In ovo supplementation of probiotics and its effects on performance and immune-related gene expression in broiler chicks

In-ovo injection of Bacillus subtilis, raffinose, and their combinations enhances hatchability, gut health, nutrient transport- and intestinal function-related genes, and early development of broiler chicks

An experiment was conducted to assess the response of chicks to in-ovo injection of Bacillus subtilis (probiotic), raffinose (prebiotic), and their combinations. The study used 1,500 embryonated eggs allotted to 10 groups/ 6 replicates (150 eggs/group). The experimental treatments were: 1) un-injected control (NC); 2) sham (sterile distilled water) (PC); 3) probiotic 4 × 105CFU/egg (LBS); 4) probiotic 4 × 106CFU/egg (HBS); 5) prebiotic 2 mg/egg (LR); (6 prebiotic 3 mg/egg (HR); 7) probiotic 4 × 105CFU + prebiotic 2 mg/egg (LBS+LR); 8) probiotic 4 × 105CFU + prebiotic 3 mg/egg (LBS+HR); 9) probiotic 4 × 106CFU + prebiotic 2 mg/egg (HBS+LR); and 10) probiotic 4 × 106CFU + prebiotic 3 mg/egg (HBS+HR). Results showed that in-ovo inclusion of Bacillus subtilis, prebiotic, and their combinations improved hatchability, yolk-free chick weight, and chick weight compared to the control group. Moreover, the in-ovo treatment reduced residual yolk weight on the day of hatch compared to the control group. Different levels of in-ovo B. subtilis alone or combined with raffinose significantly (P ≤ 0.001) reduced total bacterial count and total yeast and mold count compared to the negative control group. Total coliform and E. coli decreased significantly (P ≤ 0.001) in groups treated with probiotics, prebiotics, and synbiotics with different doses during incubation compared to those in the control. Clostridium spp. was not detected in the groups injected with B. subtilis alone or combined with raffinose. In-ovo probiotics and synbiotics (LBS+LR & LBS+HR) significantly (P ≤ 0.001) increased ileal villus length compared to other groups. In-ovo treatment increased mRNA expression of JAM-2 compared to the control group. The fold change significantly increased in group LBS+HR for genes MUC-2, OCLN, VEGF, SGLT-1, and EAAT-3 compared to the negative control. In conclusion, in-ovo injection of a low dose of B. subtilis plus a high or low dose of raffinose can positively affect hatching traits, cecal microbial populations, intestinal histomorphometry, nutrient transport- and intestinal function-related genes, and chick quality of newly hatched broiler chicks.

Interplay of poultry-microbiome interactions - influencing factors and microbes in poultry infections and metabolic disorders

1. The poultry microbiome and its stability at every point in time, either free range or reared under different farming systems, is affected by several environmental and innate factors. The interaction of the poultry birds with their microbiome, as well as several inherent and extraneous factors contribute to the microbiome dynamics. A poor understanding of this could worsen poultry heath and result in disease/metabolic disorders.2. Many diseased states associated with poultry have been linked to dysbiosis state, where the microbiome experiences some perturbation. Dysbiosis itself is too often downplayed; however, it is considered a disease which could lead to more serious conditions in poultry. The management of interconnected factors by conventional and emerging technologies (sequencing, nanotechnology, robotics, 3D mini-guts) could prove to be indispensable in ensuring poultry health and welfare.3. Findings showed that high-throughput technological advancements enhanced scientific insights into emerging trends surrounding the poultry gut microbiome and ecosystem, the dysbiotic condition, and the dynamic roles of intrinsic and exogenous factors in determining poultry health. Yet, a combination of conventional, -omics based and other techniques further enhance characterisation of key poultry microbiome actors, their mechanisms of action, and roles in maintaining gut homoeostasis and health, in a bid to avert metabolic disorders and infections.4. In conclusion, there is an important interplay of innate, environmental, abiotic and biotic factors impacting on poultry gut microbiome homoeostasis, dysbiosis, and overall health. Associated infections and metabolic disorders can result from the interconnected nature of these factors. Emerging concepts (interkingdom or network signalling and neurotransmitter), and future technologies (mini-gut models, cobots) need to include these interactions to ensure accurate control and outcomes.

Modulation of gene expression in immune-related organs by in ovo stimulation with probiotics and prophybiotics in broiler chickens

In ovo stimulation has been studied intensively as an alternative to antibiotic use in poultry production. We investigated the potential use of a probiotic in combination with a phytobiotic as a prophybiotic for in ovo stimulation and reported its beneficial effects on the gut microbiome of broiler chickens. The current study further investigates the gene expression in the immune-related organs of these chickens to understand the tissue-specific immunomodulatory effects of the treatments. The selected prophybiotic (Leuconostoc mesenteroides with garlic aqueous extract) and its probiotic component alone were injected into ROSS308 chicken eggs on the 12th day of incubation, and gene expression in cecal tonsils, spleen, and liver at 35 days of age was determined using qPCR method. The relative expression of each treatment was compared to the positive control, chickens injected with physiological saline in ovo. The results displayed a downregulation of pro- and anti-inflammatory cytokines in the cecal tonsils of the probiotic group and the liver of the prophybiotic group. The spleen displayed upregulated AVBD1 in both groups and upregulated IL1-β in the probiotic group. The probiotic group displayed increased expression of genes related to metabolism of energy (COX16), protein (mTOR), and lipids (CYP46A1) whereas the prophybiotic group displayed reduced expression of genes related to cholesterol synthesis (SREBP1) and glucose transportation (SLC2A2) in the liver. In conclusion, Leuconostoc mesenteroides differentially modulated gene expression in chickens when administered in ovo in combination with garlic aqueous extract. Further in ovo studies with different prophybiotic combinations are required to optimize the benefits in broiler chickens.

In ovo probiotic supplementation supports hatchability and improves hatchling quality in broilers

In modern broilers, the period of embryonic development constitutes a greater proportion of a broiler's productive life. Hence, optimum embryonic development can exert a significant influence not only on chick hatchability and hatchling quality but also on overall broiler growth and performance. Further healthy and active hatchlings are correlated with improved posthatch performance. In this regard, probiotics are good candidates to mediate early-life programming. Therefore, we evaluated the effect of In ovo probiotic spray application on broiler hatchability and hatchling quality. The experiment was set out as a completely randomized study with 2 independent trials. In each trial, 540 eggs (Ross 308) were either sprayed with phosphate buffered saline (PBS; control) or probiotics [∼9 log CFU/egg of Lactobacillus rhamnosus NRRL B-442(LR) or Lactobacillus paracasei DUP 13076 (LP)] during incubation. On day 18, eggs were transferred to the hatcher and set up for hatching. Starting on day 19, eggs were observed for hatching to determine the spread of hatch and hatchability. Hatched chicks were then assessed for quality using the Tona and Pasgar score and morphometric measurements including hatchling weight, yolk-free-body-mass and hatchling length were measured. Further, chicks were reared in floor pens for 3 wk to assess posthatch growth. Overall, In ovo probiotic supplementation improved hatchability and hatchling quality. Specifically, the spray application of LP improved hatchability by ∼ 5% without affecting the spread of hatch. Further, both LR and LP significantly improved Pasgar and Tona score, indicating an improvement in hatchling quality. Also, LP and LR significantly improved hatchling weight, yolk-free-body-mass, and posthatch growth in chicks. LR significantly improved hatchling weight and hatchling length (P < 0.05). Moreover, this increase in posthatch growth was positively correlated with hatchling weight in the probiotic groups. Overall, our study demonstrates that In ovo probiotic application exerts a positive effect on hatchability, hatchling quality, and subsequent posthatch growth.

Supplemental effect of Pediococcus acidilactici CNCM I-4622 probiotic on the laying characteristics and calcium and phosphorus metabolism in laying hens

The close link between intestinal microbiota and bone health ('gut-bone' axis) has recently been revealed: the modulation of the amount and nature of bacteria present in the intestinal tract has an impact on bone health and calcium (Ca) metabolism. Probiotics are known to favorably impact the intestinal microbiota. The objective of this study was to investigate the effect of Pediococcus acidilactici CNCM I-4622 (PA) on laying performance, egg/eggshell quality, Ca metabolism and bone mineralization and resistance in relatively old layers (50 wks old at the beginning of the experiment) during 14 weeks. 480 Hy Line brown layers were divided into 2 groups (CON and PA: 3 layers/rep, 80 rep/group) and fed with a diet formulated to be suboptimal in calcium (Ca) and phosphorus (P) (- 10% of the requirements). The total egg weight was improved by 1.1% overall with PA, related to an improvement of the weight of marketable eggs (+ 0.9%). PA induced a decreased % of downgraded eggs, mainly broken eggs (- 0.4 pts) and FCR improvement (- 0.8% for all eggs, - 0.9% for marketable eggs). PA also led to higher Haugh units (HU: + 7.4%). PA tended to decrease crypt depth after the 14 weeks of supplementation period in the jejunum (- 25.2%) and ileum (- 17.6%). As a consequence, the VH/CD ratio appeared increased by PA at the end of the trial in the jejunum (+ 63.0%) and ileum (+ 48.0%). Ca and P retention were increased by 4 pts following PA supplementation, translating into increased bone hardness (+ 19%), bone cohesiveness (+ 43%) and bone Ca & P (+ 1 pt) for PA-supplemented layers. Blood Ca and P were respectively improved by 5% and 12% with PA. In addition, blood calcitriol and osteocalcin concentrations were respectively improved by + 83% and + 3% in PA group at the end of the trial, compared to CON group. There was no difference between the 2 groups for ALP (alkaline phosphatase) and PTH (parathyroid hormone). PA significantly decreased the expression of the following genes: occludin in the small intestine, calbindin 1 in the ovarian tissue and actin B in the bone. PA therefore improved zootechnical performance of these relatively old layers, and egg quality. The parallel increase in Ca and P in the blood and in the bone following PA supplementation suggests an improvement of the mineral supply for eggshell formation without impacting bone integrity, and even increasing bone resistance.

