without Eimeria challenge. Intestinal contents was collected at 28 days of age for microbiota analysis by sequencing 16s rRNA in V3 and V4 regions using the Illumina MiSeq platform. Taxonomy was assigned through the SILVA database version 132, using the QIIME 2 software version 2019.1. No treatment effects (p > 0.05) were observed in the microbial richness at the family level estimated by Chao1 and the biodiversity assessed by Simpson’s index, except for Shannon's index (p < 0.05). The intestinal microbiota was dominated by members of the order Clostridiales and Lactobacillales, followed by the families Ruminococcaceae, Bacteroidaceae, and Lactobacillaceae, regardless of treatment. When the controls were compared, in the challenged control group there was an increase in Erysipelotrichaceae, Lactobacillaceae, Bacteroidaceae, Streptococcaceae, and Peptostreptococcaceae, and a decrease in Ruminococcaceae. Similar results were found for a challenged group that received monensin, while the blend partially mitigated this variation. Therefore, the blend alleviated the impact of coccidiosis challenge on the microbiome of broilers compared to monensin.

Probiotic bacteria maintain normal growth mechanisms of heat stressed broiler chickens

Probiotics have growth promoting effects even under periods of heat stress challenge. More information is needed to understand the mechanisms by which probiotics maintain the growth performance. The aim of this study was to evaluate the effect of a probiotic based on Bacillus subtilis bacteria on growth related mechanisms of broilers under heat stress conditions. Specifically, growth performance, skeletal bone characteristics, skeletal muscles size, intestinal villus-crypt structure, intestinal bacteria, growth hormone (GH), insulin-like growth factor-1 (IGF-1), cholesterol, and glucose. A total of 1200 one day old Ross 308 male broilers were randomly distributed into 4 treatments, with 12 replicates per treatment and 25 birds per replicate. A 2 × 2 factorial arrangement was used; the main factors were environmental temperature (thermoneutral or heat stress) and diet (control or control + B. subtilis; 3 × 10⁷ cfu/kg of feed). From d 22 to 35 of age, birds were either exposed to thermoneutral conditions (21 °C) or chronic heat stress (30 °C). During the same period, each group was divided into 2 subgroups and fed either the control diet or the B. subtilis supplemented diet. The results demonstrated that B. subtilis had positive effects (P < 0.05) on the body weight gain, feed conversion ratio, villus height, crypt depth, villus surface area, absorptive epithelial cell area and viable counts of intestinal beneficial bacteria. B. subtilis increased (P < 0.05) serum GH, IGF-1 and maintain normal levels of cholesterol and glucose under heat stress conditions. In addition, broilers fed B. subtilis under heat stress conditions exhibited higher (P < 0.05) skeletal muscles size and improved (P < 0.05) tibia traits and lower (P < 0.05) abdominal fat pads deposition compared with the controls. B. subtilis had no effect on rectal temperature under thermoneutral or heat stress conditions. It is concluded that B. subtilis can be used as growth promoters in broilers, particularly during the periods of heat stress conditions.

Efficacy of probiotic Enterococcus faecium in combination with diclazuril against coccidiosis in experimentally infected broilers

AIMS

The study was conducted to investigate the combination of a probiotic strain of Enterococcus faecium and diclazuril to control coccidiosis in broilers.

METHODS AND RESULTS

A total of 240 one-day-old female broiler chicks were divided into eight groups (30 chicks per group): prophylactic groups (G1, G2 and G3) and therapeutic groups (G4, G5 and G6) and two control groups (untreated infected, G7 and untreated uninfected, G8 controls). In the prophylactic approach, diclazuril alone (G1), probiotic alone (G2) or a mixture of both probiotic and diclazuril (G3) was orally administered to the chicks via drinking water 10 days prior to the infection. However, in the therapeutic approach, G4, G5 and G6 birds were administered diclazuril alone, probiotic alone and diclazuril+probiotic mix, respectively, in drinking water for five consecutive days after the appearance of clinical signs of coccidiosis. Birds of both approaches and G7 were experimentally infected with 25 × 10³ Eimeria-sporulated oocysts. Chicks in G3 showed the highest weight gain, the lowest lesion score, a low oocyst count and mortality rate among the challenged groups. Moderate lesion scores and oocyst counts were observed in chickens administered probiotics prophylactically. In the therapeutic approach, broilers in G6 but not G5 displayed a decreased mortality rate and lesion score in comparison to those in G7 and G8. However, the result of the probiotic-treated group was not significantly different from that in the untreated infected control group.

CONCLUSION

The probiotic supplementation as a prophylactic approach can decrease the adverse effects of eimerian infection. In addition, the probiotic and diclazuril mix achieved a considerable improvement in the growth performance. Therefore, probiotic plus diclazuril combination achieved a synergistic effect.

SIGNIFICANCE AND IMPACT OF THE STUDY

Investigation into the synergism/antagonism between a probiotic and diclazuril as anticoccidial agent and the difference in the timing of administration.

