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Animal Production Science Animal Production Science Society
Food, fibre and pharmaceuticals from animals
REVIEW (Open Access)

Probiotics and gut health: linking gut homeostasis and poultry productivity

S. Shini https://orcid.org/0000-0003-2654-4826 A B and W. L. Bryden https://orcid.org/0000-0002-7187-4464 A
+ Author Affiliations
- Author Affiliations

A School of Agriculture and Food Sciences, University of Queensland, Gatton, Qld 4343, Australia.

B Corresponding author. Email: s.shini@uq.edu.au

Animal Production Science 62(12) 1090-1112 https://doi.org/10.1071/AN20701
Submitted: 30 December 2020  Accepted: 05 April 2021   Published: 17 June 2021

Journal compilation © CSIRO 2022 Open Access CC BY-NC-ND

Abstract

The use of probiotics in poultry production has increased rapidly, and this movement has been promoted by global events, such as the prohibition or decline in the use of antibiotic growth promotants in poultry feeds. There has been a persistent search for alternative feed additives, and probiotics have shown that they can restore the composition of the gut microbiota, and produce health benefits to the host, including improvements in performance. Probiotics have shown potential to increase productivity in poultry, especially in flocks challenged by stressors. However, the outcomes of probiotic use have not always been consistent. There is an increasing demand for well defined products that can be applied strategically, and currently, probiotic research is focusing on delineating their mechanisms of action in the gut that contribute to an improved efficacy. In particular, mechanisms involved in the maintenance and protection of intestinal barrier integrity and the role of the gut microbiota are being extensively investigated. It has been shown that probiotics modulate intestinal immune pathways both directly and through interactions with the gut microbiota. These interactions are key to maintaining gut homeostasis and function, and improving feed efficiency. Research has demonstrated that probiotics execute their effects through multiple mechanisms. The present review describes recent advances in probiotic use in poultry. It focuses on the current understanding of gut homeostasis and gut health in chickens, and how it can be assessed and improved through supplementation of poultry diets with probiotics in poultry diets. In particular, cellular and molecular mechanisms involved in the maintenance and protection of gut barrier structure and function are described. It also highlights important factors that influence probiotic efficacy and bird performance.

Keywords: microbiota, mode of action, mucosal integrity, intestinal health, immunomodulation, necrotic enteritis, broiler performance.


References

Aalaei M, Khatibjoo A, Zaghari M, Taherpou K, Akbari-Gharaei M, Soltani M (2019) Effect of single- and multi-strain probiotics on broiler breeder performance, immunity and intestinal toll-like receptors expression. Journal of Applied Animal Research 47, 236–242.
Effect of single- and multi-strain probiotics on broiler breeder performance, immunity and intestinal toll-like receptors expression.Crossref | GoogleScholarGoogle Scholar |

Abdulkhaleq LA, Assi MA, Abdullah R, Zamri-Saad M, Taufiq-Yap YH, Hezmee MNM (2018) The crucial roles of inflammatory mediators in inflammation: a review. Veterinary World 11, 627–635.
The crucial roles of inflammatory mediators in inflammation: a review.Crossref | GoogleScholarGoogle Scholar | 29915501PubMed |

Abudabos A, Alyemni A, Zakaria HAH (2016) Effect of two strains of probiotics on the antioxidant capacity, oxidative stress, and immune responses of Salmonella-challenged broilers. Brazilian Journal of Poultry Science 18, 175–180.
Effect of two strains of probiotics on the antioxidant capacity, oxidative stress, and immune responses of Salmonella-challenged broilers.Crossref | GoogleScholarGoogle Scholar |

Adeola O, Cowieson AJ (2011) Board-invited review: opportunities and challenges in using exogenous enzymes to improve nonruminant animal production. Journal of Animal Science 89, 3189–3218.
Board-invited review: opportunities and challenges in using exogenous enzymes to improve nonruminant animal production.Crossref | GoogleScholarGoogle Scholar | 21512114PubMed |

Ahaduzzaman Md, Keerqin C, Kumar A, Musigwa S, Morgan N, Kheravii SK, Sharpe S, Williamson S, Wu S-B, Walkden-Brown SW, Gerber PF (2021) Detection and quantification of Clostridium perfringens and Eimeria spp. in poultry dust using real-time PCR under experimental and field conditions. Avian Diseases 65, 77–85.

Al-Sheikhly F, Al-Saieg A (1980) Role of coccidia in the occurrence of necrotic enteritis of chickens. Avian Diseases 24, 324–333.
Role of coccidia in the occurrence of necrotic enteritis of chickens.Crossref | GoogleScholarGoogle Scholar | 6254485PubMed |

Algburi A, Alazzawi SA, Al-Ezzy AIA, Weeks R, Chistyakov V, Chikindas ML (2020) Potential probiotics Bacillus subtilis KATMIRA1933 and Bacillus amyloliquefaciens B-1895 co-aggregate with clinical isolates of Proteus mirabilis and prevent biofilm formation. Probiotics and Antimicrobial Proteins 12, 1471–1483.
Potential probiotics Bacillus subtilis KATMIRA1933 and Bacillus amyloliquefaciens B-1895 co-aggregate with clinical isolates of Proteus mirabilis and prevent biofilm formation.Crossref | GoogleScholarGoogle Scholar | 31989448PubMed |

Allaire JM, Crowley SM, Law HT, Chang SY, Ko HJ, Vallance BA (2018) The intestinal epithelium: central coordinator of mucosal immunity. Trends in Immunology 39, 677–696.
The intestinal epithelium: central coordinator of mucosal immunity.Crossref | GoogleScholarGoogle Scholar | 29716793PubMed |

Aluwong T, Kawu M, Raji M, Dzenda T, Govwang F, Sinkalu V, Ayo J (2013) Effect of yeast probiotic on growth, antioxidant enzyme activities and malondialdehyde concentration of broiler chickens. Antioxidants 2, 326–339.
Effect of yeast probiotic on growth, antioxidant enzyme activities and malondialdehyde concentration of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 26784468PubMed |

Angelakis E (2017) Weight gain by gut microbiota manipulation in productive animals. Microbial Pathogenesis 106, 162–170.
Weight gain by gut microbiota manipulation in productive animals.Crossref | GoogleScholarGoogle Scholar | 27836763PubMed |

Annett CB, Viste JR, Chirino-Trejo M, Classen HL, Middleton DM, Simko E (2002) Necrotic enteritis: effect of barley, wheat and corn diets on proliferation of Clostridium perfringens type A. Avian Pathology 31, 598–601.
Necrotic enteritis: effect of barley, wheat and corn diets on proliferation of Clostridium perfringens type A.Crossref | GoogleScholarGoogle Scholar | 12593744PubMed |

Annison EF, Hill KJ, Kenworthy R (1968) Volatile fatty acids in the digestive tract of the fowl. British Poultry Science 22, 207–216.

Antonissen G, Eeckhaut V, Van Driessche K, Onrust L, Haesebrouck F, Ducatelle R, Moore RJ, Van Immerseel F (2016) Microbial shifts associated with necrotic enteritis. Avian Pathology 45, 308–312.
Microbial shifts associated with necrotic enteritis.Crossref | GoogleScholarGoogle Scholar | 26950294PubMed |

Applegate TJ, Klose V, Steiner T, Ganner A, Schatzmayr G (2010) Probiotics and phytogenics for poultry: myth or reality. Journal of Applied Poultry Research 19, 194–210.
Probiotics and phytogenics for poultry: myth or reality.Crossref | GoogleScholarGoogle Scholar |

Araujo R, Polycarpo G, Barbieri A, Silva K, Ventura G, Polycarpo V (2019) Performance and economic viability of broiler chickens fed with probiotic and organic acids in an attempt to replace growth-promoting antibiotics. Brazilian Journal of Poultry Science 21, eRBCA-2018–0912

Bai K, Huang Q, Zhang J, He J, Zhang L, Wang T (2017) Supplemental effects of probiotic Bacillus subtilis fmbJ on growth performance, antioxidant capacity, and meat quality of broiler chickens. Poultry Science 96, 74–82.
Supplemental effects of probiotic Bacillus subtilis fmbJ on growth performance, antioxidant capacity, and meat quality of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 27486257PubMed |

Bajagai YS, Klieve AV, Dart PJ, Bryden WL (2016) ‘Probiotics in animal nutrition: production, impact and regulation. FAO Animal Production and Health paper no. 179.’ (Ed. HPS Makkar) (FAO: Rome, Italy)

Baquero F, Nombela C (2012) The microbiome as a human organ. Clinical Microbiology and Infection 18, 2–4.
The microbiome as a human organ.Crossref | GoogleScholarGoogle Scholar | 22647038PubMed |

Barekatain R, Howarth GS, Willson N-L, Cadogan D, Wilkinson S (2020) Excreta biomarkers in response to different gut barrier dysfunction models and probiotic supplementation in broiler chickens. PLoS One 15, e0237505
Excreta biomarkers in response to different gut barrier dysfunction models and probiotic supplementation in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 32790727PubMed |

Baxter MFA, Latorre JD, Dridi S, Merino-Guzman R, Hernandez-Velasco X, Hargis BM, Tellez-Isaias G (2019) Identification of serum biomarkers for intestinal integrity in a broiler chicken malabsorption model. Frontiers in Veterinary Science 6, 144
Identification of serum biomarkers for intestinal integrity in a broiler chicken malabsorption model.Crossref | GoogleScholarGoogle Scholar | 31143767PubMed |

Bederska-Łojewska D, Świątkiewicz S, Arczewska-Włosek A, Schwarz T (2017) Rye non-starch polysaccharides: their impact on poultry intestinal physiology, nutrients digestibility and performance indices – a review. Annals of Animal Science 17, 351–369.
Rye non-starch polysaccharides: their impact on poultry intestinal physiology, nutrients digestibility and performance indices – a review.Crossref | GoogleScholarGoogle Scholar |

Bedford MR (2000) Exogenous enzymes in monogastric nutrition: their current value and future benefits. Animal Feed Science and Technology 86, 1–13.
Exogenous enzymes in monogastric nutrition: their current value and future benefits.Crossref | GoogleScholarGoogle Scholar |

Bedford MR (2018) The evolution and application of enzymes in the animal feed industry: the role of data interpretation. British Poultry Science 59, 486–493.