Biophysiology of in ovo administered bioactive substances to improve gastrointestinal tract development, mucosal immunity, and microbiota in broiler chicks

Early embryonic exogenous feeding of bioactive substances is a topic of interest in poultry production, potentially improving gastrointestinal tract (GIT) development, stimulating immunization, and maximizing the protection capability of newly hatched chicks. However, the biophysiological actions and effects of in ovo administered bioactive substances are inconsistent or not fully understood. Thus, this paper summarizes the functional effects of bioactive substances and their interaction merits to augment GIT development, the immune system, and microbial homeostasis in newly hatched chicks. Prebiotics, probiotics, and synbiotics are potential bioactive substances that have been administered in embryonic eggs. Their biological effects are enhanced by a variety of mechanisms, including the production of antimicrobial peptides and antibiotic responses, regulation of T lymphocyte numbers and immune-related genes in either up- or downregulation fashion, and enhancement of macrophage phagocytic capacity. These actions occur directly through the interaction with immune cell receptors, stimulation of endocytosis, and phagocytosis. The underlying mechanisms of bioactive substance activity are multifaceted, enhancing GIT development, and improving both the innate and adaptive immune systems. Thus summarizing these modes of action of prebiotics, probiotics and synbiotics can result in more informed decisions and also provides baseline for further research.

Factors influencing the development of gastrointestinal tract and nutrient transporters' function during the embryonic life of chickens-A review

Intestinal morphology and regulation of nutrient transportation genes during the embryonic and early life of chicks influence their body weight and feed conversion ratio through the growing period. The intestine development can be monitored by measuring villus morphology and enzymatic activity and determining the expression of nutrient transporters genes. With the increasing importance of gut development and health in broiler production, considerable research has been directed towards factors affecting intestine development. Thus, this article reviews (1) intestinal development during embryogenesis, and (2) maternal factors, in ovo administration, and incubation conditions that influence intestinal development during embryogenesis. Conclusively, (1) chicks from heavier eggs may have a better-developed intestine than chicks from younger ones, (2) in ovo supplementation with amino acids, minerals, vitamins or a combination of several probiotics and prebiotics stimulates intestine development and increases the expression of intestine mucosal-related genes and (3) the long storage period, improper incubation temperature and imbalanced ventilation can negatively influence intestinal morphology and nutrient transporters gene expression. Finally, understanding the intestine development during embryonic life will enable us to enhance the productivity of broilers.

Effect of In Ovo Administration of a Multi-Strain Probiotic and Zinc Glycine Chelate on Antioxidant Capacity and Selected Immune Parameters in Newly Hatched Chicks

The aim of this study was to determine the effect of in ovo co-supplementation of chicken embryos with a multi-strain probiotic containing effective microorganisms and zinc glycine chelate on total antioxidant capacity; concentrations of sulfhydryl groups, bityrosine bridges, formylkynurenines, hydroperoxides, proteins, corticosterone, pro- and anti-inflammatory cytokines and heat shock proteins; and the activity of catalase and superoxide dismutase in the serum, yolk sac and tissues of broiler chickens at 12 h and at 7 days after hatching. The results indicate high SOD activity in the small and large intestines of chicks at 12 h post-hatch in the groups receiving the multi-strain probiotic and in the small intestine and yolk sac of birds receiving the multi-strain probiotic and Zn-Gly chelate. High concentrations of TNF-α and IFN-γ in the yolk sac and serum after in ovo administration of Zn-Gly chelate were observed 12 h after hatching. The use of a probiotic and a probiotic with Zn-Gly chelate increased the total antioxidant capacity in the tissues of chickens. It can be concluded that in ovo administration of a multi-strain probiotic and Zn-Gly chelate can maintain the oxidant/antioxidant balance in chickens and increase the defense capacity against oxidative stress.

Effect of combined in ovo administration of zinc glycine chelate (Zn-Gly) and a multistrain probiotic on the modulation of cellular and humoral immune responses in broiler chickens

The aim of the study was to determine the effect of in ovo administration of zinc glycine chelate (Zn-Gly), and a multistrain probiotic on the hatchability and selected parameters of the cellular and humoral immune response of chickens. The study was conducted on 1,400 fertilized eggs from commercial broiler breeders (Ross x Ross 708). Material for the study consisted of peripheral blood and spleens of chicks taken 12 h and 7 d after hatching. The results showed that both combined and single in ovo administration of the multistrain probiotic and zinc glycine chelate significantly reduced hatchability of chicks. The flow cytometry study showed that the highest percentage of CD4+ T cells, CD4+CD25+, and high expression of KUL01 in the serum were obtained in the group supplemented with probiotic and Zn-Gly both 12 h and 7 d after hatching. In birds supplemented with probiotic and zinc chelate, a high percentage of TCRγδ+ cells was found in serum and spleen 12 h after hatching and in serum after 7 d. The percentage of Bu-1A+ lymphocytes in serum and spleen 12 h and 7 d after hatching was the highest in the group supplemented with probiotic and Zn-Gly. The highest expression of CD79A was observed in the group supplemented only with zinc chelate. There were no significant differences in the percentage of CD4+ cells in the spleens of birds in the groups receiving the multistrain probiotic at 12 h after hatching, and after 7 d, the percentage of CD4+ T cells was lower in the experimental groups than in the control group. The percentage of CD8+ cells in the serum of birds after hatching was lower in the group supplemented with multistrain probiotic and Zn-Gly than in the control group, but reached the highest value on d 7 after hatching. The obtained results confirm the strong effect of the combined administration of a multistrain probiotic and Zn-Gly chelate on lymphocyte proliferation and stimulation of cellular immune mechanisms in birds.

An Attempt of a New Strategy in PRV Prevention: Co-Injection with Inactivated Enterococcus faecium and Inactivated Pseudorabies Virus Intravenously

Pseudorabies virus (PRV) is one of the causative agents of common infectious diseases in swine herds. Enterococcus faecium is a probiotic belonging to the group of lactic acid bacteria and has excellent immunomodulatory effects. Vaccine immunization is an important approach to prevent animal diseases in the modern farming industry, and good immunization outcomes can substantially reduce the damage caused by pathogens to animals, improve the quality of animals' lives, and reduce economic losses. In the present study, we showed that inactivated E. faecium and inactivated PRV when co-injected intravenously significantly reduced the mortality of mice after inoculation with PRV. The inactivated E. faecium + inactivated PRV intravenous injection group induced more production of Th cells and Tc cells. Additionally, the inactivated E. faecium + inactivated PRV intravenous injection group showed higher concentrations of cytokines (IFN-γ and IL-10) and induced higher antibody production. Thus, the co-injection of inactivated E. faecium and inactivated PRV could remarkably prevent and control the lethality of PRV infection in mice, which is a critical finding for vaccination and clinical development.

Physiological effects of in ovo delivery of bioactive substances in broiler chickens

The poultry industry has improved genetics, nutrition, and management practices, resulting in fast-growing chickens; however, disturbances during embryonic development may affect the entire production cycle and cause irreversible losses to broiler chicken producers. The most crucial time in the chicks' development appears to be the perinatal period, which encompasses the last few days of pre-hatch and the first few days of post-hatch. During this critical period, intestinal development occurs rapidly, and the chicks undergo a metabolic and physiological shift from the utilization of egg nutrients to exogenous feed. However, the nutrient reserve of the egg yolk may not be enough to sustain the late stage of embryonic development and provide energy for the hatching process. In addition, modern hatchery practices cause a delay in access to feed immediately post-hatch, and this can potentially affect the intestinal microbiome, health, development, and growth of the chickens. Development of the in ovo technology allowing for the delivery of bioactive substances into chicken embryos during their development represents a way to accommodate the perinatal period, late embryo development, and post-hatch growth. Many bioactive substances have been delivered through the in ovo technology, including carbohydrates, amino acids, hormones, prebiotics, probiotics and synbiotics, antibodies, immunostimulants, minerals, and microorganisms with a variety of physiological effects. In this review, we focused on the physiological effects of the in ovo delivery of these substances, including their effects on embryo development, gastrointestinal tract function and health, nutrient digestion, immune system development and function, bone development, overall growth performance, muscle development and meat quality, gastrointestinal tract microbiota development, heat stress response, pathogens exclusion, and birds metabolism, as well as transcriptome and proteome. We believe that this method is widely underestimated and underused by the poultry industry.