Bacillus strains improve growth performance via enhancing digestive function and anti-disease ability in young and weaning rex rabbits

Numerous studies have shown that probiotic Bacillus could promote growth and enhance anti-disease ability in animal. In present study, the mixture of three Bacillus strains, which were isolated from rex rabbits and showed high cellulose, protease, and amylase activities, was added into the diet for investigating its effects on young and weaning rex rabbits. For experiment 1, 40 young rex rabbits (9 weeks old) were randomly divided into four groups and fed with diets containing 0 (NC), 1.0 × 10⁵ cfu/g (LC), 1.0 × 10⁶ cfu/g (MC), and 1.0 × 10⁷ cfu/g (HC) Bacillus strains for 4 weeks. For experiment 2, 80 weaning rex rabbits (5 weeks old) were randomly divided into four groups and fed with diet containing 0 (control), 1.0 × 10⁵ cfu/g (T-1), 1.0 × 10⁶ cfu/g (T-2), and 1.0 × 10⁷ cfu/g (T-3) Bacillus strains for 8 weeks. The results showed that Bacillus strains at a dose of 1.0 × 10⁶ cfu/g significantly enhanced growth performance, increased immune organ indexes, improved serum biochemical parameters, and heightened antioxidant capacity. It also markedly improved the intestinal microbiota by increasing Lactobacillus spp., Bacillus spp. counts, and decreased Escherichia coli count. In addition, the Bacillus mixture raised the concentrations of acetic acid, propionic acid, and butyric acid as well as protease, amylase, and cellulase activities of young and weaning rex rabbits. Moreover, for weaning rex rabbits, the inclusion of Bacillus strains also upregulated the abundance of cellulolytic bacteria and improved intestinal morphology. Therefore, our results indicated that Bacillus strains could facilitate the growth of young and weaning rex rabbits by improving digestive function and anti-disease ability. KEY POINTS: • Bacillus with high extracellular enzyme activity were isolated from rex rabbits. • Bacillus could improve growth performance of young and weaning rex rabbits. • The digestive function of young and weaning rex rabbits could be improved by Bacillus.

Protective effects of a food-grade recombinant Lactobacillus plantarum with surface displayed AMA1 and EtMIC2 proteins of Eimeria tenella in broiler chickens

Background

Avian coccidiosis posts a severe threat to poultry production. In addition to commercial attenuated vaccines, other strategies to combat coccidiosis are urgently needed. Lactobacillus plantarum has been frequently used for expression of foreign proteins as an oral vaccine delivery system using traditional erythromycin resistance gene (erm). However, antibiotic selection markers were often used during protein expression and they pose a risk of transferring antibiotic resistance genes to the environment, and significantly restricting the application in field production. Therefore, a food-grade recombinant L. plantarum vaccine candidate would dramatically improve its application potential in the poultry industry.

Results

In this study, we firstly replaced the erythromycin resistance gene (erm) of the pLp_1261Inv-derived expression vector with a non-antibiotic, asd-alr fusion gene, yielding a series of non-antibiotic and reliable, food grade expression vectors. In addition, we designed a dual-expression vector that displayed two foreign proteins on the surface of L. plantarum using the anchoring sequences from either a truncated poly-γ-glutamic acid synthetase A (pgsA′) from Bacillus subtilis or the L. acidophilus surface layer protein (SlpA). EGFP and mCherry were used as marker proteins to evaluate the surface displayed properties of recombinant L. plantarum strains and were inspected by western blot, flow cytometry and fluorescence microscopy. To further determine its application as oral vaccine candidate, the AMA1 and EtMIC2 genes of E. tenella were anchored on the surface of L. plantarum strain. After oral immunization in chickens, the recombinant L. plantarum strain was able to induce antigen specific humoral, mucosal, and T cell-mediated immune responses, providing efficient protection against coccidiosis challenge.

Conclusions

The novel constructed food grade recombinant L. plantarum strain with double surface displayed antigens provides a potential efficient oral vaccine candidate for coccidiosis.

Dissection of the cecal microbial community in chickens after Eimeria tenella infection

Background

Eimeria spp. are responsible for chicken coccidiosis which is the most important enteric protozoan disease resulting in tremendous economic losses in the poultry industry. Understanding the interaction between the avian cecal microbiota and coccidia is of interest in the development of alternative treatments that do not rely on chemotherapeutics and do not lead to drug resistance.

Methods

We utilized 16S rRNA gene sequencing to detect the dynamics of the cecal microbial community in AA broilers challenged with Eimeria tenella. Histopathological analysis of the cecum was also conducted.

Results

We found that microbial shifts occur during the infection. Lactobacillus, Faecalibacterium, Ruminococcaceae UCG-013, Romboutsia and Shuttleworthia decreased in abundance. However, the opportunistic pathogens Enterococcus and Streptococcus increased in abundance over time in response to the infection.

Conclusions

Eimeria tenella disrupts the integrity of the cecal microbiota and could promote the establishment and growth of potentially pathogenic bacteria. Defining bacterial populations affected by coccidial infection might help identify bacterial markers for intestinal disease as well as populations or species that could be beneficial in maintaining and restoring gut homeostasis during and after infection with E. tenella.