Bermudez-Brito M, Plaza-Díaz J, Muñoz-Quezada S, Gómez-Llorente C, Gil A (2012) Probiotic mechanisms of action. Annals of Nutrition & Metabolism 61, 160–174.
Probiotic mechanisms of action.Crossref | GoogleScholarGoogle Scholar |

Booijink CC, El-Aidy S, Rajilic-Stojanovic M, Heilig HG, Troost FJ, Smidt H, Kleerebezem M, De Vos WM, Zoetendal EG (2010) High temporal and inter-individual variation detected in the human ileal microbiota. Environmental Microbiology 12, 3213–3227.
High temporal and inter-individual variation detected in the human ileal microbiota.Crossref | GoogleScholarGoogle Scholar | 20626454PubMed |

Borda-Molina D, Seifert J, Camarinha-Silva A (2018) Current perspectives of the chicken gastrointestinal tract and its microbiome. Computational and Structural Biotechnology Journal 16, 131–139.
Current perspectives of the chicken gastrointestinal tract and its microbiome.Crossref | GoogleScholarGoogle Scholar | 30026889PubMed |

Broom LJ (2019) Host-microbe interactions and gut health in poultry: focus on innate responses. Microorganisms 7, 139
Host-microbe interactions and gut health in poultry: focus on innate responses.Crossref | GoogleScholarGoogle Scholar |

Bryden WL, Li X, Ruhnke I, Zhang D, Shini S (2021) Nutrition, feeding and laying hen welfare. Animal Production Science 61, 893–914.
Nutrition, feeding and laying hen welfare.Crossref | GoogleScholarGoogle Scholar |

Cameron C, McAllister TA (2019) Could probiotics be the panacea alternative to the use of antimicrobials in livestock diets? Beneficial Microbes 10, 773–799.
Could probiotics be the panacea alternative to the use of antimicrobials in livestock diets?Crossref | GoogleScholarGoogle Scholar |

Camilleri M (2019) Leaky gut: mechanisms, measurement and clinical implications in humans. Gut 68, 1516–1526.
Leaky gut: mechanisms, measurement and clinical implications in humans.Crossref | GoogleScholarGoogle Scholar | 31076401PubMed |

Cao GT, Zeng XF, Chen AG, Zhou L, Zhang L, Xiao YP, Yang CM (2013) Effects of a probiotic, Enterococcus faecium, on growth performance, intestinal morphology, immune response, and cecal microflora in broiler chickens challenged with Escherichia coli K88. Poultry Science 92, 2949–2955.
Effects of a probiotic, Enterococcus faecium, on growth performance, intestinal morphology, immune response, and cecal microflora in broiler chickens challenged with Escherichia coli K88.Crossref | GoogleScholarGoogle Scholar | 24135599PubMed |

Cao L, Wu XH, Bai YL, Wu XY, Gu SB (2019) Anti-inflammatory and antioxidant activities of probiotic powder containing Lactobacillus plantarum 1.2567 in necrotic enteritis model of broiler chickens. Livestock Science 223, 157–163.
Anti-inflammatory and antioxidant activities of probiotic powder containing Lactobacillus plantarum 1.2567 in necrotic enteritis model of broiler chickens.Crossref | GoogleScholarGoogle Scholar |

Celi P, Verlhac V, Pérez Calvo E, Schmeisser J, Kluenter A-M (2019) Biomarkers of gastrointestinal functionality in animal nutrition and health. Animal Feed Science and Technology 250, 9–31.
Biomarkers of gastrointestinal functionality in animal nutrition and health.Crossref | GoogleScholarGoogle Scholar |

Cengiz Ö, Köksal BH, Tatlı O, Sevim Ö, Ahsan U, Üner AG, Ulutaş PA, Beyaz D, Büyükyörük S, Yakan A, Önol AG (2015) Effect of dietary probiotic and high stocking density on the performance, carcass yield, gut microflora, and stress indicators of broilers. Poultry Science 94, 2395–2403.
Effect of dietary probiotic and high stocking density on the performance, carcass yield, gut microflora, and stress indicators of broilers.Crossref | GoogleScholarGoogle Scholar | 26240393PubMed |

Charlebois A, Jacques M, Archambault M (2014) Biofilm formation of Clostridium perfringens and its exposure to low-dose antimicrobials. Frontiers in Microbiology 5, 183
Biofilm formation of Clostridium perfringens and its exposure to low-dose antimicrobials.Crossref | GoogleScholarGoogle Scholar | 24795711PubMed |

Chase DG, Erlandsen SL (1976) Evidence for a complex life cycle and endospore formation in the attached, filamentous, segmented bacterium from murine ileum. Journal of Bacteriology 127, 572–583.
Evidence for a complex life cycle and endospore formation in the attached, filamentous, segmented bacterium from murine ileum.Crossref | GoogleScholarGoogle Scholar | 931952PubMed |

Chen J, Tellez G, Richards JD, Escobar J (2015) Identification of potential biomarkers for gut barrier failure in broiler chickens. Frontiers in Veterinary Science 2, 1–10.
Identification of potential biomarkers for gut barrier failure in broiler chickens.Crossref | GoogleScholarGoogle Scholar |

Chichlowski M, Croom J, McBride BW, Daniel L, Davis G, Koci MD (2007) Direct-fed microbial primalac and salinomycin modulate whole-body and intestinal oxygen consumption and intestinal mucosal cytokine production in the broiler chick. Poultry Science 86, 1100–1106.
Direct-fed microbial primalac and salinomycin modulate whole-body and intestinal oxygen consumption and intestinal mucosal cytokine production in the broiler chick.Crossref | GoogleScholarGoogle Scholar | 17495079PubMed |

Choct M (2009) Managing gut health through nutrition. British Poultry Science 50, 9–15.
Managing gut health through nutrition.Crossref | GoogleScholarGoogle Scholar | 19234925PubMed |

Coates ME (1986) The biologist’s debt to the domestic fowl. British Poultry Science 27, 3–10.
The biologist’s debt to the domestic fowl.Crossref | GoogleScholarGoogle Scholar | 3708405PubMed |

Collado MC, Gueimonde M, Hernández M, Sanz Y, Salminen S (2005) Adhesion of selected Bifidobacterium strains to human intestinal mucus and the role of adhesion in enteropathogen exclusion. Journal of Food Protection 68, 2672–2678.
Adhesion of selected Bifidobacterium strains to human intestinal mucus and the role of adhesion in enteropathogen exclusion.Crossref | GoogleScholarGoogle Scholar | 16355841PubMed |

Collier CT, Hofacre CL, Payne AM, Anderson DB, Kaiser P, Mackie RI, Gaskins HR (2008) Coccidia-induced mucogenesis promotes the onset of necrotic enteritis by supporting Clostridium perfringens growth. Veterinary Immunology and Immunopathology 122, 104–115.
Coccidia-induced mucogenesis promotes the onset of necrotic enteritis by supporting Clostridium perfringens growth.Crossref | GoogleScholarGoogle Scholar | 18068809PubMed |

Cutting SM (2011) Bacillus probiotics. Food Microbiology 28, 214–220.
Bacillus probiotics.Crossref | GoogleScholarGoogle Scholar | 21315976PubMed |

Dänicke S, Moors E, Beineke A, Gauly M (2009) Ascaridia galli infection of pullets and intestinal viscosity: consequences for nutrient retention and gut morphology. British Poultry Science 50, 512–520.
Ascaridia galli infection of pullets and intestinal viscosity: consequences for nutrient retention and gut morphology.Crossref | GoogleScholarGoogle Scholar | 19735021PubMed |

De Cesare A, Sirri F, Manfreda G, Moniaci P, Giardini A, Zampiga M, Meluzzi A (2017) Effect of dietary supplementation with Lactobacillus acidophilus D2/CSL (CECT 4529) on caecum microbioma and productive performance in broiler chickens. PLoS One 12, e0176309
Effect of dietary supplementation with Lactobacillus acidophilus D2/CSL (CECT 4529) on caecum microbioma and productive performance in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 28472118PubMed |

De Meyer F, Eeckhaut V, Ducatelle R, Dhaenens M, Daled S, Dedeurwaerder A, De Gussem M, Haesebrouck F, Deforce D, Van Immerseel F (2019) Host intestinal biomarker identification in a gut leakage model in broilers. Veterinary Research 50, 46
Host intestinal biomarker identification in a gut leakage model in broilers.Crossref | GoogleScholarGoogle Scholar | 31215487PubMed |

de Santa Barbara P, van den Brink GR, Roberts DJ (2003) Development and differentiation of the intestinal epithelium. Cellular and Molecular Life Sciences: CMLS 60, 1322–1332.
Development and differentiation of the intestinal epithelium.Crossref | GoogleScholarGoogle Scholar | 12943221PubMed |

de Simone C (2019) The unregulated probiotic market. Clinical Gastroenterology and Hepatology 17, 809–817.
The unregulated probiotic market.Crossref | GoogleScholarGoogle Scholar | 29378309PubMed |

de Souza LFA, Araújo DN, Stefani LM, Giometti IC, Cruz-Polycarpo VC, Polycarpo G, Burbarelli MF (2018) Probiotics on performance, intestinal morphology and carcass characteristics of broiler chickens raised with lower or higher environmental challenge. Austral Journal of Veterinary Sciences 50, 35–41.
Probiotics on performance, intestinal morphology and carcass characteristics of broiler chickens raised with lower or higher environmental challenge.Crossref | GoogleScholarGoogle Scholar |

Denbow DM (2015) Gastrointestinal anatomy and physiology. In ‘Sturkie’s Avian Physiology’. 6th edn. (Ed. CG Scanes) pp. 337–366. (Elsevier Inc.: New York, NY, USA)