Lactobacillus (L. plantarum & L. rhamnosus) and Saccharomyces (S. cerevisiae): effects on performance, biochemical parameters, ammonium ion in manure, and digestibility of broiler chickens

Two strains of Lactobacillus combined with Baker's yeast (Saccharomyces cerevisiae) used as probiotics were evaluated to replace antibiotics in poultry flocks by reducing ammonia emissions in manure of broilers without comprising performance or health. One-day-old Cobb 500 broilers (600) were fed starter, grower, and finisher diets as control (CON); probiotic S. cerevisiae, inclusion rate at 4.26 × 10⁶ CFU/kg of feed (SCY); probiotic L. plantarum and L. rhamnosus, inclusion rate at 4.35 × 10⁸ CFU/kg of feed (LPR) for each; and a combination of Lactobacillus plantarum and L. rhamnosus at 4.35 × 10⁸ CFU/kg of feed for each plus Saccharomyces cerevisiae and 4.26 × 10⁶ CFU/kg of feed (SWL). The 4 treatments had 5 replicates (pens), each with 30 broilers. Performance was measured weekly as feed consumption, weight gain, BW, and feed conversion ratio (FCR) over a 6-wk grow-out period. Accompanying biochemical analyses included lipase activity of the pancreas, liver weight, and uric acid (UA) concentration in liver. Albumin, total protein, UA, ammonia, and blood urea nitrogen (BUN) were measured in serum. Ammonium (NH₄⁺) in manure and apparent ileal digestibility from digesta were also measured. Significance was determined at P ≤ 0.05. Results showed that biochemical analyses had no significant treatment effect; however, there were significant temporal changes in performance measures for individual treatments. Feed consumption increased over time for all treatments (P = 2.00 × 10^-16). CON had lower weight gain in wk 2 (P = 0.013) compared to all treatment and the lowest BW in wk 5 (P = 0.0008) and wk 6 (P = 0.0124) compared to SWL. Specific probiotic strains, with well-defined inclusion rates, and surrounding environmental analyses of present microbes are needed to ascertain effects of probiotics. Other important areas for investigation include 1) confirmation of probiotics present in the digesta/ceca and how they alter the microbiota within the gastrointestinal (GI) tract and 2) the serum heterophil:lymphocyte ratio to further examine potential immune responses to the probiotics.

The effect of Bacillus subtilis and its delivery route on hatch and growth performance, blood biochemistry, immune status, gut morphology, and microbiota of broiler chickens

This study evaluated the effect of probiotics (Bacillus subtilis fermentation extract) and its delivery route (in-feed or in ovo) on hatch and growth performance, blood biochemistry, immune status, gut morphology, and microbiota of broiler chickens. Hatching eggs were incubated for 21 d. On d 12, viable eggs were randomly allotted to 4 groups: the noninjected, in ovo saline (S), in ovo Bacillus subtilis 1 (P1), and in ovo Bacillus subtilis 2 (P2). On d 18, S, P1, and P2 groups received 0.2 mL saline diluent, 10 × 10⁶, and 20 × 10⁶ CFU of the bacterium via the amnion, respectively. At hatch, chicks were re-allotted to 5 new treatment groups: P1, P2, 0.005% in-feed Bacillus subtilis extract (P3), 0.05% in-feed bacitracin methylene disalicylate (BMD,), and corn-wheat-soybean diet negative control (NC) in 9 replicate pens (22 birds/pen) and raised for 35 d. Hatch parameters were assessed on d 0, and growth performance indices measured weekly. On d 25, 1 bird/cage was euthanized, and samples collected for further analysis. Data were analyzed by generalized linear model. Treatments S and P2 recorded higher (P = 0.01) chick BW/ Egg Weight values compared to the non-injected eggs. P3 and P2 reduced (P = 0.02) FI at week 5 compared to the NC treatment. However, no change in average body weight gain (ABG) and feed conversion ratio (FCR) were observed during the same period. At d 35, while BMD treatment showed a tendency (P = 0.09) to increase FI compared to the NC treatment, ABG and FCR were similar for all treatments. Blood sodium and chloride levels were increased (P < 0.05) by the BMD treatment compared to the NC treatment. Compared to other treatments, BMD and P3 treatments increased (P < 0.001) jejunal and ileal villus height to crypt depth ratios, respectively. However, P1 and P2 increased (P < 0.001) villus height to crypt depth ratio in the duodenum compared to NC treatment. Treatments did not affect gut microbial diversity; however, BMD treatment increased (P < 0.05) the proportion of bacteria in the genus Enterococcus in the ileum and reduced (P < 0.05) the proportion of bacteria in the genus Streptococcus in the ceca. All probiotics treatments (irrespective of route and dose) reduced (P < 0.001) the levels of serum IgG compared to the NC treatment. However, P1 and P2 had the lowest numerical decrease in serum IgG concentrations, suggesting that Bacillus subtilis (especially in ovo delivered) might provide broiler chickens with better immunological protection by neutralizing pathogenic organisms that could result in the production of natural antibodies.

Embryonic modulation through thermal manipulation and in ovo feeding to develop heat tolerance in chickens

Healthy chickens are necessary to meet the ever-increasing demand for poultry meat. Birds are subjected to numerous stressful conditions under commercial rearing systems, including variations in the environmental temperature. However, it is difficult to counter the effects of global warming on the livestock industry. High environmental temperature is a stressful condition that has detrimental effects on growth and production performance, resulting in decreased feed intake, retarded growth, compromised gut health, enhanced oxidative stress, and altered immune responses. Traditional approaches include nutritional modification and housing management to mitigate the harmful effects of hot environments. Currently, broiler chickens are more susceptible to heat stress (HS) than layer chickens because of their high muscle mass and metabolic rate. In this review, we explored the possibility of in ovo manipulation to combat HS in broiler chickens. Given their short lifespan from hatching to market age, embryonic life is thought to be one of the critical periods for achieving these objectives. Chicken embryos can be modulated through either temperature treatment or nourishment to improve thermal tolerance during the rearing phase. We first provided a brief overview of the harmful effects of HS on poultry. An in-depth evaluation was then presented for in ovo feeding and thermal manipulation as emerging strategies to combat the negative effects of HS. Finally, we evaluated a combination of the two methods using the available data. Taken together, these investigations suggest that embryonic manipulation has the potential to confer heat resistance in chickens.

Assessment of the effect of kinetin against formic acid toxicity in chicken embryo model

The current study was designed to investigate the in ovo injection of formic acid (FA) on hatchability rate (HR; Experiment 1) and the potential ameliorative role of kinetin concurrent with FA on biochemical parameters of hatched broilers (Experiment 2). In Experiment 1, live embryonated eggs (n = 280; Day 4 of incubation) were in ovo injected with 0.03, 0.06, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16 and 32 m m FA. In Experiment 2, intra-yolk-sac administration of toxic doses of FA (2 m m) concurrent with kinetin at 50, 100 or 200 µ m were evaluated on hatched embryos. The amount of malondialdehyde (MDA), total antioxidant capacity (TAC), total nitrate-nitrite (TNN), total lipid hydroperoxide (TLHP) and superoxide dismutase (SOD) activity was measured in serum, liver, heart and brain tissues. The results revealed that injection of 2 mM FA significantly increased mortality compared to the control group (p < 0.05). Concurrent administration of 50 or 100 µ m kinetin + 2 m m FA increased HR to 10% and 20% compared to the FA-alone-treated group, respectively. Intra-yolk-sac-received FA group showed greater amounts of MDA, TLHP and TNN and lesser amounts of TAC and SOD activity in serum and tissue samples of liver, heart and brain compared to control groups (p < 0.001). In comparison to the FA-alone-treated group, all doses of kinetin were able to increase the TAC levels in serum and tissue samples when administered concurrently with FA. The doses of 50 and 100 µ m kinetin were efficacious to ameliorate the toxic role of FA injection on SOD activities (p < 0.001). Co-injection of 100 µ m kinetin plus FA significantly reduced the amounts of MDA, TNN and TLHP in measured samples compared to the FA-alone-injected group (p < 0.001). Our results indicated that kinetin (especially at 100 µ m doses) would ameliorate the toxic effects of FA on developing live chicken embryos.

Early life environment affects behavior, welfare, gut microbiome composition, and diversity in broiler chickens

This study aimed to identify whether early-life conditions in broiler chickens could affect their behavior and welfare, and whether or not this was associated with an altered gut microbiome composition or diversity. Broilers were tested in a 2 x 2 factorial design with hatching conditions [home pen (OH) or at the hatchery (HH)] and enrichment (dark brooder (EE) or no brooder (NE) until 14 days of age) as factors (N = 6 per treatment combination). Microbiota composition was measured in the jejunum on days (d) 7, 14, and 35 and in pooled fecal samples on day 14. A novel environment test (NET) was performed on days 1 and 11, and the behavior was observed on days 6, 13, and 33. On day 35, composite asymmetry was determined and footpad dermatitis and hock burn were scored. In their home pen, HH showed more locomotion than OH (P = 0.05), and NE were sitting more and showed more comfort behavior than EE at all ages (P <0.001 and P = 0.001, respectively). On days 6 and 13 NE showed more eating and litter pecking while sitting, but on day 33 the opposite was found (age^*enrichment: P = 0.05 and P <0.01, respectively). On days 1 and 11, HH showed more social reinstatement in the NET than OH, and EE showed more social reinstatement than NE (P <0.05). Composite asymmetry scores were lower for EE than NE (P <0.05). EE also had less footpad dermatitis and hock burn than NE (P <0.001). Within OH, NE had a more diverse fecal and jejunal microbiome compared to EE on day 14 (feces: observed richness: P = 0.052; jejunum: observed richness and Shannon: P <0.05); the principal component analysis (PCA) showed differences between NE and EE within both HH and OH in fecal samples on day 14, as well as significant differences in bacterial genera such as Lactobacillus and Lachnospiraceae (P <0.05). On day 35, PCA in jejunal samples only showed a trend (P = 0.068) for differences between NE vs. EE within the OH. In conclusion, these results suggest that especially the dark brooder affected the behavior and had a positive effect on welfare as well as affected the composition and diversity of the microbiome. Whether or not the behavior was modulated by the microbiome or vice versa remains to be investigated.

