The Dynamics of the Digestive System Digestive Physiology and the Role of Microorganisms

1. JKS Poultry Health Research Laboratory The Dynamics of the Digestive SystemDigestive Physiology and the Role of Microorganisms Guillermo Tellez, Akrum Hamdy and B. M. Hargis1

2. Gut: The Inner Tube of Life • Our gut is huge—as long as a bus and if flattened out, sufficient to cover a football field. • It is home to an almost inconceivable number of microorganisms. • It is continuously assaulted by extraordinary volumes of foodstuffs, noxious chemicals, and potentially harmful bacteria. • It oversees a remarkably efficient salvage operation, extracting essential nutrients from an intermittently flowing river of food and water.

3. The Inner Tube of Life • Energy homeostasis. • Immune integrity • And the movement of its contents mean that the gut has to be in continuous dialogue with the rest of the body. • It is our powerhouse and has even been called our second brain.

4. The Gut: Inside Out • The developing gut faces unique challenges as one of the longest and largest organs in the body and also because it is constantly interfacing with external factors through the diet.

5. The Gut: Inside Out • At first glance, the gut looks deceptively simple: • An epithelial tube composed of a few cell types and surrounded by an innervated muscle layer

6. Tales from the Crypt • The gut is consisting of a single delicate layer of epithelial cells that are continuously replaced at a rate of ~70 billion per day. • This epithelium serves a multiplicity of functions: absorbing nutrients and water, secreting mucus, and exporting a broad array of enzymes, hormones, and antimicrobial compounds.

7. The Gut: Inside Out • Yet in evolutionary terms, the gut, as an endodermal organ, predates any mesodermal organ, and it has reached a level of complexity and sophistication that is only starting to be appreciated.

8. The Intestinal Microflora • Is an essential ‘‘organ’’ in providing nourishment, regulating epithelial development, and instructing innate immunity • Yet, surprisingly, basic features remain poorly described.

9. Host-Bacterial Mutualism • New studies are revealing how the gut microbiota has co-evolved with us and how it manipulates and complements our biology in ways that are mutually beneficial.

10. Thus, it seems appropriate to view ourselves as a composite of many species • And our genetic landscape as an amalgam of genes embedded in our Homo sapiens genome and in the genomes of our affiliated microbial partners (the “microbiome”).

11. The Gut Microflora • Is as individual as our personalities and contains a diverse ensemble of representatives from all three branches of life on Earth: • Bacteria • Archaea • Eukarya

12. There are at least 800 species of bacteria, most of which are completely mysterious. • This means that the genome buried inside of our gut—the “microbiome”—may harbor 100 times more genes than our own genome, and it endows us with traits that, thankfully, we have not had to evolve on our own.

13. The Gut Microflora • The size of the population—up to 100 trillion. • Bacteria living in the gut achieve the highest cell densities recorded for any ecosystem. • And is 10 times greater than the total number of our somatic and germ cells.

14. It is composed of different cell lineages with a capacity to communicate with one another and the host. It consumes, stores, and redistributes energy. It mediates physiologically important chemical transformations. And it can maintain and repair itself through self-replication. Gut microflora can be pictured as an “organ” placed within a host organ:

15. There is a tendency to regard all microorganisms as harmful • Nothing could be further from the truth. • The number of non pathogenic species far exceeds the number of pathogenic species • And many of the known bacteria are in fact useful, even essential for the continued existence of life on earth.

16. Through out millions of years of evolution • Animals have developed the means for supporting complex and dynamic consortia of microorganisms during their life cycle.