Diaz Carrasco JM, Casanova NA, Fernández Miyakawa ME (2019) Microbiota, gut health and chicken productivity: what is the connection? Microorganisms 7, 374–389.
Microbiota, gut health and chicken productivity: what is the connection?Crossref | GoogleScholarGoogle Scholar |

Ding J, Dai R, Yang L, He C, Xu K, Liu S, Zhao W, Xiao L, Luo L, Zhang Y, Meng H (2017) Inheritance and establishment of gut microbiota in chickens. Frontiers in Microbiology 8, 1967
Inheritance and establishment of gut microbiota in chickens.Crossref | GoogleScholarGoogle Scholar | 29067020PubMed |

Drew MD, Syed NA, Goldade BG, Laarveld B, Van Kessel AG (2004) Effects of dietary protein source and level on intestinal populations of Clostridium perfringens in broiler chickens. Poultry Science 83, 414–420.
Effects of dietary protein source and level on intestinal populations of Clostridium perfringens in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 15049494PubMed |

Ducatelle R, Goossens E, De Meyer F, Eeckhaut V, Antonissen G, Haesebrouck F, Van Immerseel F (2018) Biomarkers for monitoring intestinal health in poultry: present status and future perspectives. Veterinary Research 49, 43
Biomarkers for monitoring intestinal health in poultry: present status and future perspectives.Crossref | GoogleScholarGoogle Scholar | 29739469PubMed |

Dunlop MW, Moss AF, Groves PJ, Wilkinson SJ, Stuetz RM, Selle PH (2016) The multidimensional causal factors of ‘wet litter’ in chicken-meat production. The Science of the Total Environment 562, 766–776.
The multidimensional causal factors of ‘wet litter’ in chicken-meat production.Crossref | GoogleScholarGoogle Scholar | 27110988PubMed |

Eckert NH, Lee JT, Hyatt D, Stevens SM, Anderson S, Anderson PN, Beltran R, Schatzmayr G, Mohnl M, Caldwell DJ (2010) Influence of probiotic administration by feed or water on growth parameters of broilers reared on medicated and nonmedicated diets. Journal of Applied Poultry Research 19, 59–67.
Influence of probiotic administration by feed or water on growth parameters of broilers reared on medicated and nonmedicated diets.Crossref | GoogleScholarGoogle Scholar |

Edens F (2003) An alternative for antibiotic use in poultry: probiotics. Brazilian Journal of Poultry Science 5, 75–97.
An alternative for antibiotic use in poultry: probiotics.Crossref | GoogleScholarGoogle Scholar |

Elshaghabee FMF, Rokana N, Gulhane RD, Sharma C, Panwar H (2017) Bacillus as potential probiotics: status, concerns, and future perspectives. Frontiers in Microbiology 8, 1490
Bacillus as potential probiotics: status, concerns, and future perspectives.Crossref | GoogleScholarGoogle Scholar | 28848511PubMed |

Elwinger K, Schneitz C, Berndtson E, Fossum O, Teglöf B, Engstöm B (1992) Factors affecting the incidence of necrotic enteritis, caecal carriage of Clostridium perfringens and bird performance in broiler chicks. Acta Veterinaria Scandinavica 33, 369–378.
Factors affecting the incidence of necrotic enteritis, caecal carriage of Clostridium perfringens and bird performance in broiler chicks.Crossref | GoogleScholarGoogle Scholar | 1488953PubMed |

Elwinger K, Berndtson E, Engström B, Fossum O, Waldenstedt L (1998) Effect of antibiotic growth promoters and anticoccidials on growth of Clostridium perfringens in the caeca and on performance of broiler chickens. Acta Veterinaria Scandinavica 39, 433–441.
Effect of antibiotic growth promoters and anticoccidials on growth of Clostridium perfringens in the caeca and on performance of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 9926457PubMed |

Ericsson AC, Hagan CE, Davis DJ, Franklin CL (2014) Segmented filamentous bacteria: commensal microbes with potential effects on research. Comparative Medicine 64, 90–98.

Even M, Davail S, Rey M, Tavernier A, Houssier M, Bernadet MD, Gontier K, Pascal G, Ricaud K (2018) Probiotics strains modulate gut microbiota and lipid metabolism in mule ducks. The Open Microbiology Journal 12, 71–93.
Probiotics strains modulate gut microbiota and lipid metabolism in mule ducks.Crossref | GoogleScholarGoogle Scholar | 29755604PubMed |

FAO/WHO (2006) Probiotics in food: health and nutritional properties and guidelines for evaluation. A report of a Joint FAO/WHO Expert Consultation on Evaluation of Health and Nutritional Properties of Probiotics in Food including Powder Milk with Live lactic acid bacteria, Cordoba, Argentina, 1–4 October 2001, Rome, Italy. Available at http://www.fao.org/3/a-a0512e.pdf [Verified 2 November 2020]

FDA (2017) Fact sheet. Veterinary feed directive final rule and next steps. Available at https://www.fda.gov/animal-veterinary/development-approval-process/fact-sheet-veterinary-feed-directive-final-rule-and-next-steps [Verified October 2020]

Flannigan KL, Denning TL (2018) Segmented filamentous bacteria-induced immune responses: a balancing act between host protection and autoimmunity. Immunology 154, 537–546.
Segmented filamentous bacteria-induced immune responses: a balancing act between host protection and autoimmunity.Crossref | GoogleScholarGoogle Scholar |

Forssten S, Ouwehand CA (2020) Dose–response recovery of probiotic strains in simulated gastro-intestinal passage. Microorganisms 8, 112
Dose–response recovery of probiotic strains in simulated gastro-intestinal passage.Crossref | GoogleScholarGoogle Scholar |

Forte C, Acuti G, Manuali E, Casagrande Proietti P, Pavone S, Trabalza-Marinucci M, Moscati L, Onofri A, Lorenzetti C, Franciosini MP (2016) Effects of two different probiotics on microflora, morphology, and morphometry of gut in organic laying hens. Poultry Science 95, 2528–2535.
Effects of two different probiotics on microflora, morphology, and morphometry of gut in organic laying hens.Crossref | GoogleScholarGoogle Scholar | 27143778PubMed |

Furness JB, Cottrell JJ (2017) Signalling from the gut lumen. Animal Production Science 57, 2175–2187.
Signalling from the gut lumen.Crossref | GoogleScholarGoogle Scholar |

Gadde U, Kim WH, Oh ST, Lillehoj HS (2017) Alternatives to antibiotics for maximizing growth performance and feed efficiency in poultry: a review. Animal Health Research Reviews 18, 26–45.
Alternatives to antibiotics for maximizing growth performance and feed efficiency in poultry: a review.Crossref | GoogleScholarGoogle Scholar | 28485263PubMed |

Gagliardi A, Totino V, Cacciotti F, Iebba V, Neroni B, Bonfiglio G, Trancassini M, Passariello C, Pantanella F, Schippa S (2018) Rebuilding the gut microbiota ecosystem. International Journal of Environmental Research and Public Health 15, 1679
Rebuilding the gut microbiota ecosystem.Crossref | GoogleScholarGoogle Scholar |

Garner CE, Smith S, Elviss NC, Humphrey TJ, White P, Ratcliffe NM, Probert CS (2008) Identification of Campylobacter infection in chickens from volatile faecal emissions. Biomarkers 13, 413–421.
Identification of Campylobacter infection in chickens from volatile faecal emissions.Crossref | GoogleScholarGoogle Scholar | 18484355PubMed |

Gerritsen J, Smidt H, Rijkers GT, de Vos WM (2011) Intestinal microbiota in human health and disease: the impact of probiotics. Genes & Nutrition 6, 209–240.
Intestinal microbiota in human health and disease: the impact of probiotics.Crossref | GoogleScholarGoogle Scholar |

Gholamiandehkordi AR, Timbermont L, Lanckriet A, Van Den Broeck W, Pedersen K, Dewulf J, Pasmans F, Haesebrouck F, Ducatelle R, Van Immerseel F (2007) Quantification of gut lesions in a subclinical necrotic enteritis model. Avian Pathology 36, 375–382.
Quantification of gut lesions in a subclinical necrotic enteritis model.Crossref | GoogleScholarGoogle Scholar | 17899461PubMed |

Gomide MH, Sterzo EV, Macari M, Boleli IC (2004) Use of scanning electron microscopy for the evaluation of intestinal epithelium integrity. Brasilian Journal of Animal Science 33, 1500–1505.

Goodwin MA, Cooper GL, Brown J, Bickford AA, Waltman WD, Dickson TG (1991) Clinical, pathological, and epizootiological features of long-segmented filamentous organisms (bacteria, LSFOs) in the small intestines of chickens, turkeys, and quails. Avian Diseases 35, 872–876.
Clinical, pathological, and epizootiological features of long-segmented filamentous organisms (bacteria, LSFOs) in the small intestines of chickens, turkeys, and quails.Crossref | GoogleScholarGoogle Scholar | 1786018PubMed |

Goossens E, Debyser G, Callens C, De Gussem M, Dedeurwaerder A, Devreese B, Haesebrouck F, Flügel M, Pelzer S, Thiemann F, Ducatelle R, Van Immerseel F (2018) Elevated faecal ovotransferrin concentrations are indicative for intestinal barrier failure in broiler chickens. Veterinary Research 49, 51
Elevated faecal ovotransferrin concentrations are indicative for intestinal barrier failure in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 29925427PubMed |

Haberecht S, Bajagai YS, Moore RJ, Van TTH, Stanley D (2020) Poultry feeds carry diverse microbial communities that influence chicken intestinal microbiota colonisation and maturation. AMB Express 10, 143
Poultry feeds carry diverse microbial communities that influence chicken intestinal microbiota colonisation and maturation.Crossref | GoogleScholarGoogle Scholar | 32803529PubMed |

Haghighi HR, Abdul-Careem MF, Dara RA, Chambers JR, Sharif S (2008) Cytokine gene expression in chicken cecal tonsils following treatment with probiotics and Salmonella infection. Veterinary Microbiology 126, 225–233.
Cytokine gene expression in chicken cecal tonsils following treatment with probiotics and Salmonella infection.Crossref | GoogleScholarGoogle Scholar | 17681719PubMed |