Effect of in ovo administration of Newcastle disease vaccine conjugated with Astragalus polysaccharide on growth performance, intestinal development, and mucosal immunity in broiler chickens

This study was conducted to investigate the effect of in ovo administration of a mixture of Astragalus polysaccharide (APS) and Newcastle disease vaccine (NDV) on growth performance, intestinal development, and mucosal immunity in newly hatched chicks. Six hundred specific-pathogen-free (SPF) Leghorn fertilised eggs were incubated in a commercial hatchery and divided into four groups: (a) control group injected with 1 ml of 0.9% physiological saline, (b) APS group injected with 1 ml of 1 mg/ml APS solution, and (c) NDV group injected with 1 ml of 10^4.0 EID₅₀ /dose of NDV solution, and (d) APS + NDV group injected with a mixture of 0.5 ml of 2 mg/ml APS plus 0.5 ml 10^4.0 EID₅₀ /dose ND vaccine (NDV) on Day 18.5 of incubation. The results showed that in ovo injection of APS or the mixture of APS and NDV increased the body weight at 1 day (IW) and final weight (FW) at 28 days and increased the feed conversion ratio (FCR) at 1-7, 8-14, 15-21, and 1-28 days of age. The villus height (VH) was increased (p < 0.05), and the crypt depth (CD) was decreased (p < 0.05) in the duodenum compared with the control group. The VH/CD ratios were increased (p < 0.05) in the APS + NDV group compared with controls, NDV group, and APS group on d3. The levels of slgA in washings were increased (p < 0.05) on Days 3, 7, 14, 21, and 28, and the number of IgA⁺ cells in the duodenum was increased on Days 7, 14, 21, and 28. In addition, the IgA⁺ cells were promoted from the villus root to the apex in the APS + NDV group. It can be concluded that in ovo administration of NDV conjugated with APS compared with NDV alone may be more effective in promoting growth performance and intestinal mucosal immunity.

Recent developments in antimicrobial growth promoters in chicken health: Opportunities and challenges

With a continuously increasing human population is an increasing global demand for food. People in countries with a higher socioeconomic status tend to switch their preferences from grains to meat and high-value foods. Their preference for chicken as a source of protein has grown by 70% over the last three decades. Many studies have shown the role of feed in regulating the animal gut microbiome and its impact on host health. The microbiome absorbs nutrients, digests foods, induces a mucosal immune response, maintains homeostasis, and regulates bioactive metabolites. These metabolic activities are influenced by the microbiota and diet. An imbalance in microbiota affects host physiology and progressively causes disorders and diseases. With the use of antibiotics, a shift from dysbiosis with a higher density of pathogens to homeostasis can occur. However, the progressive use of higher doses of antibiotics proved harmful and resulted in the emergence of multidrug-resistant microbes. As a result, the use of antibiotics as feed additives has been banned. Researchers, regulatory authorities, and managers in the poultry industry have assessed the challenges associated with these restrictions. Research has sought to identify alternatives to antibiotic growth promoters for poultry that do not have any adverse effects. Modulating the host intestinal microbiome by regulating dietary factors is much easier than manipulating host genetics. Research efforts have led to the identification of feed additives, including bacteriocins, immunostimulants, organic acids, phytogenics, prebiotics, probiotics, phytoncides, and bacteriophages. In contrast to focusing on one or more of these alternative bioadditives, an improved feed conversion ratio with enhanced poultry products is possible by employing a combination of feed additives. This article may be helpful in future research towards developing a sustainable poultry industry through the use of the proposed alternatives.

In ovo Inoculation of Bacillus subtilis and Raffinose Affects Growth Performance, Cecal Microbiota, Volatile Fatty Acid, Ileal Morphology and Gene Expression, and Sustainability of Broiler Chickens (Gallus gallus)

Banning antibiotic growth promoters has negatively impacted poultry production and sustainability, which led to exploring efficient alternatives such as probiotics, probiotics, and synbiotics. Effect of in ovo injection of Bacillus subtilis, raffinose, and their synbiotics on growth performance, cecal microbial population and volatile fatty acid concentration, ileal histomorphology, and ileal gene expression was investigated in broilers (Gallus gallus) raised for 21 days. On 300 h of incubation, a total of 1,500 embryonated eggs were equally allotted into 10 groups. The first was non-injected (NC) and the remaining in ovo injected with sterile distilled water (PC), B. subtilis 4 × 10⁵ and 4 × 10⁶ CFU (BS1 and BS2), Raffinose 2 and 3 mg (R1 and R2), B. subtilis 4 × 10⁵ CFU + raffinose 2 mg (BS1R1), B. subtilis 4 × 10⁵ CFU + raffinose 3 mg (BS1R2), B. subtilis 4 × 10⁶ CFU + raffinose 2 mg (BS2R1), and B. subtilis 4 × 10⁶ CFU + raffinose 3 mg (BS2R2). At hatch, 60 chicks from each group were randomly chosen, divided into groups of 6 replicates (10 birds/replicate), and fed with a corn–soybean-based diet. In ovo inoculation of B. subtilis and raffinose alone or combinations significantly improved body weight, feed intake, and feed conversion ratio of 21-day-old broilers compared to NC. Cecal concentrations of butyric, pentanoic, propionic, and isobutyric acids were significantly elevated in R1, R2, BS2R1, and BS2R2, whereas isovaleric and acetic acids were significantly increased in R1 and BS2R1 compared to NC. Cecal microbial population was significantly altered in treated groups. Ileal villus height was increased (p < 0.001) in BS1, R2, and BS2R2 compared to NC. The mRNA expression of mucin-2 was upregulated (p < 0.05) in synbiotic groups except for BS1R1. Vascular endothelial growth factor (VEGF) expression was increased (p < 0.05) in BS2, R1, BS1R1, and BS1R2 compared to NC. SGLT-1 expression was upregulated (p < 0.05) in all treated birds except those of R1 group compared to NC. The mRNA expressions of interleukin (IL)-2 and toll-like receptor (TLR)-4 were downregulated (p < 0.05) in BS2 and R1 for IL-2 and BS1R1 and BS2R2 for TLR-4. It was concluded that in ovo B. subtilis, raffinose, and synbiotics positively affected growth performance, cecal microbiota, gut health, immune responses, and thus the sustainability of production in 21-day-old broilers.

In ovo co-administration of vitamins (A and D) and probiotic lactobacilli modulates immune responses in broiler chickens

There is evidence that probiotic lactobacilli, in addition to essential vitamins, such as vitamin A and D, have immunomodulatory properties that enhance immune response of neonatal chickens against infections. The present study evaluated the effects of in ovo administration of retinoic acid (RA), 25-Hydroxyvitamin D3 (VitD), and a lactobacilli cocktail on cytokine gene expression, antibody responses and spleen cell subsets in chickens. RA (90 µmol/egg) and VitD (0.6 μg/egg) were administered in ovo, either alone or in combination with lactobacilli (107 CFU/egg), at embryonic d 18. On d 5 and 10 posthatch, gene expression and cellular composition were analyzed in the bursa of Fabricius and spleen. Birds were immunized on d 14 and 21 posthatch with 2 T-dependent antigens, sheep red blood cells (SRBC) and keyhole limpet hemocyanin (KLH), to assess their antibody responses. Sera were collected from the immunized chickens on d 14, 21, 28, and 35 posthatch. The results demonstrated that lactobacilli treatment increased the number of monocyte/macrophages (KUL01+) and CD3+CD4+ T cells in the spleen, and enhanced serum anti-KLH IgM and IgY on d 14 postprimary immunization (P < 0.05). RA significantly increased serum IgY and IgM titers to KLH and enhanced the expression of interferon (IFN)-α, interleukin (IL)-1β, IL-6, IL-8, IL-12, IL-13, and transforming growth factor-β (TGF-β) in the bursa of Fabricius (P < 0.05). The percentage of CD3+CD8+ T cells, and monocyte/macrophages (KUL01+) was elevated in the spleen as well (P < 0.05). These findings reveal that prehatch administration of RA improves immunocompetency of neonatal chickens by increasing the production of cytokines that regulate innate immunity and through enhancing antibody-mediated response against T-dependent antigens.

Probiotics: Symbiotic Relationship with the Animal Host

Antibiotic growth-promoters in animal feeding are known to generate bacterial resistance on commercial farms and have proven deleterious effects on human health. This review addresses the effects of probiotics and their symbiotic relationship with the animal host as a viable alternative for producing healthy meat, eggs, and milk at present and in the future. Probiotics can tolerate the conditions of the gastrointestinal tract, such as the gastric acid, pH and bile salts, to exert beneficial effects on the host. They (probiotics) may also have a beneficial effect on productivity, health and wellbeing in different parameters of animal performance. Probiotics stimulate the native microbiota (microbes that are present in their place of origin) and production of short-chain fatty acids, with proven effects such as antimicrobial, hypocholesterolemic and immunomodulatory effects, resulting in better intestinal health, nutrient absorption capacity and productive responses in ruminant and non-ruminant animals. These beneficial effects of probiotics are specific to each microbial strain; therefore, the isolation and identification of beneficial microorganisms, as well as in vitro and in vivo testing in different categories of farm animals, will guarantee their efficacy, replicability and sustainability in the current production systems.