17. The Perfect Symbiosis Beneficial bacterial live in healthy, helpful, and cooperative symbiosis with their hosts. The level of health depends on a large number of conditions established by the intestinal microflora

18. The early establishment of the intestinal microbiota promotes: • Assembly of the gut-associated lymphoid tissue • Educate the immune system • Affects the integrity of the intestinal mucosal barrier • Proliferation and differentiation of its epithelial lineages • Regulates angiogenesis • Modifies the activity of the enteric nervous system • Extracting and processing nutrients in the diet

19. Metabolic Machines • The microflora can metabolize proteins and protein degradation products • Sulfur-containing compounds • Endogenous and exogenous glycoproteins • FOS, the most abundant source of carbon on earth

20. Changing Physiology • Some organisms grow on intermediate products of fermentation such as, lactate, succinate, formate, and ethanol and convert these to end products including SCFA • A process which has a direct impact on digestive physiology.

21. Early Probiotic Work • Clearly demonstrated that early neonatal colonization with normal microflora improved resistance to bacterial pathogens [71,72,73] • Increase productivity of the animals [74,75]

22. Beneficial Bacteria Probiotics Prebiotics Synbiotics Short Chain Fatty Acids

23. SCFA Tremendous Biologic Activity • Energy source for enterocites [28,30] • Increasing blood flow [31] • Regulating intestinal motility [32, 33] • Increasing epithelial cell prolipheration [34] • Decreasing pH [35] • Mucin Production [36]

24. Low pH Ca +Acetate Ca +Propionato In rats, ceca is the most important site of Ca+ absorption[29] In humans, large quantities of Ca+ are absorbed in the colo-rectal region[30] BUTIRATE

25. Up-regulation of gene expression for digestive hormones PROPIONATE

26. Probiotics and Health • The use of lactic acid bacteria as feed supplements goes back to pre-Christian times when fermented milks were consumed by humans.

27. Nobel prize for Physiology 1908, was awarded to Elie Metchnikoff“In recognition of his work on immunity" • But his accurate description of vital elements in the body's intestinal flora is equally notable. • He developed and prescribed to his patients bacteriotherapy, i.e. the use of lactic acid bacteria in dietary regimens.

28. Metchnikoff cited the observation that Bulgarian peasants consumed large quantities of soured milk and also lived long lives. • He isolated what he called the 'Bulgarian bacillus' from soured milk and used this in subsequent trials. • This organism was probably what became known as Lactobacillus bulgaricus and is now called L. delbrueckii subsp bulgaricus.

29. Probiotic • Is defined as a live microbial food supplement which benefits the host by improving its intestinal microbial balance.

30. Beneficial Bacteria of Probiotics may improve metabolism by increasing: • Absorptive capacity [56] • Protein and energy metabolism [57, 58] • Fiber digestion [58] • Energy conversion [59] • Gut maturation [60] • Immunostimulation [55]

31. Prebiotic • However, probiotics can only be effective if the requirements for their growth are present in the GIT. • The concept of prebiotics is relatively new; it developed in response to the notion that nondigestible food ingredients (e.g. nondigestible oligosaccharides) are selectively fermented by one or more bacteria known to have positive effects on gut physiology.

32. Synbiotic • The bacterial nutrient package will not be advantageous without the presence of the targeted, beneficial bacteria. • Likewise the live microbial product will not succeed if the environment into which it is introduced is unfavorable [64].

33. Role of Microorganisms in Poultry Production • In poultry, intestinal villi, which play a crucial role in digestion and absorption of nutrients, are underdeveloped at hatch [65] but maximum absorption capacity is attained by 10 days of age [66].

34. In the immediate post hatch period • Birds must undergo the transition from energy supplied by the endogenous nutrients of the yolk to exogenous carbohydrate-rich feed. • During that critical time dramatic changes occur both in the intestinal size and morphology [65].

35. Manipulation of Intestinal Microflora Antibiotics Diet Probiotics Prebiotics Synbiotics

36. Probiotics and Prebiotics as an Alternative to Antibiotics for Control of Bacterial Pathogens in Poultry • Bacterial antimicrobial resistance in both the medical and agricultural fields has become a serious problem worldwide [70]. • Antibiotic resistant strains of bacteria are an increasing threat to animal and human health, with resistance mechanisms having been identified and described for all known antimicrobials currently available for clinical use [70].

