Host-Microbe Interactions: Effects on nutrition and physiology - Dr. Tom Burkey, University of Nebraska-Lincoln, from the 2014 Allen D. Leman Swine Conference, September 15-16, 2014, St. Paul, Minnesota, USA. More presentations at http://www.swinecast.com/2014-leman-swine-conference-material

1. Host-Microbe Interactions:
Effects on nutrition and
physiology
Thomas E. Burkey
September 15, 2014
Allen D. Leman Swine Conference

2. Outline
 Introduction
 Microbial Diversity in the Gut
 Function of the gut microbiota
 Composition of gut microbiota is affected by diet
 “Gut Health” Defined
 Does health status affect gut microbial community
composition and function?
 Future Directions

3. Microbial Diversity in the Gut
• The adult human gastrointestinal (GI) tract contains
all three domains of life—bacteria, archaea, and
eukaryota.
• Human gut microbiota:
• 100 trillion archaeal and bacterial cells
• Distributed over 1000 species
• Dominated by bacterial species
• The most dominant divisions are the Firmicutes,
Bacteroidetes, Actinobacteria and Proteobacteria.
Tremaroli & Backhed. Nature: 489, 242–249

4. Overview of microbial diversity
of the human gut
Bäckhed et al., 2005

5. Host specific gut microbiota composition
Dethlefsen et al., 2007

6. Function of the gut microbiota
 Microbiota: collective microbial community inhabiting a
specific environment
 Microbiome: collective genomic content of a microbiota
(i.e., total genetic capacity of the community)
 Metagenome: total DNA that can be extracted from an
environment (i.e., aggregate of host DNA and
microbiota DNA)
 Host bacteria, archaea, fungi, and yeasts convert
nutrients and host-derived substrates into various
metabolites
 Dynamic yet stable
 Microbiota composition differs in health and disease

7. Gut microbiota: protein metabolism
 Dietary and host-derived
(pancreatic juice, mucus,
shed epithelial cells)
protein is available for
microbial fermentation.
 Products included
beneficial SCFAs and
potentially toxic
metabolites (e.g.,
ammonia, phenolic
compounds, sulphides)
Vavassori et al. 2009. J. Immunol. 183: 6251.

8. Gut microbiota: carbohydrate metabolism
 Principle products
of fermentation:
 Gases
 SCFAs
 Butyrate
 Propionate
 Acetate
Vavassori et al. 2009. J. Immunol. 183: 6251.

9. Gut microbiota: lipid metabolism
 No evidence that ingested lipids are degraded by
microbiota
 However, dietary lipid is linked to bile acid secretion
 Bile acids can be transformed into bio-active
metabolites by gut bacteria
 Key players in primary bile acid deconjugation are
Bifidobacterium sp. and Lactobacillus sp.
 Bile acid metabolites are ligands for nuclear
hormone receptors (e.g., farnesoid X receptor; FXr)
 FXr signaling affects many gene targets
 Bile acid synthesis/transport; lipid and
carbohydrate metabolism, regulation of intestinal
innate immunity
Vavassori et al. 2009. J. Immunol. 183: 6251.

10. Composition of gut microbiota is
affected by diet
 Enterotype 1, enriched in Bacteroides: associated with diets rich in animal
fat/protein
 Enterotype 2, enriched in Prevotella: associated with diets rich in
carbohydrates
 Enterotype 3, enriched in Ruminococcus: not well defined
Arumugam et al., 2011Nature: 473, 174–180

11. Human Example: Impact of diet
in shaping gut microbiota
 Comparison of fecal microbiota
of European children and
children from rural Africa
Proc Natl Acad Sci U S A. 2010 Aug 17;107(33):14691-6

12. Nutrient x Health Interactions: Models to
explore the effects of gut microbes on porcine
health and growth performance
 Effect of dam parity on litter performance,
transfer of passive immunity, and progeny
microbial ecology (Carney-Hinkle et al., 2013)
 Effects of diet on growth performance and gut
health in healthy pigs
 DDGS (Tran et al., 2011)
 Lactose and yeast-dried milk (Tran et al., 2012)
 Chicory (inulin) (Mastromano et al., 2014)
 Spray-dried porcine plasma (Tran et al., 2014)
 Effects of diet on growth performance and gut
health in sick pigs
 PRRSV
 PCV2

13. Effect of corn distillers dried grains with
solubles on growth performance and health
status indicators in weanling pigs (Tran et al., 2012)
 Pigs fed DDGS may have increased microbial similarity and decreased
bacterial diversity, as well as reductions in microbial richness

14. Effects of lactose and yeast-dried milk on growth
performance, fecal microbiota, and immune parameters
of nursery pigs (Tran et al., 2012)
 The effects of lactose and yeast-dried milk on Lactobacillus
composition at d 0, 7, and 14 postweaning
 At weaning (d 0), no differences among treatments for fecal
Lactobacillus staining intensity.
 At d 7 postweaning, pigs fed lactose with or without yeast-dried milk
had greater (P < 0.05) staining intensity of putative L. johnsonii when
compared with the control pigs.
 At d 14 postweaning, control pigs had greater putative L. delbrueckii (P
< 0.04) and tended to have greater L. sobrius/amylovorus (P = 0.10).

15. Microbial transmission and assembly of gut microbiota in
neonatal pigs on d 7 and 14 postfarrowing.
Hinkle et al. 2011. J. Anim. Sci. 89(E-Suppl. 2): 662. (Abstr.)

16. Differences in core microbiota between P1 and
P3 dams and their progeny.
Hinkle, E.E. et al. 2012. Proc. 12th Int. Symp. Dig. Phys. Pigs. Keystone, CO.