Non-Antibiotics Strategies to Control Salmonella Infection in Poultry

Salmonella spp. is a facultative intracellular pathogen causing localized or systemic infections, involving economic and public health significance, and remains the leading pathogen of food safety concern worldwide, with poultry being the primary transmission vector. Antibiotics have been the main strategy for Salmonella control for many years, which has allowed producers to improve the growth and health of food-producing animals. However, the utilization of antibiotics has been reconsidered since bacterial pathogens have established and shared a variety of antibiotic resistance mechanisms that can quickly increase within microbial communities. The use of alternatives to antibiotics has been recommended and successfully applied in many countries, leading to the core aim of this review, focused on (1) describing the importance of Salmonella infection in poultry and the effects associated with the use of antibiotics for disease control; (2) discussing the use of feeding-based (prebiotics, probiotics, bacterial subproducts, phytobiotics) and non-feeding-based (bacteriophages, in ovo injection, vaccines) strategies in poultry production for Salmonella control; and (3) exploring the use of complementary strategies, highlighting those based on -omics tools, to assess the effects of using the available antibiotic-free alternatives and their role in lowering dependency on the existing antimicrobial substances to manage bacterial infections in poultry effectively.

Managing Gut Microbiota through In Ovo Nutrition Influences Early-Life Programming in Broiler Chickens

The chicken gut is the habitat to trillions of microorganisms that affect physiological functions and immune status through metabolic activities and host interaction. Gut microbiota research previously focused on inflammation; however, it is now clear that these microbial communities play an essential role in maintaining normal homeostatic conditions by regulating the immune system. In addition, the microbiota helps reduce and prevent pathogen colonization of the gut via the mechanism of competitive exclusion and the synthesis of bactericidal molecules. Under commercial conditions, newly hatched chicks have access to feed after 36-72 h of hatching due to the hatch window and routine hatchery practices. This delay adversely affects the potential inoculation of the healthy microbiota and impairs the development and maturation of muscle, the immune system, and the gastrointestinal tract (GIT). Modulating the gut microbiota has been proposed as a potential strategy for improving host health and productivity and avoiding undesirable effects on gut health and the immune system. Using early-life programming via in ovo stimulation with probiotics and prebiotics, it may be possible to avoid selected metabolic disorders, poor immunity, and pathogen resistance, which the broiler industry now faces due to commercial hatching and selection pressures imposed by an increasingly demanding market.

Effects of in ovo Injection of Astragalus Polysaccharide on the Intestinal Development and Mucosal Immunity in Broiler Chickens

The purpose of this study was to examine the effects of in ovo injection of Astragalus polysaccharide (APS) on hatchability, body weight (BW), intestinal histomorphology, the number of IgA⁺ cells and sIgA content in intestine, and the expression of intestinal immune-related genes in broiler chickens. On day 18 of the incubation, a total of 960 live embryo eggs were weighed and randomly divided into 4 treatment groups: a control group and three APS groups. The eggs in the control group were injected with 0.5 mL physiological saline. The eggs in the APS groups were injected with 3 different amounts of APS in 0.5 mL physiological saline: 1 mg (APS_L), 2 mg (APS_M) and 4 mg (APS_H). The solution was injected into the amnion of each egg. The results showed that in ovo injection of APS did not affect the hatchability but increased the body weight of the 14 d and 21 d chickens, with a significant increase observed in the APS_M group (P < 0.05). At most time points, the villus height (VH) was increased (P < 0.05) and the crypt depth (CD) was decreased (P < 0.05) in the small intestine of the broilers, with higher VH/CD ratios in the APS_L and APS_M groups compared with the control group. The number of IgA⁺ cells in the mucosa and the secretory immunoglobulin A (sIgA) levels in the intestinal washings were higher in the APS_M and APS_H groups than in the APS_L and control groups. The gene expression levels of interleukin (IL)-2, interleukin (IL)-4, interferon gamma (IFN-γ), and Toll-like receptor (TLR)-4 were significantly enhanced by APS stimulation at most time points (P < 0.05). These results indicated that in ovo injection of APS has the potential of promoting intestinal development and enhancing intestinal mucosal immunity of broiler chickens in the early stage after hatching.

Effects of zinc dosage and particle size on gut morphology, tight junctions and TNF-α expression in broiler breeder hens

This study was performed to evaluate the effects of different amounts and particle size of zinc oxide (ZnO) on villus height (VH), villus width (VW), crypt depth (CD) and VH to CD ratio (VH: CD), and expression of zonula occludens-1 (ZO-1), occludin (OC) and tumour necrosis factor-α (TNF-α) in broiler breeders. A total of 350 (Ross 308) broiler breeder hens of 54 weeks randomly assigned to seven treatments, included control basal diet (C) without added Zn, C+ 100, and 130 mg Zn per kg of diet from Large (L) (100-1000 nm) and Small (S) (<100 nm) particle size ZnO (LZnO100 and 130; SZnO100 and 130), C and SZnO100 challenged with lipopolysaccharide (C+LPS and SZnO100+LPS). Each diet was fed to five replicates consisting of ten birds each. The middle part of the duodenum, jejunum and ileum was used for morphological assessments. To assess the gene expression of ZO-1, OC and TNF-α in the jejunum samples were excised. Results showed that the supplementing 130 ppm SZnO increased VH:CD in the duodenum (p < 0.05). VW in the duodenum and all the evaluated morphometric indices in jejunum and ileum were not affected by the dietary treatment (p > 0.05). ZO-1 mRNA abundance in C+LPS group compared to SZnO100+LPS group was significantly decreased and increased by LPS and SZnO100 respectively. The SZnO-100 increased OC gene expression in compare to C+LPS group. The expression of TNF-α in C+LPS treatment was higher than other groups (p < 0.05). The lowest and the highest litter moisture and foot-pad dermatitis (FPD) were observed in LZnO-130 and C treatments respectively (p < 0.05). Improving the physical properties of ZnO affect on VH:CD. Broiler breeder diet with ZnO enhance ZO-1, OC and mitigate TNF-α gene expression in jejunum maintenance of gut health in broiler breeders.

Effects of Lactobacillus acidophilus on the growth performance, immune response, and intestinal barrier function of broiler chickens challenged with Escherichia coli O157

We studied the effects of Lactobacillus acidophilus (L. acidophilus) on the growth performance, intestinal morphology, barrier function, and immune response of broilers challenged with Escherichia coli O157 (E. Coli). A total of 360 1-day-old Cobb male broilers were tested in a 3 × 2 factorial arrangement with 3 dietary L. acidophilus levels (0, 5 × 108 CFU/kg, and 10 × 108 CFU/kg of diet) and 2 disease challenge treatments (control or E. coli challenged). Results showed that E. coli challenge decreased the ADG, ADFI, and BW of broilers from 15 to 21 d (P < 0.05), increased the jejunum intestinal wall thickness, and significantly increased the mortality rate. E. coli challenge significantly (P < 0.05) decreased the serum IgA and IgM contents and peripheral blood CD3+ T cell counts (P < 0.05), increased the serum CRP, DAO, and LPS levels at 21 d; upregulated the mRNA expression of iNOS, IL-8, IL-1β in the jejunum and iNOS in the spleen, and downregulated the occludin and ZO-1 mRNA expression in the ileum at 21 d compared with uninfected birds (P < 0.05). Dietary L. acidophilus supplementation consistently showed higher BW, ADG, ADFI, and jejunum and ileum V:C ratio at 14 d and 21 d in the presence and absence of E. coli challenge (P < 0.05). L. acidophilus supplementation reduced the mortality rate caused by E. coli challenge (P < 0.05), decreased the serum CRP, DAO, and LPS levels at 14 d and 21 d; upregulated the mRNA expression of occludin and ZO-1 in the jejunum and ileum, and downregulated the mRNA expression of iNOS, IL-8, and IL-1β in the jejunum in E. coli challenged birds at 21 d (P < 0.05). Dietary supplementation with L. acidophilus can improve the growth performance, intestinal health, and survival of broilers challenged with E. coli.

Probiotic Paenibacillus polymyxa 10 and Lactobacillus plantarum 16 enhance growth performance of broilers by improving the intestinal health

With the ever-growing strict prohibitions on antibiotic growth promoters (AGP) in animal production, in-feed probiotics are becoming attractive alternatives to antibiotics in the poultry industry. To investigate the effects of Paenibacillus polymyxa 10 and Lactobacillus plantarum 16 on the growth performance and intestinal health of broilers, 540 male Cobb 500 broilers of 1 d old were randomly divided into 3 groups with 6 replicates per group and 30 chicks per replicate. Broilers were fed with either a basal diet or basal diets supplemented with 1 × 108 colony-forming units (CFU)/kg P. polymyxa 10 (BSC10) or L. plantarum 16 (Lac16) for 42 d. Results showed that Lac16 treatment improved (P < 0.05) the growth performance (body weight and feed conversion) of broilers at the starter phase, while BSC10 treatment slightly improved (P > 0.05) the growth performance of the starter phase broilers. The increased villus height (P < 0.05) at d 14, 21 and 42 and villus height to crypt depth ratio (P < 0.05) at d 14 and 21 were observed in the ileum of the 2 probiotic groups. Besides, transmission electron microscopy results showed that the 2 probiotics enhanced the intestinal epithelial barrier. Both probiotic treatments up-regulated (P < 0.05) the mRNA expression of fatty acid binding protein 1 (FABP1) and sodium-dependent glucose transporters-1 (SGLT-1) in the ileal mucosa of broilers at d 21. In addition, BSC10 and Lac16 treatments significantly (P < 0.05) increased the relative abundance of short-chain fatty acids-producing bacteria, such as Butyricicoccus pullicaecorum, Faecalibacterium prausnitzii, Lachnospira and Coprococcu, and significantly (P < 0.05) decreased the relative abundance of enteric pathogens (Escherichia coli, Bacteroides fragilis and Shigella sonnei). Furthermore, the 2 probiotic treatments also increased the positive connection among the intestinal microbes and the carbohydrate metabolism-related pathways of the intestinal bacteria (P < 0.05), with decreasing (P < 0.05) nucleotides biosynthesis-related pathways of the intestinal bacteria. Overall, these results suggest that the 2 probiotics, especially Lac16, have a potential beneficial effect on the growth performance and intestinal health of starter phase broilers.