Hedblom GA, Reiland HA, Sylte MJ, Johnson TJ, Baumler DJ (2018) Segmented filamentous bacteria: metabolism meets immunity. Frontiers in Microbiology 9, 1991
Segmented filamentous bacteria: metabolism meets immunity.Crossref | GoogleScholarGoogle Scholar | 30197636PubMed |

Hermans PG, Morgan KL (2003) The epidemiology of necrotic enteritis in broiler chickens Research in Veterinary Science 74, 19
The epidemiology of necrotic enteritis in broiler chickensCrossref | GoogleScholarGoogle Scholar |

Higgins JP, Higgins SE, Wolfenden AD, Henderson SN, Torres-Rodriguez A, Vicente JL, Hargis BM, Tellez G (2010) Effect of lactic acid bacteria probiotic culture treatment timing on Salmonella enteritidis in neonatal broilers. Poultry Science 89, 243–247.
Effect of lactic acid bacteria probiotic culture treatment timing on Salmonella enteritidis in neonatal broilers.Crossref | GoogleScholarGoogle Scholar | 20075275PubMed |

Huff GR, Huff WE, Rath NC, El-Gohary FA, Zhou ZY, Shini S (2015) Efficacy of a novel prebiotic and a commercial probiotic in reducing mortality and production losses due to cold stress and Escherichia coli challenge of broiler chicks. Poultry Science 94, 918–926.
Efficacy of a novel prebiotic and a commercial probiotic in reducing mortality and production losses due to cold stress and Escherichia coli challenge of broiler chicks.Crossref | GoogleScholarGoogle Scholar | 25743418PubMed |

Islam SU (2016) Clinical Uses of Probiotics. Medicine 95, e2658
Clinical Uses of Probiotics.Crossref | GoogleScholarGoogle Scholar | 26844491PubMed |

Ivanov II, Littman DR (2010) Segmented filamentous bacteria take the stage. Mucosal Immunology 3, 209–212.
Segmented filamentous bacteria take the stage.Crossref | GoogleScholarGoogle Scholar | 20147894PubMed |

Jackson DN, Theiss AL (2020) Gut bacteria signaling to mitochondria in intestinal inflammation and cancer. Gut Microbes 11, 285–304.
Gut bacteria signaling to mitochondria in intestinal inflammation and cancer.Crossref | GoogleScholarGoogle Scholar | 30913966PubMed |

Jesse LG (2004) Alternative litter materials for growing poultry. North Carolina Poultry Industry Newsletter 1, 1–5.

Jeurissen SH, Lewis F, van der Klis JD, Mroz Z, Rebel JM, ter Huurne AA (2002) Parameters and techniques to determine intestinal health of poultry as constituted by immunity, integrity, and functionality. Current Issues in Intestinal Microbiology 3, 1–14.

Jia W, Slominski BA, Bruce HL, Blank G, Crow G, Jones O (2009) Effects of diet type and enzyme addition on growth performance and gut health of broiler chickens during subclinical Clostridium perfringens challenge. Poultry Science 88, 132–140.
Effects of diet type and enzyme addition on growth performance and gut health of broiler chickens during subclinical Clostridium perfringens challenge.Crossref | GoogleScholarGoogle Scholar | 19096067PubMed |

Johansson MEV, Sjövall H, Hansson GC (2013) The gastrointestinal mucus system in health and disease. Nature Reviews. Gastroenterology & Hepatology 10, 352–361.
The gastrointestinal mucus system in health and disease.Crossref | GoogleScholarGoogle Scholar |

Jou TS, Schneeberger EE, Nelson WJ (1998) Structural and functional regulation of tight junctions by RhoA and Rac1 small GTPases. The Journal of Cell Biology 142, 101–115.
Structural and functional regulation of tight junctions by RhoA and Rac1 small GTPases.Crossref | GoogleScholarGoogle Scholar | 9660866PubMed |

Kaldhusdal M, Hofshagen M (1992) Barley inclusion and avoparcin supplementation in broiler diets. 2. Clinical, pathological, and bacteriological findings in a mild form of necrotic enteritis. Poultry Science 71, 1145–1153.
Barley inclusion and avoparcin supplementation in broiler diets. 2. Clinical, pathological, and bacteriological findings in a mild form of necrotic enteritis.Crossref | GoogleScholarGoogle Scholar | 1641378PubMed |

Kaldhusdal M, Skjerve E (1996) Association between cereal contents in the diet and incidence of necrotic enteritis in broiler chickens in Norway. Preventive Veterinary Medicine 28, 1–16.
Association between cereal contents in the diet and incidence of necrotic enteritis in broiler chickens in Norway.Crossref | GoogleScholarGoogle Scholar |

Kaldhusdal M, Evensen Ø, Landsverk T (1995) Clostridium perfringens necrotizing enteritis of the fowl: a light microscopic, immunohistochemical and ultrastructural study of spontaneous disease. Avian Pathology 24, 421–433.
Clostridium perfringens necrotizing enteritis of the fowl: a light microscopic, immunohistochemical and ultrastructural study of spontaneous disease.Crossref | GoogleScholarGoogle Scholar | 18645799PubMed |

Kaldhusdal M, Benestad SL, Løvland A (2016) Epidemiologic aspects of necrotic enteritis in broiler chickens: disease occurrence and production performance. Avian Pathology 45, 271–274.
Epidemiologic aspects of necrotic enteritis in broiler chickens: disease occurrence and production performance.Crossref | GoogleScholarGoogle Scholar | 26956946PubMed |

Kang J, Pervaiz S (2012) Mitochondria: redox metabolism and dysfunction. Biochemistry Research International 2012, 896751
Mitochondria: redox metabolism and dysfunction.Crossref | GoogleScholarGoogle Scholar | 22593827PubMed |

Karimi Torshizi MA, Moghaddam AR, Rahimi S, Mojgani N (2010) Assessing the effect of administering probiotics in water or as a feed supplement on broiler performance and immune response. British Poultry Science 51, 178–184.
Assessing the effect of administering probiotics in water or as a feed supplement on broiler performance and immune response.Crossref | GoogleScholarGoogle Scholar | 20461578PubMed |

Kastl AJ, Terry NA, Wu GD, Albenberg LG (2020) The structure and function of the human small intestinal microbiota: current understanding and future directions. Cellular and Molecular Gastroenterology and Hepatology 9, 33–45.
The structure and function of the human small intestinal microbiota: current understanding and future directions.Crossref | GoogleScholarGoogle Scholar | 31344510PubMed |

Kechagia M, Basoulis D, Konstantopoulou S, Dimitriadi D, Gyftopoulou K, Skarmoutsou N, Fakiri EM (2013) Health benefits of probiotics: a review. ISRN Nutrition 2013, 481651
Health benefits of probiotics: a review.Crossref | GoogleScholarGoogle Scholar | 24959545PubMed |

Kim GB, Seo YM, Kim CH, Paik IK (2011) Effect of dietary prebiotic supplementation on the performance, intestinal microflora, and immune response of broilers. Poultry Science 90, 75–82.
Effect of dietary prebiotic supplementation on the performance, intestinal microflora, and immune response of broilers.Crossref | GoogleScholarGoogle Scholar | 21177446PubMed |

Kjekshus J (2015) Inflammation: friend and foe. EBioMedicine 2, 634–635.
Inflammation: friend and foe.Crossref | GoogleScholarGoogle Scholar | 26288833PubMed |

Klaasen HLBM, Koopman JP, Poelma FGJ, Beynen AC (1992) Intestinal, segmented, filamentous bacteria FEMS Microbiology Reviews 8, 165–179.
Intestinal, segmented, filamentous bacteriaCrossref | GoogleScholarGoogle Scholar |

Knudsen KEB (2014) Fiber and nonstarch polysaccharide content and variation in common crops used in broiler diets. Poultry Science 93, 2380–2393.
Fiber and nonstarch polysaccharide content and variation in common crops used in broiler diets.Crossref | GoogleScholarGoogle Scholar |

Kogut MH (2019) The effect of microbiome modulation on the intestinal health of poultry. Animal Feed Science and Technology 250, 32–40.
The effect of microbiome modulation on the intestinal health of poultry.Crossref | GoogleScholarGoogle Scholar |

Kogut MH, Arsenault RJ (2016) Editorial: Gut Health: the new paradigm in food animal production. Frontiers in Veterinary Science 3, 71
Editorial: Gut Health: the new paradigm in food animal production.Crossref | GoogleScholarGoogle Scholar | 27630994PubMed |

Kogut MH, Genovese KJ, Swaggerty CL, He H, Broom L (2018) Inflammatory phenotypes in the intestine of poultry: not all inflammation is created equal. Poultry Science 97, 2339–2346.
Inflammatory phenotypes in the intestine of poultry: not all inflammation is created equal.Crossref | GoogleScholarGoogle Scholar | 29618086PubMed |

Kollarcikova M, Kubasova T, Karasova D, Crhanova M, Cejkova D, Sisak F, Rychlik I (2019) Use of 16S rRNA gene sequencing for prediction of new opportunistic pathogens in chicken ileal and cecal microbiota. Poultry Science 98, 2347–2353.
Use of 16S rRNA gene sequencing for prediction of new opportunistic pathogens in chicken ileal and cecal microbiota.Crossref | GoogleScholarGoogle Scholar | 30624758PubMed |

Kraimi N, Dawkins M, Gebhardt-Henrich SG, Velge P, Rychlik I, Volf J, Creach P, Smith A, Colles F, Leterrier C (2019) Influence of the microbiota-gut-brain axis on behavior and welfare in farm animals: a review. Physiology & Behavior 210, 112658
Influence of the microbiota-gut-brain axis on behavior and welfare in farm animals: a review.Crossref | GoogleScholarGoogle Scholar |

