Gastrointestinal Physiology Part 9 PDF

Physiology II – Gastrointestinal Physiology Part 9 Fermentative Digestion of Sarah Hooper, DVM, MS, PhD E-mail: [email protected] 9  Learning Objectives Define fermentative digestion and rumination...

Physiology II – Gastrointestinal Physiology Part 9 Fermentative Digestion of Sarah Hooper, DVM, MS, PhD E-mail: [email protected] 9  Learning Objectives Define fermentative digestion and rumination Describe the different forestomach compartments of the ruminant animal List relevant ruminal microorganisms and classify them Describe the ruminal environment List the ruminal content and layers Describe the fate of carbohydrates in the ruminant Describe volatile fatty acids (VFA) synthesis in the rumen and uses in the host animal 2 3/4/2024 Fermentative Digestion Physiology  Ruminant Stomach Ruminants: a diverse group of mammals that regurgitate and re-masticate their food Two suborders: Ruminantia (deer, elk, reindeer, antelope, giraffe, bison, cow, sheep, goat) Tylopoda (camel, llama, alpaca, vicuña) Ruminants are very successful herbivores and can adapt to multiple environments From: Hofmann R.R. Oecologie 1989 3 3/4/2024 Fermentative Digestion Physiology  Ruminant Stomach 4 3/4/2024 Fermentative Digestion Physiology  Ruminant Stomach Fermentative digestion occurs in specialized compartments localized before the stomach (forestomach in ruminants) or after the stomach and small intestine (cecum and colon in horses) The microbes responsible for fermentative digestion include bacteria, fungi, and protozoa In contrast to monogastric animals, enzymes for digestion are of microbial origin (not produced by the host - mostly) Fermentation requires appropriate secretions, motility, and temperature conditions in the forestomach's Associated with fermentative digestion are regurgitation and re-mastication of food to provide more finely divided material and thereby a greater surface area for microbial digestion 6 3/4/2024 Fermentative Digestion Physiology  Ruminant Stomach Cranial sac Dorsal sac Caudodorsal blind sac Reticular groove Caudoventral Reticulo-omasal blind sac orifice Rumino-reticular Ventral sac fold Pillars of rumen From: Sjaastad, Sand, Hove. Physiology of Domestic Animals 2013 The rumen occupies a prominent portion of the viscera on the left side of the animal (the reticulum is close to the heart!) 7 3/4/2024 Fermentative Digestion Physiology 8 3/4/2024 Fermentative Digestion Physiology  Ruminant Forestomachs The forestomachs are lined with stratified squamous epithelium From: Sjaastad, Sand, Hove. Physiology of Domestic Animals 2013 9 3/4/2024 Fermentative Digestion Physiology  Ruminant Stomach From: Sjaastad, Sand, Hove. Physiology of Domestic Animals 2013 A) Normal topography of left abdominal viscera, cow. B) Left The abomasum, the true stomach, displacement of abomasum. Illustration by Dr. Gheorghe is mostly on the right side of the Constantinescu. Adapted, with permission, from DeLahunta and Habel, Applied Veterinary Anatomy, W.B. Saunders, 1986. animal 10 3/4/2024 Fermentative Digestion Physiology https://www.merckvetmanual.com/digestive-system/diseases-of-the-abomasum/left-or-right-displaced-abomasum-and-abomasal-volvulus?sf59745859=1  Rumen Development The abomasum is the largest compartment of the newborn‘s stomach Enlargement of the forestomach occurs rapidly after birth but the rate depends on diet type (solid feeds & concentrate accelerate development) and contact with adult ruminants (inoculation of microorganisms) Non-ruminant period: from birth to 3 weeks Transitional period: 3 to 8 weeks From: Sjaastad, Sand, Hove. Physiology of Domestic Animals 2013 11 3/4/2024 Fermentative Digestion Physiology  Ruminal Environment Substrate availability: food intake (time spent ruminating) regulated by volume, structure, energy, palatability Temperature: about 0.5 to 1 degree Celsius above the body temp. Fluids: drinking water and saliva (volume of daily saliva produced depends directly on chewing time) pH: 5.5 -7 (acid synthesis and acid reabsorption, buffer substances coming from the saliva and rumen epithelium) 12 3/4/2024 Fermentative Digestion Physiology  Ruminant Microbiome Grouping of rumen bacterial species according to type of substrates fermented 2 Diet composition directly influences the rumen microbiome structure (Data obtained from: Kim et al. 2011; Jami and Mizrahi 2012; Petri et al. 2013; Jami et al. 2013; Jami et al. 2014; Sirohi et al. 2012; Lima et al. 2014; McCann et al. 2014; Kumar et al. 2015; Weimer 2015; Henderson et al. 2015), which affects microbial functions and consequently biomass degradation, resulting in the release of methane (CH 4 ) and carbon dioxide (CO 2 ) via eructation and From: Klein. Cunningham‘s Textbook of Veterinary Physiology 2012 volatile fatty acids that are absorbed by the epithelium J.L. de Azevedo, M.C. Quecine (eds.), Diversity and Bene ts of Microorganisms 13 3/4/2024 Fermentative Digestion Physiology from the Tropics, DOI 10.1007/978-3-319-55804-2_16  Microbiome and Physiology Multi-omics reveals that the rumen microbiome and its metabolome together with the host metabolome contribute to individualized dairy cow performance https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-020-00819-8 A short note on the Gut-Brain access: https://psychscenehub.com/psychinsights/the- simplified-guide-to-the-gut-brain-axis/ And if you need a new game to share with your family/roommates/friends : The Microbiome Game https://microbe.net/gutcheck/download-the-game/ 14 3/4/2024 Fermentative Digestion Physiology  Ruminant Stomach JG 2014 Most protozoa are ciliated and belong to the genus Isotricha or Entodinium Grouping of rumen protozoa according to their morphology and size Size (20 – 200 um) - big - medium From: Duke‘s Physiology of - small Domestic Animals Systematically - Flagelates (few species) - Ciliates (more numerous) 15 3/4/2024 Fermentative Digestion Physiology From: Ogimoto and Imai. Atlas of Rumen Microbiology 1981  Ruminant Stomach Ruminal ecosystem Protozoa ingest large numbers of bacteria and hold bacterial number in check Protozoa may also play a role on starch and protein digestion they prolong the digestion of these substances (ingest them and protect them from bacterial action) Symbiosis The waste products produced by one species serve as substrate for another R. albus digests cellulose but cannot digest protein; B. ruminicola digests protein but cannot digest cellulose, then cellulose digestion by R. albus provides hexoses for the energy needs of B. ruminicola, and protein digestion by B. ruminicola provides ammonia and fatty acids for the growth of R. albus 17 3/4/2024 Fermentative Digestion Physiology  Substrates and Products of Fermentative Digestion Ruminal content and layers From: Sjaastad, Sand, Hove. Physiology of Domestic Animals 2013 18 3/4/2024 Fermentative Digestion Physiology  Fate of carbohydrates, proteins, and lipids in the ruminant Generation and fate of VFA in the ruminant Carbohydrates Proteins Lipids Rumen microbes VFA Acetate Propionate Acetate Butyrate Liver All tissues Adipose tissues Glucose Energy Fatty acids 19 3/4/2024 Fermentative Digestion Physiology  Fate of carbohydrates, proteins, and lipids in the ruminant Chemical structures of the major volatile fatty acids (VFAs) produced by fermentative digestion 20 3/4/2024 Fermentative Digestion Physiology From: Klein. Cunningham‘s Textbook of Veterinary Physiology 2012  Fate of carbohydrates, proteins, and lipids in the ruminant The cell wall of plants (leaves and stems) has a large portion of carbohydrates which are important for stability and rigidity of the growing plant (structure carbohydrates) Plant cell walls are important substrates for fermentative digestion (and significant nutrient sources of many microorganism species) 21 3/4/2024 Fermentative Digestion Physiology  Fate of carbohydrates, proteins, and lipids in the ruminant content Wagon Carbohydrates: cellulose, hemicellulose, pectin Cellulose, hemicellulose and pectin will be hydrolyzed by the enzyme cellulase. After hydrolysis, monosaccharides are released from the polysaccharide. These monosaccharides are NOT available for absorption by the animal; they are further metabolized by the microbes Lignin (not a carbohydrate) is, in contrast, essentialy indigestible (although some fungi can digest lignin) It increases with the age of a plant and ambiental temperature 22 3/4/2024 Fermentative Digestion Physiology  Fate of carbohydrates, proteins, and lipids in the ruminant Essentially all dietary proteins and carbohydrates are subjected to fermentative digestion in the forestomachs Maj Products are glucose, other monosacch. and short chain polysaccharides that are released into the fluid phase Eies These glucose and other sugars do not become available to the host animal; they are absorbed into the cell bodies of microbes 23 3/4/2024 Fermentative Digestion Physiology  Fate of carbohydrates, proteins, and lipids in the ruminant Within the microbial cell, glucose enters the glycolytic pathway......to produce 2 pyruvate from one glucose molecule (plus 2 NADH and 2 ATPs which is used by the microbes) Fermentative digestion is anaerobic and the products are volatile fatty acids (VFA, aka short chain fatty acids SCFA) 24 3/4/2024 Fermentative Digestion Physiology  Aerobic and Anaerobic Conditions – Pyruvate still formed QI Pyruvate metabolism in aerobic and anaerobic bacteria. Under aerobic conditions, bacteria utilize pyruvate dehydrogenase to convert pyruvate into acetyl-CoA and carbon dioxide. Anaerobic bacteria can only grow under reduced oxygen concentrations and use pyruvate: ferredoxin oxidoreductase to convert pyruvate into acetyl-CoA and carbon dioxide. Amixicile, a novel strategy for targeting oral anaerobic pathogens - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Pyruvate-metabolism-in-aerobic-and-anaerobic-bacteria- 25 3/4/2024 Under-aerobic-conditions-bacteria_fig1_319491617 [accessed 15 Nov, 2021]  Substrates and Products of Fermentative Digestion ATP 4 3 4 3 Red. Cofactors 4 2 0 0 NADH/FADH2 O2 0 0 1 0 26 3/4/2024 Fermentative Digestion Physiology  Substrates and Products of Fermentative Digestion The primary volatile fatty acids (VFA) are acetic acid (acetate), propionic acid (propionate), and butyric acid (butyrate) If Pathways of volatile acid (VFA) production by the rumen From: Sjaastad, Sand, Hove. Physiology of Domestic Animals 2013 ATP 4 3 4 3 MoveaTPs Red. Cofactors 4 2 0 0 NADH/FADH2 O2 0 0 1 0 27 3/4/2024 Fermentative Digestion Physiology  Go 28 3/4/2024 Add a footer  o 29 3/4/2024 Add a footer 30 3/4/2024 Add a footer  f opt 5.5.70 invone Itar Odgers Goes Interdict wigud E Adaptive whale 31 3/4/2024 Add a footer  quartanson 32 3/4/2024 Add a footer