37. Social pressures have led to the creation of regulations to restrict antibiotic use in poultry and livestock production. • There is currently increased public and scientific interest regarding the administration of therapeutic and sub-therapeutic antimicrobials to animals

38. There is a need to evaluate potential antibiotic alternatives to improve disease resistance in high intensity food animal production. • Improving the disease resistance of animals grown without antibiotics will not only benefit the animals’ health, welfare, and production efficiency but is also a key strategy in the effort to improve the microbiological safety of poultry products [70].

39. Enteric Health Research Team • B. M. Hargis, D.V.M.,Ph.D. • G.Tellez, D.V.M., Ph.D. • A. M. Donoghue, Ph.D. • D.J. Donoghue, Ph.D. • M. Farnell, Ph.D. • L. R. Bielke, Ph.D. Student • V. Salvador, Ph.D. Student • A. Torres, Ph.D. Student • S.E. Higgins, Ph.D. Student • J. Higgins, Ph.D. Student • F. Solis, Ph.D. Student • S. Henderson, M.S. Student • C.M. Pixley, M.S. Student • A. Wolfenden, M.S. Student • Akrum M. M. Hamdy

40. During the last four years • Our laboratory has worked toward the identification of probiotic candidates for poultry which can actually displace Salmonella and other enteric pathogens which have colonized the gastrointestinal tract of chicks and poults.

41. Bielke et al., 2004Poultry Sci. 82: 1378-1382. • Published studies indicated that after screening more than 8 million enteric organisms for competition in vitro, 36 organisms were identified that had the ability to exclude Salmonella in neonatal poultry.

42. Floramax: Manufactured Under Exclusive License fromThe University of Arkansas • Further screening allowed the identification of 11 LAB (of the genus or related to Lactobacillus in the product FM-B11TM (Floramax) that were even more efficacious in the treatment of Salmonella infected chickens and poults.

43. Vicente J. L. et al., 2005 Avian Diseases Submitted Salmonella Recovery • In laboratory challenge studies, 75-85% reductions in Salmonella recovery rates from challenged chicks treated with FM-B11TM probiotic culture. * * * * * Significantly (p<0.05) lower

44. Vicente J.L. et al., 2005 JAPR Submitted • By selecting Salmonella infected flocks pre-slaughter, we have demonstrated that treating such flocks, approximately two weeks prior to slaughter, with FM-B11TM can markedly reduce environmental Salmonella recovery in commercial turkeys and broilers.

45. S. E. Higgins et al., 2005 J. of Applied Poultry Research 14:345-348 • In recent studies, treatment of idiopathic enteritis in commercial poults with FM-B11TM also compared favorably to selected antibiotic therapy Mean Weight, Day 21 Control Prob.1 Prob. 2 Antibiotics

46. Torres-Rodriguez A. et al. 2005British Poultry Science Submitted. • Large scale commercial trials have indicated that appropriate administration of FM-B11TM to turkeys increased body weight gain at processing by approximately 190 g with over 120 flocks evaluated

47. Torres-Rodriguez A. et al. 2005Poultry Science Submitted • Administration of FM-B11TM and dietary lactose at a very low concentration [0.1%] greatly enhanced the growth rates of turkeys under commercial conditions and furthered reduced total production costs

48. Probiotics as an Alternative to Antibiotics for Control of Bacterial Pathogensand Improve Productivity in Poultry • These data indicate that selection of therapeutically efficacious probiotic cultures with marked performance benefits in poultry is possible, and that defined cultures can sometimes provide an attractive alternative to conventional antimicrobial therapy.

49. Diversity of the Intestinal Microbial Flora • The endogenous GI microflora plays a fundamentally important role in health and disease, yet this ecosystem remains incompletely characterized and its diversity poorly defined

50. Conclusions • The interest in digestive physiology and the role of microorganisms has generated data whereby human and animal well being can be enhanced and the risk of disease reduced.