Kumar S, Chen C, Indugu N, Werlang GO, Singh M, Kim WK, Thippareddi H (2018) Effect of antibiotic withdrawal in feed on chicken gut microbial dynamics, immunity, growth performance and prevalence of foodborne pathogens. PLoS One 13, e0192450
Effect of antibiotic withdrawal in feed on chicken gut microbial dynamics, immunity, growth performance and prevalence of foodborne pathogens.Crossref | GoogleScholarGoogle Scholar | 30576333PubMed |

La Fata G, Weber P, Mohajeri MH (2018) Probiotics and the gut immune system: indirect regulation. Probiotics and Antimicrobial Proteins 10, 11–21.
Probiotics and the gut immune system: indirect regulation.Crossref | GoogleScholarGoogle Scholar | 28861741PubMed |

Latorre JD, Hernandez-Velasco X, Bielke LR, Vicente JL, Wolfenden R, Menconi A, Hargis BM, Tellez G (2015) Evaluation of a Bacillus direct-fed microbial candidate on digesta viscosity, bacterial translocation, microbiota composition and bone mineralisation in broiler chickens fed on a rye-based diet. British Poultry Science 56, 723–732.
Evaluation of a Bacillus direct-fed microbial candidate on digesta viscosity, bacterial translocation, microbiota composition and bone mineralisation in broiler chickens fed on a rye-based diet.Crossref | GoogleScholarGoogle Scholar | 26539833PubMed |

Lee WJ, Hase K (2014) Gut microbiota-generated metabolites in animal health and disease. Nature Chemical Biology 10, 416–424.
Gut microbiota-generated metabolites in animal health and disease.Crossref | GoogleScholarGoogle Scholar | 24838170PubMed |

Lee KW, Lee SH, Lillehoj HS, Li GX, Jang SI, Babu US, Park MS, Kim DK, Lillehoj EP, Neumann AP, Rehberger TG, Siragusa GR (2010) Effects of direct-fed microbials on growth performance, gut morphometry, and immune characteristics in broiler chickens. Poultry Science 89, 203–216.
Effects of direct-fed microbials on growth performance, gut morphometry, and immune characteristics in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 20075271PubMed |

Lei K, Li YL, Yu DY, Rajput IR, Li WF (2013) Influence of dietary inclusion of Bacillus licheniformis on laying performance, egg quality, antioxidant enzyme activities, and intestinal barrier function of laying hens. Poultry Science 92, 2389–2395.
Influence of dietary inclusion of Bacillus licheniformis on laying performance, egg quality, antioxidant enzyme activities, and intestinal barrier function of laying hens.Crossref | GoogleScholarGoogle Scholar | 23960122PubMed |

Lescheid D (2014) Probiotics as regulators of inflammation: a review. Functional Foods in Health and Disease 4, 299–311.
Probiotics as regulators of inflammation: a review.Crossref | GoogleScholarGoogle Scholar |

Li X, Zhang D, Bryden WL (2017) Calcium and phosphorus metabolism and nutrition of poultry: are current diets formulated in excess? Animal Production Science 57, 2304–2310.
Calcium and phosphorus metabolism and nutrition of poultry: are current diets formulated in excess?Crossref | GoogleScholarGoogle Scholar |

Liao N, Yin Y, Sun G, Xiang C, Liu D, Yu HD, Wang X (2012) Colonization and distribution of segmented filamentous bacteria (SFB) in chicken gastrointestinal tract and their relationship with host immunity. FEMS Microbiology Ecology 81, 395–406.
Colonization and distribution of segmented filamentous bacteria (SFB) in chicken gastrointestinal tract and their relationship with host immunity.Crossref | GoogleScholarGoogle Scholar | 22429007PubMed |

Liu Y, Fatheree NY, Mangalat N, Rhoads JM (2010) Human-derived probiotic Lactobacillus reuteri strains differentially reduce intestinal inflammation. American Journal of Physiology. Gastrointestinal and Liver Physiology 299, G1087–G1096.
Human-derived probiotic Lactobacillus reuteri strains differentially reduce intestinal inflammation.Crossref | GoogleScholarGoogle Scholar | 20798357PubMed |

Lloyd AB, Cumming RB, Kent RD (1977) Prevention of Salmonella typhimurium infection in poultry by pretreatment of chickens and poults with intestinal extracts. Australian Veterinary Journal 53, 82–87.
Prevention of Salmonella typhimurium infection in poultry by pretreatment of chickens and poults with intestinal extracts.Crossref | GoogleScholarGoogle Scholar | 324465PubMed |

Long JR, Truscott RB (1976) Necrotic enteritis in broiler chickens. III. Reproduction of the disease. Canadian Journal of Comparative Medicine 40, 53–59.

Lu J, Idris U, Harmon B, Hofacre C, Maurer JJ, Lee MD (2003) Diversity and succession of the intestinal bacterial community of the maturing broiler chicken. Applied and Environmental Microbiology 69, 6816–6824.
Diversity and succession of the intestinal bacterial community of the maturing broiler chicken.Crossref | GoogleScholarGoogle Scholar | 14602645PubMed |

Lutful Kabir SM (2009) The role of probiotics in the poultry industry. International Journal of Molecular Sciences 10, 3531–3546.
The role of probiotics in the poultry industry.Crossref | GoogleScholarGoogle Scholar | 20111681PubMed |

Macfarlane GT, Macfarlane S (2012) Bacteria, colonic fermentation, and gastrointestinal health. Journal of AOAC International 95, 50–60.
Bacteria, colonic fermentation, and gastrointestinal health.Crossref | GoogleScholarGoogle Scholar | 22468341PubMed |

Mack DR, Michail S, Wei S, McDougall L, Hollingsworth MA (1999) Probiotics inhibit enteropathogenic E. coli adherence in vitro by inducing intestinal mucin gene expression. The American Journal of Physiology 276, G941–G950.

MarketsandMarkets (2019) Probiotics in animal feed market by livestock (poultry, ruminants, swine, aquaculture, pets), source (bacteria [Lactobacilli, Streptococcus thermophilus, Bifidobacteria] and yeast & fungi), form (dry and liquid), and region: global forecast to 2025. Report. Available at https://www.marketsandmarkets.com/Market-Reports/probiotics-animal-feed-market-85832335.html [Verified 2 December 2020]

Martin Manuel P, Elena B, Carolina MG, Gabriela P (2017) Oral probiotics supplementation can stimulate the immune system in a stress process. Journal of Nutrition & Intermediary Metabolism 8, 29–40.
Oral probiotics supplementation can stimulate the immune system in a stress process.Crossref | GoogleScholarGoogle Scholar |

Menconi A, Wolfenden AD, Shivaramaiah S, Terraes JC, Urbano T, Kuttel J, Kremer C, Hargis BM, Tellez G (2011) Effect of lactic acid bacteria probiotic culture for the treatment of Salmonella enterica serovar Heidelberg in neonatal broiler chickens and turkey poults. Poultry Science 90, 561–565.
Effect of lactic acid bacteria probiotic culture for the treatment of Salmonella enterica serovar Heidelberg in neonatal broiler chickens and turkey poults.Crossref | GoogleScholarGoogle Scholar | 21325226PubMed |

Minelli EB, Benini A (2008) Relationship between number of bacteria and their probiotic effects. Microbial Ecology in Health and Disease 20, 180–183.
Relationship between number of bacteria and their probiotic effects.Crossref | GoogleScholarGoogle Scholar |

Morelli L, Capurso L (2012) FAO/WHO Guidelines on probiotics: 10 years later. Journal of Clinical Gastroenterology 46, S1–S2.
FAO/WHO Guidelines on probiotics: 10 years later.Crossref | GoogleScholarGoogle Scholar | 22955349PubMed |

Mountzouris KC, Tsitrsikos P, Palamidi I, Arvaniti A, Mohnl M, Schatzmayr G, Fegeros K (2010) Effects of probiotic inclusion levels in broiler nutrition on growth performance, nutrient digestibility, plasma immunoglobulins, and cecal microflora composition. Poultry Science 89, 58–67.
Effects of probiotic inclusion levels in broiler nutrition on growth performance, nutrient digestibility, plasma immunoglobulins, and cecal microflora composition.Crossref | GoogleScholarGoogle Scholar | 20008803PubMed |

Mountzouris KC, Palamidi I, Paraskeuas V, Griela E, Fegeros K (2019) Dietary probiotic form modulates broiler gut microbiota indices and expression of gut barrier genes including essential components for gut homeostasis. Journal of Animal Physiology and Animal Nutrition 103, 1143–1159.
Dietary probiotic form modulates broiler gut microbiota indices and expression of gut barrier genes including essential components for gut homeostasis.Crossref | GoogleScholarGoogle Scholar | 31087706PubMed |

Mutuş R, Kocabagli N, Alp M, Acar N, Eren M, Gezen SS (2006) The effect of dietary probiotic supplementation on tibial bone characteristics and strength in broilers. Poultry Science 85, 1621–1625.
The effect of dietary probiotic supplementation on tibial bone characteristics and strength in broilers.Crossref | GoogleScholarGoogle Scholar | 16977848PubMed |

Naidu AS, Bidlack WR, Clemens RA (1999) Probiotic spectra of lactic acid bacteria (LAB). Critical Reviews in Food Science and Nutrition 39, 13–126.
Probiotic spectra of lactic acid bacteria (LAB).Crossref | GoogleScholarGoogle Scholar | 10028126PubMed |

Niewold TA (2007) The nonantibiotic anti-inflammatory effect of antimicrobial growth promoters, the real mode of action: a hypothesis. Poultry Science 86, 605–609.
The nonantibiotic anti-inflammatory effect of antimicrobial growth promoters, the real mode of action: a hypothesis.Crossref | GoogleScholarGoogle Scholar | 17369528PubMed |

Nurmi E, Rantala M (1973) New aspects of Salmonella infection in broiler production. Nature 241, 210–211.
New aspects of Salmonella infection in broiler production.Crossref | GoogleScholarGoogle Scholar | 4700893PubMed |

Oakley BB, Lillehoj HS, Kogut MH, Kim WK, Maurer JJ, Pedroso A, Lee MD, Collett SR, Johnson TJ, Cox NA (2014) The chicken gastrointestinal microbiome. FEMS Microbiology Letters 360, 100–112.
The chicken gastrointestinal microbiome.Crossref | GoogleScholarGoogle Scholar | 25263745PubMed |