Effect of in ovo feeding of probiotic, prebiotic and synbiotic to Broiler embryos on growth performance, Mucin-2 gene expression and gut colonization of microbiota

Supplementation of antibiotics in poultry diet was banned in several countries due to development of antibiotic resistance. In ovo feeding of prebiotics, probiotics and synbiotics have gained more attention recently. The present study was carried out in 2018 to investigate the effect of in-ovo feeding of probiotic, prebiotic and symbiotic on growth performance and gut microbiome of broiler chicken. On 18th day of incubation, 600 eggs were randomly divided into five treatments each with four replicates of 30 eggs each and were injected with different bio-active compounds, viz. 0.2 ml of Lactobacillus acidophilus 3×107 cfu, 0.5% Mannan-oligosaccharide (MOS), synbiotic (0.1 ml each of Lactobacillus acidophilus 3×107 cfu and 0.5% MOS) along with injected and non-injected controls. After hatch, 400 chicks were sorted out as per treatment with four replicates of 20 chicks each. Birds were reared under deep litter system and fed with experimental diet ad lib. In ovo feeding of Lactobacillus acidophilus, MOS either separately or in combination significantly improved hatch weight, fifth week body weight and gain. However, hatchability, cumulative feed intake, cumulative FCR and cumulative livability were not affected. Improved colonization of Lactobacillus acidophilus and suppressed colonization of Salmonella, Escherichia coli and Staphylococcus in all intra-amniotic groups was noticed. Ileal Mucin-2 gene was significantly up-regulated in the order of MOS, L. acidophilus and synbiotic injected broilers. The results concluded that the in ovo delivery of Lactobacillus acidophilus and MOS either separately or in combination had beneficial effect on growth and gut health of broiler chicken.

Assessment of In Ovo Administration of Bifidobacterium bifidum and Bifidobacterium longum on Performance, Ileal Histomorphometry, Blood Hematological, and Biochemical Parameters of Broilers

Bifidobacterium is one of the most promising probiotics which was recently used as an alternative growth promoter in poultry. This trial was considered to evaluate the potential effects of in ovo administration of Bifidobacterium bifidum and Bifidobacterium longum on growth performance and biochemical parameters of broilers. Three hundred broiler breeder eggs were incubated and candled individually at day 17 of embryogenesis; then, eggs that had live embryos were randomly divided into six groups. The first and second groups were of intact (without injection) and vehicle-injected (sterile distilled water) control groups, respectively. Other groups were in ovo injected with 1 × 10⁹ and 1 × 10⁷ CFU B. bifidum, and 1 × 10⁹ and 1 × 10⁷ CFU B. longum, respectively. Hatchability was significantly (P < 0.001) affected by in ovo inoculation of bifidobacteria strains. Body weight gain and feed conversion ratio were significantly improved (P = 0.014 and 0.019, respectively) in all treatment groups. Protein fractions, aspartate aminotransferase, and alanine aminotransferase activities were not significantly altered by bifidobacteria strains in ovo injection. Regarding ileal histomorphometry parameters, a significant elevation in villus height and villus height/crypt depth ratio values were recorded while crypt depth was insignificantly affected by in ovo treatments. It could be concluded that the tested manual method of in-yolk sac injection at day 17 of incubation is more favorable in easier delivering of bifidobacteria strains which improve broiler growth performance and ileal development without any undesirable effects on blood indices and liver and renal functions.

The Effects of In Ovo Injection of Synbiotics on the Early Growth Performance and Intestinal Health of Chicks

In this study, the effects of synbiotic inclusion at the intra-amniotic stage in layer chicks were evaluated with different parameters, such as performance, immunological function, intestinal development, and cecal microflora content. A total of 1,200 eggs with fertile embryos were allocated into four treatment groups. For every treatment, five replicates were used, and 60 eggs were included in each replicate. The following four treatment groups were established: the non-injected group, 0.9% physiological saline injection (saline) group, 1 × 10⁶ CFU/egg Lactobacillus plantarum injection (probiotic) group, and 1 × 10⁶ CFU/egg L. plantarum + 2 mg/egg Astragalus polysaccharide injection (synbiotic) group. In ovo injection was carried out at 18.5 days of incubation. The results showed that in ovo injection of probiotics or synbiotics did not affect the hatching or growth performance of the chicks but significantly increased their feed intake (FI), body weight (BW), and the feed conversion ratio (FCR). Additionally, in ovo injection of synbiotics enhanced the levels of serum interleukin-2 (IL-2), interferon-γ (IFN-γ), and secretory immunoglobulin A (SIgA) in intestinal lavage fluid and the histomorphological development of the small intestine. Our results also indicated that intra-amniotic synbiotic injection significantly increased Lactobacillus and Bifidobacterium colonization while decreasing the relative abundance of Escherichia coli in the chicken cecum (P < 0.05). In summary, in ovo injection of synbiotics had positive impacts on the performance, immunological function, gut development, and microbiota of growing chicks.

Metabolome and Microbiota Analysis Reveals the Conducive Effect of Pediococcus acidilactici BCC-1 and Xylan Oligosaccharides on Broiler Chickens

Xylan oligosaccharides (XOS) can promote proliferation of Pediococcus acidilactic BCC-1, which benefits gut health and growth performance of broilers. The study aimed to investigate the effect of Pediococcus acidilactic BCC-1 (referred to BBC) and XOS on the gut metabolome and microbiota of broilers. The feed conversion ratio of BBC group, XOS group and combined XOS and BBC groups was lower than the control group (P < 0.05). Combined XOS and BBC supplementation (MIX group) elevated butyrate content of the cecum (P < 0.05) and improved ileum morphology by enhancing the ratio of the villus to crypt depth (P < 0.05). The 16S rDNA results indicated that both XOS and BBC induced high abundance of butyric acid bacteria. XOS treatment elevated Clostridium XIVa and the BBC group enriched Anaerotruncus and Faecalibacterium. In contrast, MIX group induced higher relative abundance of Clostridiaceae XIVa, Clostridiaceae XIVb and Lachnospiraceae. Besides, MIX group showed lower abundance of pathogenic bacteria such as Campylobacter. Metabolome analysis showed that all the 3 treatment groups (XOS, BBC and MIX) showed lower concentrations of sorbitol and both XOS and BBC group had higher concentrations of pyridoxine levels than CT group. Besides, XOS and BBC groups enhanced the content of hydroxyphenyl derivatives 4-hydroxyphenylpyruvate 1 and 3-(3-hydroxyphenyl) propionic acid, respectively (P < 0.05). Notably, MIX group enhanced both 4-hydroxyphenylpyruvate 1 and 3-(3-hydroxyphenyl) propionic acid (P < 0.05). Thus, XOS and BBC may have a synergistic role to improve the performance of broilers by modulating gut microbiota and metabolome.

In Ovo and Oral Administration of Probiotic Lactobacilli Modulate Cell- and Antibody-Mediated Immune Responses in Newly Hatched Chicks

There is some evidence that lactobacilli can strengthen the immune system of chickens. This study evaluated the effects of in ovo and oral administration of a lactobacilli cocktail on cytokine gene expression, antibody-mediated immune responses, and spleen cellularity in chickens. Lactobacilli were administered either in ovo at embryonic day 18, orally at days 1, 7, 14, 21, and 28 post-hatches, or a combination of both in ovo and post-hatch inoculation. On day 5 and 10 post-hatch, spleen and bursa of Fabricius were collected for gene expression and cell composition analysis. On days 14 and 21 post-hatch, birds were immunized with sheep red blood cells (SRBC) and keyhole limpet hemocyanin (KLH), and sera were collected on days 7, 14, and 21 post-primary immunization. Birds that received lactobacilli (107 CFU) via in ovo followed by weekly oral administration showed a greater immune response by enhancing antibody responses, increasing the percentage of CD4+ and CD4+CD25+ T cells in the spleen and upregulating the expression of interferon (IFN)-α, IFN-β, interleukin (IL)-8, IL-13, and IL-18 in the spleen and expression of IFN-γ, IL-2, IL-6, IL-8, IL-12, and IL-18 in the bursa. These findings suggest that pre-and post-hatch administration of lactobacilli can modulate the immune response in newly hatched chickens.

Effects of administration of probiotic lactobacilli on immunity conferred by the herpesvirus of turkeys vaccine against challenge with a very virulent Marek's disease virus in chickens

Several vaccines have been used to control Marek's disease (MD) in chickens. However, the emergence of new strains of Marek's disease virus (MDV) imposes a threat to vaccine efficacy. Therefore, the current study was carried out to investigate whether concurrent administration of probiotics with the herpesvirus of turkeys (HVT) vaccine enhances its protective efficacy against MDV infection. In this regard, a cocktail comprised of four Lactobacillus species was administered with HVT to chicken embryos at embryonic day 18 (ED18) and/or from day 1 to day 4 post-hatch. The results revealed that the administration of a probiotic Lactobacillus with HVT at ED18 followed by oral gavage with the same lactobacilli cocktail to newly hatched chicks for the first 4 days post-hatch increased the expression of major histocompatibility complex (MHC) II on macrophages and B cells in spleen and decreased the number of CD4⁺CD25⁺ T regulatory cells in the spleen. Subsequently, chicks were infected with MDV. The chickens that received in ovo HVT and lactobacilli or HVT had higher expression of IFN-α at 21dpi in the spleen compared to the chickens that were challenged with MDV. Also, the expression of IFN-β in cecal tonsils at 10dpi was higher in the groups that received in ovo HVT and lactobacilli and oral lactobacilli compared to the group that received in ovo HVT alone. Moreover, the expression of tumor growth factor (TGF)-β4 at 4 days post-infection was reduced in the group that received both HVT and probiotics at ED18. Additionally, concurrent probiotics administration reduced tumor incidence by half when compared to HVT vaccine alone indicating enhancing effect of lactobacilli with HVT vaccine on host immune responses. In conclusion, these findings suggest the potential use of probiotic lactobacilli as adjuvants with the HVT vaccine against MDV infection in chickens.

