Publikationsdatenbank

Selection, preparation and application of hostderived probiotic lactobacilli from chicken and their synergistic effects with phytobiotics on broilers (2020)

Art

Hochschulschrift

Autor

Ren, Hao (WE 4)

Quelle

Berlin, 2020 — 104 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/27660

Kontakt

Institut für Tierernährung

Königin-Luise-Str. 49
14195 Berlin
+49 30 838 52256
tierernaehrung@vetmed.fu-berlin.de

Abstract / Zusammenfassung

In Chapter 1, the general scientific rationale of the current thesis is introduced. In-feed antibiotics have benefited the animal husbandry for over 80 years, but antibiotic resistance emerged as a massive problem in recent decades. Antibiotics have been broadly used as growth promoters and for veterinary treatments in animal industry. This has contributed to a fast spread of antibiotic resistance, especially in poultry. Thus, it calls for theoretical and practical efforts to select promising alternatives to in-feed antibiotics. Several alternative feed additives have been comprehensively studied, among them probiotics and phytobiotics. However, the limitation in host-specificity of probiotics and their combination with phytobiotics in animal nutrition has restricted the in-depth understanding towards their functionality and role as AGP alternative. Thus, the refinements in probiotic screening, formulation and application is necessary and meaningful to better substitute AGP in animal production. In Chapter 2, a literature review regarding the research advances of in-feed probiotics and phytobiotics is provided. The literature review summarizes both probiotics and phytobiotics as AGP alternatives from the aspect of growth promotion, GIT microbiome alteration, immunoregulation, practical formulation and their respective combinations with other additives. The main objectives of the present thesis are to develop a rapid and efficient protocol of probiotic screening and preparation and investigate possible beneficial synergistic effects with phytobiotics. In Chapter 3, on basis of the given background, the aim of this study was to isolate and produce host-specific probiotics and to investigate the possible synergistic effects of these probiotics with commercial phytobiotics. This chapter also clarified the research objectives of the thesis including establishment of new screening method, in vitro characterization, optimization of production and stabilization and a proof-of-principle by an in vivo evaluation. The Chapters 4 to 6 comprehensively summarize investigations on the establishment of the novel screening method, production of probiotics and their effects of bacterial development in young broiler chickens. With the three-staged screening method, over 7000 isolates were filtered through the screening and finally two candidates were selected for their excellent in vitro and ex vivo activity against ESBL E. coli. The strain-specific production parameters of two probiotic strains were optimized regarding cultivation and formulation, achieving both relative high yields and high stability after production. The chosen probiotic strains and two commercial phytobiotics as well as their combinations were tested in a proof-of-principle feeding trial. The composition and activity of crop and caecum microbiota of young broilers were analyzed to demonstrate the impact of the feed additives on the host intestinal ecology. Additionally, the ability to inhibit colonization of ESBL producing E. coli as well as C. perfringens in either foregut or hindgut of birds was documented. These three consecutive studies showed an overarching process from isolation of probiotic strains to functional feed additives in a feeding trial. In Chapter 7, the results from the current thesis are discussed in general. The efficiency of the three-staged method was emphasized by discussing handling and financial cost during the screening step. The method also allows an easier enlargement of the screening scale compared to traditional one-step screening procedures. It also endows the feasibility to drastically enlarge the screening scale compared to traditional one-step screening methods. With both experimental and computational means, the formulation of selected probiotic strains into feed additives was improved. Finally, the prepared probiotic feed additives were shown to exert beneficial effects on the gut microbiota of young broilers. This was especially observed for a specific combination of probiotic and phytobiotic. This evidenced the great potential of probiotics in combination with phytobiotics as an alternative to the use of AGP in broiler husbandry.