Olkowski AA, Wojnarowicz C, Chirino-Trejo M, Laarveld B, Sawicki G (2008) Sub-clinical necrotic enteritis in broiler chickens: novel etiological consideration based on ultra-structural and molecular changes in the intestinal tissue. Research in Veterinary Science 85, 543–553.
Sub-clinical necrotic enteritis in broiler chickens: novel etiological consideration based on ultra-structural and molecular changes in the intestinal tissue.Crossref | GoogleScholarGoogle Scholar | 18359497PubMed |

Olnood CG, Beski SSM, Choct M, Iji PA (2015a) Novel probiotics: their effects on growth performance, gut development, microbial community and activity of broiler chickens. Animal Nutrition 1, 184–191.
Novel probiotics: their effects on growth performance, gut development, microbial community and activity of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 29767136PubMed |

Olnood CG, Beski SSM, Iji PA, Choct M (2015b) Delivery routes for probiotics: effects on broiler performance, intestinal morphology and gut microflora. Animal Nutrition 1, 192–202.
Delivery routes for probiotics: effects on broiler performance, intestinal morphology and gut microflora.Crossref | GoogleScholarGoogle Scholar | 29767168PubMed |

Palamidi I, Fegeros K, Mohnl M, Abdelrahman WHA, Schatzmayr G, Theodoropoulos G, Mountzouris KC (2016) Probiotic form effects on growth performance, digestive function, and immune related biomarkers in broilers. Poultry Science 95, 1598–1608.
Probiotic form effects on growth performance, digestive function, and immune related biomarkers in broilers.Crossref | GoogleScholarGoogle Scholar | 26944970PubMed |

Pan D, Yu Z (2014) Intestinal microbiome of poultry and its interaction with host and diet. Gut Microbes 5, 108–119.
Intestinal microbiome of poultry and its interaction with host and diet.Crossref | GoogleScholarGoogle Scholar | 24256702PubMed |

Parish WE (1961) Necrotic enteritis in the fowl (Gallus gallus domesticus). I. Histopathology of the disease and isolation of a strain of Clostridium welchii. Journal of Comparative Pathology 71, 377–393.
Necrotic enteritis in the fowl (Gallus gallus domesticus). I. Histopathology of the disease and isolation of a strain of Clostridium welchii.Crossref | GoogleScholarGoogle Scholar | 14483884PubMed |

Park JH, Kim IH (2015) The effects of the supplementation of Bacillus subtilis RX7 and B2A strains on the performance, blood profiles, intestinal Salmonella concentration, noxious gas emission, organ weight and breast meat quality of broiler challenged with Salmonella typhimurium. Journal of Animal Physiology and Animal Nutrition 99, 326–334.
The effects of the supplementation of Bacillus subtilis RX7 and B2A strains on the performance, blood profiles, intestinal Salmonella concentration, noxious gas emission, organ weight and breast meat quality of broiler challenged with Salmonella typhimurium.Crossref | GoogleScholarGoogle Scholar | 25244020PubMed |

Park SS, Lillehoj HS, Allen PC, Park DW, FitzCoy S, Bautista DA, Lillehoje EP (2008) Immunopathology and cytokine responses in broiler chickens coinfected with Eimeria maxima and Clostridium perfringens with the use of an animal model of necrotic enteritis. Avian Diseases 52, 14–22.
Immunopathology and cytokine responses in broiler chickens coinfected with Eimeria maxima and Clostridium perfringens with the use of an animal model of necrotic enteritis.Crossref | GoogleScholarGoogle Scholar | 18459290PubMed |

Park JW, Jeong JS, Lee SI, Kim IH (2016) Effect of dietary supplementation with a probiotic (Enterococcus faecium) on production performance, excreta microflora, ammonia emission, and nutrient utilization in ISA brown laying hens. Poultry Science 95, 2829–2835.
Effect of dietary supplementation with a probiotic (Enterococcus faecium) on production performance, excreta microflora, ammonia emission, and nutrient utilization in ISA brown laying hens.Crossref | GoogleScholarGoogle Scholar | 27422665PubMed |

Park I, Lee Y, Goo D, Zimmerman NP, Smith AH, Rehberger T, Lillehoj HS (2020) The effects of dietary Bacillus subtilis supplementation, as an alternative to antibiotics, on growth performance, intestinal immunity, and epithelial barrier integrity in broiler chickens infected with Eimeria maxima. Poultry Science 99, 725–733.
The effects of dietary Bacillus subtilis supplementation, as an alternative to antibiotics, on growth performance, intestinal immunity, and epithelial barrier integrity in broiler chickens infected with Eimeria maxima.Crossref | GoogleScholarGoogle Scholar | 32036975PubMed |

Peng M, Tabashsum Z, Anderson M, Truong A, Houser AK, Padilla J, Akmel A, Bhatti J, Rahaman SO, Biswas D (2020) Effectiveness of probiotics, prebiotics, and prebiotic-like components in common functional foods. Comprehensive Reviews in Food Science and Food Safety 19, 1908–1933.
Effectiveness of probiotics, prebiotics, and prebiotic-like components in common functional foods.Crossref | GoogleScholarGoogle Scholar | 33337097PubMed |

Pereira R, Bortoluzzi C, Durrer A, Fagundes NS, Pedroso AA, Rafael JM, Perim JEdL, Zavarize KC, Napty GS, Andreote FD, Costa DP, Menten JFM (2019) Performance and intestinal microbiota of chickens receiving probiotic in the feed and submitted to antibiotic therapy. Journal of Animal Physiology and Animal Nutrition 103, 72–86.
Performance and intestinal microbiota of chickens receiving probiotic in the feed and submitted to antibiotic therapy.Crossref | GoogleScholarGoogle Scholar | 30485573PubMed |

Persichetti E, De Michele A, Codini M, Traina G (2014) Antioxidative capacity of Lactobacillus fermentum LF31 evaluated in vitro by oxygen radical absorbance capacity assay. Nutrition 30, 936–938.
Antioxidative capacity of Lactobacillus fermentum LF31 evaluated in vitro by oxygen radical absorbance capacity assay.Crossref | GoogleScholarGoogle Scholar | 24985014PubMed |

Plaza-Díaz J, Ruiz-Ojeda FJ, Vilchez-Padial LM, Gil A (2017) Evidence of the anti-inflammatory effects of probiotics and synbiotics in intestinal chronic diseases. Nutrients 9, 555
Evidence of the anti-inflammatory effects of probiotics and synbiotics in intestinal chronic diseases.Crossref | GoogleScholarGoogle Scholar |

Pluske JR, Miller DW, Sterndale SO, Turpin DL (2019) Associations between gastrointestinal-tract function and the stress response after weaning in pigs. Animal Production Science 59, 2015–2022.
Associations between gastrointestinal-tract function and the stress response after weaning in pigs.Crossref | GoogleScholarGoogle Scholar |

Prado-Rebolledo OF, Delgado-Machuca JdJ, Macedo-Barragan RJ, Garcia-Márquez LJ, Morales-Barrera JE, Latorre JD, Hernandez-Velasco X, Tellez G (2017) Evaluation of a selected lactic acid bacteria-based probiotic on Salmonella enterica serovar Enteritidis colonization and intestinal permeability in broiler chickens. Avian Pathology 46, 90–94.
Evaluation of a selected lactic acid bacteria-based probiotic on Salmonella enterica serovar Enteritidis colonization and intestinal permeability in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 27545145PubMed |

Prescott JF, Sivendra R, Barnum DA (1978) The use of bacitracin in the prevention and treatment of experimentally-induced necrotic enteritis in the chicken. The Canadian Veterinary Journal 19, 181–183.

Quigley EM (2016) Leaky gut: concept or clinical entity? Current Opinion in Gastroenterology 32, 74–79.
Leaky gut: concept or clinical entity?Crossref | GoogleScholarGoogle Scholar | 26760399PubMed |

Rao RK, Samak G (2013) Protection and restitution of gut barrier by probiotics: nutritional and clinical implications. Current Nutrition and Food Science 9, 99–107.
Protection and restitution of gut barrier by probiotics: nutritional and clinical implications.Crossref | GoogleScholarGoogle Scholar | 24353483PubMed |

Ravindran V (2013) Feed enzymes: the science, practice, and metabolic realities. Journal of Applied Poultry Research 22, 628–636.
Feed enzymes: the science, practice, and metabolic realities.Crossref | GoogleScholarGoogle Scholar |

Riddell C, Kong XM (1992) The influence of diet on necrotic enteritis in broiler chickens. Avian Diseases 36, 499–503.
The influence of diet on necrotic enteritis in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 1417581PubMed |

Rodgers NJ, Swick RA, Geier MS, Moore RJ, Choct M, Wu SB (2015) A multifactorial analysis of the extent to which Eimeria and fishmeal predispose broiler chickens to necrotic enteritis. Avian Diseases 59, 38–45.
A multifactorial analysis of the extent to which Eimeria and fishmeal predispose broiler chickens to necrotic enteritis.Crossref | GoogleScholarGoogle Scholar | 26292532PubMed |

Rowland I, Gibson G, Heinken A, Scott K, Swann J, Thiele I, Tuohy K (2018) Gut microbiota functions: metabolism of nutrients and other food components. European Journal of Nutrition 57, 1–24.
Gut microbiota functions: metabolism of nutrients and other food components.Crossref | GoogleScholarGoogle Scholar | 28393285PubMed |

Rubartelli A, Lotze MT, Latz E, Manfredi A (2013) Mechanisms of sterile inflammation. Frontiers in Immunology 4, 398
Mechanisms of sterile inflammation.Crossref | GoogleScholarGoogle Scholar | 24319446PubMed |

Rychlik I (2020) Composition and function of chicken gut microbiota. Animals (Basel) 10, 103
Composition and function of chicken gut microbiota.Crossref | GoogleScholarGoogle Scholar |