In ovo administration of Bacillus subtilis serotypes effect hatchability, 21-day performance, and intestinal microflora

Recent research has tried to maximize broiler chick health and performance by utilizing commercial in-feed probiotics to inoculate fertile hatching eggs, and thus expose birds earlier to beneficial bacteria. However, the in ovo inoculation of a specific serotype of Bacillus subtilis was detrimental for broiler hatchability. Therefore, the objective of this study was to determine if other B. subtilis serotypes negatively affect hatchability or if it is associated with a specific serotype. It was also of interest to determine if the B. subtilis serotype influence chick performance and intestinal microflora. On d18 of incubation, 1886 fertile broiler eggs were in ovo inoculated with the following treatments (T): T1 = Marek's vaccine (MV), T2 = MV + B. subtilis (ATCC 6051), T3 = MV + B. subtilis (ATCC 8473), and T4 = MV + B. subtilis (ATCC 9466). It should be noted that in a previous study, T2 was detrimental to hatchability. Inoculated eggs were transferred to 3 hatchers/T. At hatch, chicks were weighed, feather sexed, and hatch residue analysis was conducted. Male chicks were randomly assigned to 40 raised wire cage so that there were 10 birds/cage. On d 0, 7, 14, and 21 of the grow-out, chicks and feed were weighed to calculate performance data. On these days, the ileum and ceca were aseptically collected to enumerate total aerobes and coliforms. No differences were observed for percentage of mid dead embryos, cracked eggs, and cull chicks (P > 0.05). However, hatch of transfer was significantly reduced by T2 compared to T1, T3, and T4 (P < 0.001). T2 had significantly higher percentages of late dead embryos and pips when compared to the other treatments (P = 0.002 and P < 0.001, respectively). Chicks hatched from T2 were not vigorous and, thus, not used for the grow-out trial. No differences were observed for growth performance characteristics for any of the treatments (P > 0.05). For bacterial enumeration, the ileum had equal or fewer bacterial counts for T3 and T4 when compared to T1 on most sampling days, except on d21 where T4 had higher aerobic and coliform counts (P ≤ 0.0001). For the ceca, T3 and T4 had equal or fewer bacterial counts than T1 on every sampling day (P ≤ 0.0001). These data demonstrate that not all B. subtilis evaluated are detrimental to hatchability, but rather, serotype dependent. In addition, different B. subtilis serotypes can modify the intestinal microflora with potential to reduce pathogenic bacteria present in young broiler, without impacting overall performance.

Response of the ileum transcriptome to probiotic and fructo-oligosaccharides in Taiping chicken

Taiping chicken is indigenous chickens (Gallus gallus domesticus), which was one of China's excellent poultry species, is an excellent chicken in Gansu Province. As the problems caused by the overuse of antibiotics become more and more severe, people begin to look for ways to replace them. Among them, probiotics and fructo-oligosaccharides are the research hotspot to replace antibiotics. Probiotics and fructo-oligosaccharides can promote the absorption of nutrients, improve the ability to resist and prevent diseases, and improve the intestinal tissue morphology. In this study, we used RNA-Seq analysis to study the gene expression in ileum tissue after Taiping chicken was given probiotics and fructo-oligosaccharides. In total, 67 genes were differentially expressed in the ileum. Ten of the differently expressed genes were further validated by RT-qPCR. In addition, these differentially expressed genes were mainly enriched to tyrosine metabolism, AGE-RAGE signaling pathway in diabetic complications, phenylalanine metabolism, and pyrimidine metabolism. The results which this study provides contribute to our understanding application of probiotics and fructo-oligosaccharides in indigenous chickens production and provide a theoretical basis for the genetic development of indigenous chickens.

RNA-Seq transcriptome analysis of ileum in Taiping chicken supplemented with the dietary probiotic

Taiping chicken is indigenous chickens (Gallus gallus domesticus), which was one of China's excellent poultry species. As the problems caused by the overuse of antibiotics become more and more concern, people begin to look for ways to replace them. Among them, probiotics and their preparations are the research hotspot to replace antibiotics. Probiotics can promote the absorption of nutrients, improve the ratio of meat to meat, resist and prevent diseases, and improve the intestinal tissue morphology. Here, we performed transcriptome profiling of Taiping chicken ileum which was given probiotics by using the Hiseq™ 2500 sequencing platform. A total of 18 genes were differentially expressed in the ileum under control group and probiotics group. Thirteen genes were upregulated with a range of fold change from 1.02 to 8.61, and 5 were downregulated with a range of fold change from - 1.06 to - 2.29. Ten of the differently expressed genes were further validated by qRT-PCR. In addition, Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that these differentially expressed genes were mainly enriched to bile secretion, alpha-linolenic acid metabolism, linoleic acid metabolism, ether lipid metabolism, and arachidonic acid metabolism. This study will help us to understand the role of probiotics in indigenous chicken production and provide theoretical basis for the genetic development of indigenous chickens.

Impact of multi-strain probiotic, citric acid, garlic powder or their combinations on performance, ileal histomorphometry, microbial enumeration and humoral immunity of broiler chickens

Heat stress, one of the critical obstacles to poultry sector in subtropical and tropical countries, reduces performance, immune response, and animal welfare. This study examined the effect of dietary inclusion of probiotic (PRO), citric acid (CIT), garlic powder (GAR) or their combinations on growth, blood constituents, ileal microflora and morphology and humoral immunity of broiler chickens subjected to cyclic heat stress. Four hundred ninety one-day-old Ross-308 broiler chicks were randomly allocated to 7 groups with 7 replicates of 10 birds each as follows: control (C) group received the basal diet without supplements, PRO, CIT and GAR groups supplemented with 0.5 g kg^-1 multi-strain probiotic mixture (MPM), citric acid and garlic powder, respectively. PRO-CIT and PRO-GAR groups treated with 0.5 g kg^-1 MPM, and 0.5 g kg^-1 citric acid and garlic powder, while CIT-GAR group fed diet with 0.5 g kg^-1 of citric acid and garlic powder. Results revealed that dietary supplements and their combinations improved (P < 0.001) growth performance and decreased abdominal fat of heat-stressed birds. Dietary supplements decreased (P < 0.01) serum concentrations of cholesterol, triglycerides and LDL, while HDL was elevated (P < 0.05). Feed additives reduced (P < 0.01) ileal enumeration of Escherichia coli and total coliform while Lactobacillus count was increased (P < 0.05) only in MPM-enriched groups. Supplementation of these natural products improved (P < 0.01) ileal architecture while humoral immune response was not significantly influenced except antibody titre against Newcastle disease virus which was increased (P < 0.05) in MPM-supplemented groups. Conclusively, addition of the dietary supplements and their combinations, particularly, probiotic and citric acid combination can improve productive performance, and intestinal flora and histomorphometry of broilers exposed to cyclic heat stress.

In ovo inoculation of an Enterococcus faecium-based product to enhance broiler hatchability, live performance, and intestinal morphology

Previous studies have suggested the use of probiotics, as alternative to antibiotics, to enhance broiler performance. The administration of probiotics in feed has been widely explored; however, few studies have evaluated the in ovo inoculation of probiotics. Therefore, the objective was to evaluate the impact of in ovo inoculation of different concentrations of GalliPro Hatch (GH), an Enterococcus faecium-based probiotic, on hatchability, live performance, and gastrointestinal parameters. Ross x Ross 708 fertile eggs were incubated, and on day 18, injected with the following treatments: 1) 50 μL of Marek's vaccine (MV), 2) MV and 1.4 × 105 cfu GH/50 μL, 3) MV and 1.4 × 106 cfu GH/50 μL, 4) MV and 1.4 × 107 cfu GH/50 μL. On the day of hatch, chicks were weighed, feather sexed, and hatch residue was analyzed. Male birds (640) were randomly assigned to 40 floor pens. On day 0, 7, 14, and 21 of the grow-out phase, performance data were collected. One bird from each pen was used to obtain yolk weight and intestinal segment weight and length. Hatchability was not impacted by any GH treatment (P = 0.58). On day 0, yolk weight was lower for all treatments than for MV alone. On day 0 to 7, feed intake was lower for 105 and 107 GH; the feed conversion ratio (FCR) was lower for all treatments than for MV alone (P = 0.05; P = 0.01, respectively). From day 14 to 21, the 107 GH treatment had higher BW gain (P = 0.05). For day 0 to 21, 107 GH had a lower FCR than MV alone (P = 0.03). On day 0, all GH treatments resulted in heavier tissues and longer jejunum, ileum, and ceca lengths than MV alone (P < 0.05). Spleen weight was higher for 105 and 107 GH than for MV alone. In conclusion, GH does not impact hatchability, and some concentrations improved live performance through the first 21 d of the grow-out phase. These improvements could result from the increased yolk absorption and improved intestinal and spleen morphology seen in this study.