17. Effects of spray-dried porcine plasma on
fecal microbiota in nursery pigs
 Ion Torrent profiling
sequences target
gene based on pH
fluctuation during
nucleotide chain
synthesis
 Relative abundance
of major phyla (A),
families (B), and
genera (C) in pigs
fed control and
SDPP diets across
a 4-wk feeding
period.

18. Effects of spray-dried porcine plasma on
fecal microbiota in nursery pigs
 Feeding SDPP alters
fecal microbial
communities in pigs
 May decrease pathogenic
bacteria (e.g., C. difficile, E.
rhusiopathiae, B.
helcogenes)
 May increase cellulose
degrading bacteria (e.g.,
Clostridium sp. and
Ruminococcus sp.)
 May increase butyric acid-producers
(e.g.,
Lactobacillus sp. and
Megasphaera elsdenii)
Distribution of shared OTUs in pigs fed spray-dried
porcine plasma compared to control pigs.

19. “Gut Health” Defined
 Linking diet, gut enterotypes, and health??
 …”a state of physical and mental well-being in the
absence of GI complaints that require the
consultation of a doctor, in the absence of
indications of or risks for bowel disease and in the
absence of confirmed bowel disease”.
 Five major criteria for a healthy gut
 Effective digestion/absorption
 Absence of GI illness
 Normal and stable intestinal microbiota
 Effective immune status
 Status of well-being
Bischoff, S.C. 2011. ‘Gut Health’: a new objective in medicine? BMC Medicine. 9:24.

20. “Gut Health”: Underlying Mechanisms
Bischoff, S.C. 2011. ‘Gut Health’: a new objective in medicine? BMC Medicine. 9:24.

21. Functional entities to maintain
Gut Health
GI Microbiome
 Energy homeostasis
 Mucosal infection
 Mitigates immune hypersensitivity
 Contributes to maintain GI barrier
GI Barrier
 Epithelial defense
 Metabolic function
 Mucosal immune system
 Enteric nervous system

22. Microbial markers of dysbiosis
Rajilić-Stojanović, 2013

23. Does health status affect gut
microbial community composition
and function? ……….PRRSV model
 The impact of PPRSv on feed efficiency, digestibility
and tissue accretion in grow-finisher pigs
 Objective: Characterize the impact PRRSv challenge
has on
 Feed efficiency, energy and nutrient digestibility
 Body composition and tissue accretion
 Post-absorptive metabolism
 Hypothesis: The reduction in growth rates during
PRRSv infection is associated with reduced energy
and nutrient digestibility

25. Impact of PRRSv on body composition
and tissue accretion
 DXA predicts total mass, lean, fat, and
bone mineral density/content

26. Effects of PRRSv challenge on Apparent
Total Tract Digestibility (ATTD)
 21 dpi
 65 dpi
How do you explain the long term negative impact on ATTD?

27. What is the metabolic cost of disease
challenge?
 Energy
 Immune response
 Nitrogen clearance
 Changes in metabolic rates
 Amino Acids
 Synthesis of immune cells
 Gluconeogenesis
 Metabolic Shift?
 Up-regulation of glycolysis
 Amino acids: immune proteins, gluconeogenic
intermediates

28. Metabolic Shift?
 Poorer growth
responding pigs to
PRRSv
 Higher blood glycerol,
urea, and lactate
 Lower blood glucose,
pyruvate and citrate
 Pigs that regulate
metabolic shifts
(oxidative to glycolytic
metabolism) may
handle immune
challenges better?
 This appears to be
also influenced by
genetic selection for
disease tolerance
How do you explain the long term negative impact on ATTD?
 Changes in gut microbial community, metabolites???

29. Does health status affect gut
microbial community composition
and function? …….PCV2 model
 The effects of PCV2 on growth performance of pigs
fed simple vs. complex diets
 Objective: Characterize the effects of simple vs
complex diets on pigs challenged with PCV2
 Hypothesis: Diet complexity will have differential
effects on growth performance of pigs challenged
with PCV2
 96 barrows; 33 d of age; 7.1 kg initial BW
 PCV2 status (vaccinated v infected)
 Diet type (complex, simple, simple + probiotic)

30. The effect of PCV2 on BW, kg
Overall PPCV = 0.061

31. The effect of diet type on ADG, kg

32. The effect of diet type on ADFI, kg

33. Effect of PCV-status and diet type on
digestibility…..
gut microbial community…..

34. Areas of opportunity
 Five major criteria for a healthy gut
 Effective digestion/absorption
 Absence of GI illness
 Normal and stable intestinal microbiota
 Effective immune status
 Status of well-being
Can we quantify to further define “Healthy Gut”?

35. Areas of opportunity
 Understanding how the diet affects the microbiome
and how the metagenome is affected by diet in both
healthy and sick pigs…….
 Reduced feed intake/digestibility
 Reduced tissue accretion
 Long lasting impact on feed efficiency
 Glycolytic shift may be important
 Altered nutrient requirements?
 Increasing appetite
 Lowering energetic cost of disease
 Potential dietary interventions

36. Areas of opportunity
 Development of pre- and probiotics?
Synbiotics?
 Lactobacillus reuteri competition
experiment

37. Areas of opportunity
 Development of a cecum cannulated pig
model to evaluate gut microbial
community dynamics and function at the
molecular and physiological levels
 Gut Microbial triggers that influence
the disease associated phenotype
 Can microbial gene expression be
evaluated to understand microbial
function?
 Allows for repeated real-time
monitoring of the gut microbiome

38. Acknowledgments
 USDA – Animal Health Formula Funds
 National Pork Board
 Grant# 12-163
 Iowa Pork Producers Association
 Grant# 12-113
 Choice Genetics
 International Ingredient Corporation
 Drs. Gabler, and Odle, laboratory staff and students
 Drs. Miller, Fernando, Walter, and Hostetler, laboratory staff
and students