Salim HM, Kang HK, Akter N, Kim DW, Kim JH, Kim MJ, Na JC, Jong HB, Choi HC, Suh OS, Kim WK (2013) Supplementation of direct-fed microbials as an alternative to antibiotic on growth performance, immune response, cecal microbial population, and ileal morphology of broiler chickens. Poultry Science 92, 2084–2090.
Supplementation of direct-fed microbials as an alternative to antibiotic on growth performance, immune response, cecal microbial population, and ileal morphology of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 23873556PubMed |

Scanes CG, Pierzchala-Koziec K (2014) Biology of the gastrointestinal tract in poultry. Avian Biology Research 7, 193–222.
Biology of the gastrointestinal tract in poultry.Crossref | GoogleScholarGoogle Scholar |

Sczesnak A, Segata N, Qin X, Gevers D, Petrosino JF, Huttenhower C, Littman DR, Ivanov II (2011) The genome of Th17 cell-inducing segmented filamentous bacteria reveals extensive auxotrophy and adaptations to the intestinal environment. Cell Host & Microbe 10, 260–272.
The genome of Th17 cell-inducing segmented filamentous bacteria reveals extensive auxotrophy and adaptations to the intestinal environment.Crossref | GoogleScholarGoogle Scholar |

Serhan CN, Brain SD, Buckley CD, Gilroy DW, Haslett C, O’Neill LAJ, Perretti M, Rossi AG, Wallace JL (2007) Resolution of inflammation: state of the art, definitions and terms. The FASEB Journal 21, 325–332.
Resolution of inflammation: state of the art, definitions and terms.Crossref | GoogleScholarGoogle Scholar | 17267386PubMed |

Shang Y, Kumar S, Oakley B, Kim WK (2018) Chicken gut microbiota: importance and detection technology. Frontiers in Veterinary Science 5, 254
Chicken gut microbiota: importance and detection technology.Crossref | GoogleScholarGoogle Scholar | 30406117PubMed |

Shini S, Shini A, Blackall PJ (2013) The potential for probiotics to prevent reproductive tract lesions in free-range laying hens. Animal Production Science 53, 1298–1308.
The potential for probiotics to prevent reproductive tract lesions in free-range laying hens.Crossref | GoogleScholarGoogle Scholar |

Shini S, Aland RC, Bryden WL (2019) The abundance and morphology of mitochondria in enterocytes of chickens exposed to necrotic enteritis and treated with a probiotic. In ‘Proceedings of the 7th International Conference on Poultry Intestinal Health’, 3–5 April 2019, Rome, Italy. p. 242.

Shini S, Aland RC, Dart PJ, Callaghan MJ, Speight RE, Bryden WL (2020a) Ultrastructural changes in the ileal mucosa of broilers exposed to necrotic enteritis and Bacillus amyloliquefaciens H57. In ‘Proceedings of the 31st Annual Australian Poultry Science Symposium’, 16–19 February 2020, Sydney, Australia. p. 130. (Poultry Research Foundation, University of Sydney: Sydney, NSW, Australia)

Shini S, Zhang D, Aland RC, Li X, Dart PJ, Callaghan MJ, Speight RE, Bryden WL (2020b) Probiotic Bacillus amyloliquefaciens H57 ameliorates subclinical necrotic enteritis in broiler chicks by maintaining intestinal mucosal integrity and improving feed efficiency. Poultry Science 99, 4278–4293.
Probiotic Bacillus amyloliquefaciens H57 ameliorates subclinical necrotic enteritis in broiler chicks by maintaining intestinal mucosal integrity and improving feed efficiency.Crossref | GoogleScholarGoogle Scholar | 32867972PubMed |

Shini S, Aland RC, Bryden WL (2021) Avian intestinal ultrastructure changes provide insight into the pathogenesis of enteric diseases and probiotic mode of action. Scientific Reports 11, 167
Avian intestinal ultrastructure changes provide insight into the pathogenesis of enteric diseases and probiotic mode of action.Crossref | GoogleScholarGoogle Scholar | 33420315PubMed |

Skinner JT, Bauer S, Young V, Pauling G, Wilson J (2010) An economic analysis of the impact of subclinical (mild) necrotic enteritis in broiler chickens. Avian Diseases 54, 1237–1240.
An economic analysis of the impact of subclinical (mild) necrotic enteritis in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 21313845PubMed |

Smith J (2014) A review of avian probiotics. Journal of Avian Medicine and Surgery 28, 87–94.
A review of avian probiotics.Crossref | GoogleScholarGoogle Scholar | 25115036PubMed |

Smyth JA (2016) Pathology and diagnosis of necrotic enteritis: is it clear-cut? Avian Pathology 45, 282–287.
Pathology and diagnosis of necrotic enteritis: is it clear-cut?Crossref | GoogleScholarGoogle Scholar | 26981703PubMed |

Soerjadi AS, Lloyd AB, Cumming RB (1978) Streptococcus faecalis, a bacterial isolate which protects young chickens from enteric invasion by Salmonella. Australian Veterinary Journal 54, 549–550.
Streptococcus faecalis, a bacterial isolate which protects young chickens from enteric invasion by Salmonella.Crossref | GoogleScholarGoogle Scholar | 111659PubMed |

Stanley D, Hughes RJ, Moore RJ (2014) Microbiota of the chicken gastrointestinal tract: influence on health, productivity and disease. Applied Microbiology and Biotechnology 98, 4301–4310.
Microbiota of the chicken gastrointestinal tract: influence on health, productivity and disease.Crossref | GoogleScholarGoogle Scholar | 24643736PubMed |

Sun J, Wang Y, Li N, Zhong H, Xu H, Zhu Q, Liu Y (2018) Comparative analysis of the gut microbial composition and meat flavor of two chicken breeds in different rearing patterns. BioMed Research International 2018, 4343196
Comparative analysis of the gut microbial composition and meat flavor of two chicken breeds in different rearing patterns.Crossref | GoogleScholarGoogle Scholar | 30643812PubMed |

Swaggerty CL, Callaway TR, Kogut MH, Piva A, Grilli E (2019) Modulation of the immune response to improve health and reduce foodborne pathogens in poultry. Microorganisms 7, 65
Modulation of the immune response to improve health and reduce foodborne pathogens in poultry.Crossref | GoogleScholarGoogle Scholar |

Tanabe S (2013) The effect of probiotics and gut microbiota on Th17 cells. International Reviews of Immunology 32, 511–525.
The effect of probiotics and gut microbiota on Th17 cells.Crossref | GoogleScholarGoogle Scholar | 24094077PubMed |

Tarradas J, Tous N, Esteve-Garcia E, Brufau AJ (2020) The control of intestinal inflammation: a major objective in the research of probiotic strains as alternatives to antibiotic growth promoters in poultry. Microorganisms 8, 148
The control of intestinal inflammation: a major objective in the research of probiotic strains as alternatives to antibiotic growth promoters in poultry.Crossref | GoogleScholarGoogle Scholar |

Teng P-Y, Kim WK (2018) Review: roles of prebiotics in intestinal ecosystem of broilers. Frontiers in Veterinary Science 5, 245
Review: roles of prebiotics in intestinal ecosystem of broilers.Crossref | GoogleScholarGoogle Scholar | 30425993PubMed |

Teshfam M, Rahbari S (2003) Alteration in small intestinal structure induced by experimental subclinical coccidiosis in chicken. Journal of Applied Animal Research 24, 33–39.
Alteration in small intestinal structure induced by experimental subclinical coccidiosis in chicken.Crossref | GoogleScholarGoogle Scholar |

Ticho AL, Malhotra P, Dudeja PK, Gill RK, Alrefai WA (2019) Intestinal absorption of bile acids in health and disease. Comprative Physiology 10, 21–56.
Intestinal absorption of bile acids in health and disease.Crossref | GoogleScholarGoogle Scholar |

Tomaszewska E, Kwiecień M, Dobrowolski P, Klebaniuk R, Muszyński S, Olcha M, Blicharski T, Grela ER (2018) Dose-dependent effects of probiotic supplementation on bone characteristics and mineralisation in meat-type female turkeys. Animal Production Science 58, 507–516.
Dose-dependent effects of probiotic supplementation on bone characteristics and mineralisation in meat-type female turkeys.Crossref | GoogleScholarGoogle Scholar |

Turk DE (1972) Protozoan parasitic infections of the chick intestine and protein digestion and absorption. The Journal of Nutrition 102, 1217–1221.
Protozoan parasitic infections of the chick intestine and protein digestion and absorption.Crossref | GoogleScholarGoogle Scholar | 5057208PubMed |

Tytgat HLP, Nobrega FL, van der Oost J, de Vos WM (2019) Bowel biofilms: tipping points between a healthy and compromised gut? Trends in Microbiology 27, 17–25.
Bowel biofilms: tipping points between a healthy and compromised gut?Crossref | GoogleScholarGoogle Scholar | 30219265PubMed |

Ulluwishewa D, Anderson RC, McNabb WC, Moughan PJ, Wells JM, Roy NC (2011) Regulation of tight junction permeability by intestinal bacteria and dietary components. The Journal of Nutrition 141, 769–776.
Regulation of tight junction permeability by intestinal bacteria and dietary components.Crossref | GoogleScholarGoogle Scholar | 21430248PubMed |

Vancamelbeke M, Vermeire S (2017) The intestinal barrier: a fundamental role in health and disease. Expert Review of Gastroenterology & Hepatology 11, 821–834.
The intestinal barrier: a fundamental role in health and disease.Crossref | GoogleScholarGoogle Scholar |

Villageliũ DN, Lyte M (2017) Microbial endocrinology: why the intersection of microbiology and neurobiology matters to poultry health. Poultry Science 96, 2501–2508.
Microbial endocrinology: why the intersection of microbiology and neurobiology matters to poultry health.Crossref | GoogleScholarGoogle Scholar | 29050443PubMed |

Wang Z, Yu Q, Fu J, Liang J, Yang Q (2013) Immune responses of chickens inoculated with recombinant Lactobacillus expressing the haemagglutinin of the avian influenza virus. Journal of Applied Microbiology 115, 1269–1277.
Immune responses of chickens inoculated with recombinant Lactobacillus expressing the haemagglutinin of the avian influenza virus.Crossref | GoogleScholarGoogle Scholar | 23937220PubMed |