Live Bacterial Prophylactics in Modern Poultry

Commercial poultry farms frequently use live bacterial prophylactics like vaccines and probiotics to prevent bacterial infections. Due to the emergence of antibiotic-resistant bacteria in poultry animals, a closer examination into the health benefits and limitations of commercial, live prophylactics as an alternative to antibiotics is urgently needed. In this review, we summarize the peer-reviewed literature of several commercial live bacterial vaccines and probiotics. Per our estimation, there is a paucity of peer-reviewed published research regarding these products, making repeatability, product-comparison, and understanding biological mechanisms difficult. Furthermore, we briefly-outline significant issues such as probiotic-label accuracy, lack of commercially available live bacterial vaccines for major poultry-related bacteria such as Campylobacter and Clostridium perfringens, as well research gaps (i.e., probiotic-mediated vaccine adjuvancy, gut-brain-microbiota axis). Increased emphasis on these areas would open several avenues for research, ranging from improving protection against bacterial pathogens to using these prophylactics to modulate animal behavior.

Probiotics (Direct-Fed Microbials) in Poultry Nutrition and Their Effects on Nutrient Utilization, Growth and Laying Performance, and Gut Health: A Systematic Review

Simple Summary

Probiotics are live bacteria, fungi, or yeasts that supplement the gastrointestinal flora and help to maintain a healthy digestive system, thereby promoting the growth performance and overall health of poultry. Probiotics are increasingly being included in poultry diets as an alternative to antibiotics. This systematic review provides a summary of the use of probiotics in poultry production and the potential role of probiotics in the nutrient utilization, growth and laying performance, and gut health of poultry.

Abstract

Probiotics are live microorganisms which, when administered in adequate amounts, confer health benefits to the host. The use of probiotics in poultry has increased steadily over the years due to higher demand for antibiotic-free poultry. The objective of this systematic review is to present and evaluate the effects of probiotics on the nutrient utilization, growth and laying performance, gut histomorphology, immunity, and gut microbiota of poultry. An electronic search was conducted using relevant keywords to include papers pertinent to the topic. Seventeen commonly used probiotic species were critically assessed for their roles in the performance and gut health of poultry under existing commercial production conditions. The results showed that probiotic supplementation could have the following effects: (1) modification of the intestinal microbiota, (2) stimulation of the immune system, (3) reduction in inflammatory reactions, (4) prevention of pathogen colonization, (5) enhancement of growth performance, (6) alteration of the ileal digestibility and total tract apparent digestibility coefficient, and (7) decrease in ammonia and urea excretion. Thus, probiotics can serve as a potential alternative to antibiotic growth promoters in poultry production. However, factors such as the intestinal health condition of birds, the probiotic inclusion level; and the incubation conditions, feedstuff, and water quality offered to birds may affect the outcome. This systematic review provides a summary of the use of probiotics in poultry production, as well as the potential role of probiotics in the nutrient utilization, growth and laying performance, and gut health of poultry.

Cecal microbiome composition and metabolic function in probiotic treated broilers

Probiotics have become increasingly popular in the poultry industry as a promising nutritional intervention to promote the modulation of intestinal microbial communities and their metabolic activities as a means of improving health and performance. This study aimed to determine the influence of different probiotic formulations on the taxonomic and metabolic profiling of cecal microbial communities, as well as to define associations between cecal microbiota and growth parameters in 21 and 42-day-old broilers. Probiotics investigated included a synbiotic (SYNBIO), a yeast-based probiotic (YEAST), and three single-strain formulations of spore-forming Bacillus amyloliquefaciens (SINGLE1), B. subtilis (SINGLE2) and B. licheniformis (SINGLE3). Dietary inclusion of SYNBIO, YEAST, SINGLE2, and SINGLE3 into the diets supported a significant stimulation of BW and BWG by 7 days of age. Besides, SYNBIO reduced the overall mortality rate by 42d (p<0.05). No significant variation was observed among different probiotic-based formulations for cecal microbiota composition. However, there was a treatment-specific effect on the metabolic profiles, with a particular beneficial metabolic adaptation by the microbiota when supplemented by SYNBIO and SINGLE2. Furthermore, the population of Lactobacillales was identified to be strongly associated with lower Enterobacteriales colonization, higher BW means, and lower mortality rate of growing broilers. Overall, the results emphasize that probiotic supplementation may enhance the microbial energy metabolism in the ceca of young broilers.

Post hatch recovery of a probiotic Enterococcus faecium strain in the yolk sac and intestinal tract of broiler chickens after in ovo injection

Concerns about antibiotic-resistant bacteria and their presence in animal products grow and thus alternatives to use of antibiotics in animal production are being investigated. Probiotics have gained increased focus due to improvements in performance, immune health and pathogen reduction when provided to poultry through feed. These traits may be further improved if probiotics can be provided to the embryo before hatch, before meeting environmental pathogens. The objective was to determine the faith of a probiotic Enterococcus faecium (M74) strain in the yolk sac and intestinal tract of broiler chickens after injection into hatching eggs. E. faecium M74 (1.4 × 107 CFU/egg) was applied in ovo at day 18 of incubation. From 1- and 7-day-old chickens, 20 samples from yolk sac, caecal tonsils and rest of the intestinal tract were subjected to CFU counting. Isolates from a sample subset were typed by pulsed-field gel electrophoresis (PFGE). Enterococci were found in varying numbers: 1.0 × 104-2.2 × 1010 CFU/g. The prevalence of M74 PFGE profiles was high in 1-day-old (88%) and 7-day-old chickens (67%). This demonstrates that the embryos ingested M74 before hatching, that M74 is viable for intestinal colonization through in ovo administration, and that the strain multiplies in the chickens gastrointestinal tract post hatching.

The potential for inoculating Lactobacillus animalis and Enterococcus faecium alone or in combination using commercial in ovo technology without negatively impacting hatch and post-hatch performance

The poultry industry has recently undergone transitions into antibiotic free production, and viable antibiotic alternatives, such as probiotics, are necessary. Through in ovo probiotic inoculation, beneficial microflora development in the gastrointestinal tract may occur prior to hatch without negatively impacting chick performance. Therefore, the objective of the present study was to observe the impacts of the injection of probiotic bacteria individually or combined into fertile broiler hatching eggs on hatch and live performance characteristics. A total of 2,080 fertile broiler hatching eggs were obtained from a commercial source. On day 18 of incubation, 4 in ovo injected treatments were applied: 1.) Marek's Disease (HVT) vaccination, 2.) L. animalis (∼10⁶ cfu/50μl), 3.) E. faecium (∼10⁶ cfu/50μl), and 4.) L. animalis + E. faecium (∼10⁶ cfu & ∼10⁶ cfu/50μl each). On day of hatch, hatchability and hatch residue data were recorded. A portion of male chicks from each treatment were placed in a grow-out facility for a 21 d grow-out (18 chicks/pen × 10 pens/treatment = 720 male chicks) with a corn and soy bean meal-based diet without antibiotics or antibiotic alternatives. Performance data and gastrointestinal samples were collected on days 0, 7, 14, and 21. Results indicated no differences in all hatch parameters between treatments (P > 0.05) except for % pipped, where the L. animalis treatment had lower % pipped eggs compared to the HVT control and E. faecium treatments (P = 0.04). No differences were observed in body weight gain or mortality (P > 0.05). Probiotic treatments altered gastrointestinal tissue length, weight, and pH. This resulted in all in ovo injected probiotic treatments increasing feed conversion ratio (FCR) from days 7 to 14 as compared to the control (P = 0.01). Differences in FCR were not observed in any other week of data collection (days 0 to 7, 14 to 21, or 0 to 21; P > 0.05). Although probiotics altered live performance from days 7 to 14, these data suggest that in ovo inoculations of L. animalis and E. faecium in combination are viable probiotic administration practices that potentially improve hatch characteristics and gastrointestinal tract development.

In ovo injection of nano-selenium spheres mitigates the hatchability, histopathology image and immune response of hatched chicks

In ovo injection of nano-selenium (Se) produced by lactic acid bacteria (LAB-nano-Se) was investigated on the hatchability, immune responses and the histopathological alterations in hatched chicks. The eggs (18 day age) were injected with 0.5 ml of 0.9% NaCl (normal saline, NS), while the control group was kept without injection. In the third, fourth and fifth groups, the eggs were injected with 0.5 ml of NS and LAB-nano-Se at 10, 20 and 30 μg/egg. The results revealed improved growth performance in groups injected with LAB-nano-Se when compared to the control treatment. The highest final weight and weight gain were noticed in 20 μg LAB-nano-Se/egg group (p < .05). The feed conversion ratio was reduced in all treated groups when compared to the control group (p < .05). Groups injected with LAB-nano-Se showed enhanced hatchability of the whole incubated eggs (p < .05). Total lipids and cholesterol levels were decreased significantly in groups treated with LAB-nano-Se at 10 and 20 μg/egg when compared to the non-treated group. At the same time, globulin was increased by LAB-nano-Se in ovo injection. Furthermore, the total antioxidant capacity, catalase, glutathione peroxidase, superoxide dismutase increased in groups treated with LAB-nano-Se at 10 and 20 μg/egg with insignificant (p > .05) differences with those treated with LAB-nano-Se at 30 μg/egg using in ovo injection technique. Also, higher total blood protein and phagocytosis were significantly observed in groups treated with at 10, 20 and 30 μg LAB-nano-Se/egg. The histopathological images of hatched chicks revealed that nano-Se presented normal effects on liver and kidney tissues and restored the parameters as mentioned earlier. To conclude, LAB-nano-Se exhibited beneficial effects in hatched chicks through improving immune and antioxidant activities as well as histopathological effects by using in ovo technique.