Wang S, Zeng X, Yang Q, Qiao S (2016) Antimicrobial peptides as potential alternatives to antibiotics in food animal industry. International Journal of Molecular Sciences 17, 603
Antimicrobial peptides as potential alternatives to antibiotics in food animal industry.Crossref | GoogleScholarGoogle Scholar |

Wang Y, Wu Y, Wang Y, Fu A, Gong L, Li W, Li Y (2017) Bacillus amyloliquefaciens SC06 alleviates the oxidative stress of IPEC-1 via modulating Nrf2/Keap1 signaling pathway and decreasing ROS production. Applied Microbiology and Biotechnology 101, 3015–3026.
Bacillus amyloliquefaciens SC06 alleviates the oxidative stress of IPEC-1 via modulating Nrf2/Keap1 signaling pathway and decreasing ROS production.Crossref | GoogleScholarGoogle Scholar | 27957629PubMed |

Wang J, Ishfaq M, Guo Y, Chen C, Li J (2020) Assessment of probiotic properties of Lactobacillus salivarius isolated from chickens as feed additives. Frontiers in Veterinary Science 7, 415
Assessment of probiotic properties of Lactobacillus salivarius isolated from chickens as feed additives.Crossref | GoogleScholarGoogle Scholar | 32766298PubMed |

Watkins BA, Kratzer FH (1983) Effect of oral dosing of Lactobacillus strains on gut colonization and liver biotin in broiler chicks. Poultry Science 62, 2088–2094.
Effect of oral dosing of Lactobacillus strains on gut colonization and liver biotin in broiler chicks.Crossref | GoogleScholarGoogle Scholar | 6415641PubMed |

Watnick PI, Jugder B-E (2020) Microbial control of intestinal homeostasis via enteroendocrine cell innate immune signalling. Trends in Microbiology 28, 141–149.
Microbial control of intestinal homeostasis via enteroendocrine cell innate immune signalling.Crossref | GoogleScholarGoogle Scholar | 31699645PubMed |

Weese JS, Martin H (2011) Assessment of commercial probiotic bacterial contents and label accuracy. The Canadian Veterinary Journal. La Revue Veterinaire Canadienne 52, 43–46.

Wideman RF, Hamal KR, Stark JM, Blankenship J, Lester H, Mitchell KN, Lorenzoni G, Pevzner I (2012) A wire-flooring model for inducing lame-ness in broilers: evaluation of probiotics as a prophylactic treatment. Poultry Science 91, 870–883.
A wire-flooring model for inducing lame-ness in broilers: evaluation of probiotics as a prophylactic treatment.Crossref | GoogleScholarGoogle Scholar | 22399726PubMed |

Wilkins T, Sequoia J (2017) Probiotics for gastrointestinal conditions: a summary of the evidence. American Family Physician 96, 170–178.

Williams RB (2005) Intercurrent coccidiosis and necrotic enteritis of chickens: rational, integrated disease management by maintenance of gut integrity. Avian Pathology 34, 159–180.
Intercurrent coccidiosis and necrotic enteritis of chickens: rational, integrated disease management by maintenance of gut integrity.Crossref | GoogleScholarGoogle Scholar | 16191699PubMed |

Witlock DR, Ruff MD (1977) Comparison of the intestinal surface damage caused by Eimeria mivati, E. necatrix, E. maxima, E. brunetti, and E. acervulina by scanning electron microscopy. The Journal of Parasitology 63, 193–199.
Comparison of the intestinal surface damage caused by Eimeria mivati, E. necatrix, E. maxima, E. brunetti, and E. acervulina by scanning electron microscopy.Crossref | GoogleScholarGoogle Scholar | 859075PubMed |

Wu SB, Rodgers N, Choct M (2010) Optimized necrotic enteritis model producing clinical and subclinical infection of Clostridium perfringens in broiler chickens. Avian Diseases 54, 1058–1065.
Optimized necrotic enteritis model producing clinical and subclinical infection of Clostridium perfringens in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 20945788PubMed |

Wu BQ, Zhang T, Guo LQ, Lin JF (2011) Effects of Bacillus subtilis KD1 on broiler intestinal flora. Poultry Science 90, 2493–2499.
Effects of Bacillus subtilis KD1 on broiler intestinal flora.Crossref | GoogleScholarGoogle Scholar | 22010234PubMed |

Wu QJ, Zhou YM, Wu YN, Zhang LL, Wang T (2013) The effects of natural and modified clinoptilolite on intestinal barrier function and immune response to LPS in broiler chickens. Veterinary Immunology and Immunopathology 153, 70–76.
The effects of natural and modified clinoptilolite on intestinal barrier function and immune response to LPS in broiler chickens.Crossref | GoogleScholarGoogle Scholar | 23453767PubMed |

Wu SB, Stanley D, Rodgers N, Swick RA, Moore RJ (2014) Two necrotic enteritis predisposing factors, dietary fishmeal and Eimeria infection, induce large changes in the caecal microbiota of broiler chickens. Veterinary Microbiology 169, 188–197.
Two necrotic enteritis predisposing factors, dietary fishmeal and Eimeria infection, induce large changes in the caecal microbiota of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 24522272PubMed |

Xiang Q, Wang C, Zhang H, Lai W, Wei H, Peng J (2019) Effects of different probiotics on laying performance, egg quality, oxidative status, and gut health in laying hens. Animals (Basel) 9, 1110
Effects of different probiotics on laying performance, egg quality, oxidative status, and gut health in laying hens.Crossref | GoogleScholarGoogle Scholar |

Yadav S, Jha R (2019) Strategies to modulate the intestinal microbiota and their effects on nutrient utilization, performance, and health of poultry. Journal of Animal Science and Biotechnology 10, 2
Strategies to modulate the intestinal microbiota and their effects on nutrient utilization, performance, and health of poultry.Crossref | GoogleScholarGoogle Scholar | 30651986PubMed |

Yan FF, Mohammed AA, Murugesan GR, Cheng HW (2019) Effects of a dietary synbiotic inclusion on bone health in broilers subjected to cyclic heat stress episodes. Poultry Science 98, 1083–1089.
Effects of a dietary synbiotic inclusion on bone health in broilers subjected to cyclic heat stress episodes.Crossref | GoogleScholarGoogle Scholar | 30476217PubMed |

Zaghari M, Sarani P, Hajati H (2020) Comparison of two probiotic preparations on growth performance, intestinal microbiota, nutrient digestibility and cytokine gene expression in broiler chickens. Journal of Applied Animal Research 48, 166–175.
Comparison of two probiotic preparations on growth performance, intestinal microbiota, nutrient digestibility and cytokine gene expression in broiler chickens.Crossref | GoogleScholarGoogle Scholar |

Zarei A, Lavvaf A, Motamedi Motlagh M (2018) Effects of probiotic and whey powder supplementation on growth performance, microflora population, and ileum morphology in broilers. Journal of Applied Animal Research 46, 840–844.
Effects of probiotic and whey powder supplementation on growth performance, microflora population, and ileum morphology in broilers.Crossref | GoogleScholarGoogle Scholar |

Zekarias B, Stockhofe-Zurwieden N, Post J, Balk F, van Reenen C, Gruys E, Rebel JMJ (2005) The pathogenesis of and susceptibility to malabsorption syndrome in broilers is associated with heterophil influx into the intestinal mucosa and epithelial apoptosis. Avian Pathology 34, 402–407.
The pathogenesis of and susceptibility to malabsorption syndrome in broilers is associated with heterophil influx into the intestinal mucosa and epithelial apoptosis.Crossref | GoogleScholarGoogle Scholar | 16236573PubMed |

Zhang JL, Xie QM, Ji J, Yang WH, Wu YB, Li C, Ma JY, Bi YZ (2012) Different combinations of probiotics improve the production performance, egg quality, and immune response of layer hens. Poultry Science 91, 2755–2760.
Different combinations of probiotics improve the production performance, egg quality, and immune response of layer hens.Crossref | GoogleScholarGoogle Scholar | 23091128PubMed |

Zhao X, Guo Y, Guo S, Tan J (2013) Effects of Clostridium butyricum and Enterococcus faecium on growth performance, lipid metabolism, and cecal microbiota of broiler chickens. Applied Microbiology and Biotechnology 97, 6477–6488.
Effects of Clostridium butyricum and Enterococcus faecium on growth performance, lipid metabolism, and cecal microbiota of broiler chickens.Crossref | GoogleScholarGoogle Scholar | 23666481PubMed |

Zheng A, Luo J, Meng K, Li J, Zhang S, Li K, Liu G, Cai H, Bryden WL, Yao B (2014) Proteome changes underpin improved meat quality and yield of chickens (Gallus gallus) fed the probiotic Enterococcus faecium. BMC Genomics 15, 1167
Proteome changes underpin improved meat quality and yield of chickens (Gallus gallus) fed the probiotic Enterococcus faecium.Crossref | GoogleScholarGoogle Scholar | 25532559PubMed |

Zheng A, Luo J, Meng K, Li J, Bryden WL, Chang W, Zhang S, Wang LXN, Guohua Liu G, Yao B (2016) Probiotic (Enterococcus faecium) induced responses of the hepatic proteome improves metabolic efficiency of broiler chickens (Gallus gallus). BMC Genomics 17, 89
Probiotic (Enterococcus faecium) induced responses of the hepatic proteome improves metabolic efficiency of broiler chickens (Gallus gallus).Crossref | GoogleScholarGoogle Scholar | 26830196PubMed |

Zommiti M, Chikindas ML, Ferchichi M (2020) Probiotics – live biotherapeutics: a story of success, limitations, and future prospects – not only for humans. Probiotics and Antimicrobial Proteins 12, 1266–1289.
Probiotics – live biotherapeutics: a story of success, limitations, and future prospects – not only for humans.Crossref | GoogleScholarGoogle Scholar | 31376026PubMed |