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Ruminants 2 (Rumen acidosis (Consumption of increased levels of hCHO, VFAs…
Ruminants 2
Rumen acidosis
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VFAs increased, pH greatly decreased
Proliferation of lactate producers at expense of lactate utilisers - lactate poorly absorbed cf VFAs
Too low pH injures rumen epithelium, water enters rumen by osmosis
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Development
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Micro-organisms for fermentation develop too, mostly from mother by licking
Still dependent on milk at this stage, milk goes via oesophageal groove
Oesophageal groove
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Reflex lost when weaned, retained in browsers (or if milk continually fed)
Protein metabolism
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Cellulolytic use NH4+, amylolytic use NH4+ & amino acids
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Micro-organisms
Most are bacteria
Amylolytic - Starch/hCHO --> Monosaccharides
- High tolerance of low pH
- Can proliferate quickly at expense of other microbes
Cellulolytic - Cellulose, hemi-cellulose, fructosans, pectin --> monosaccharides
Minor types
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Proteolytic - Protein :arrow_right: Peptides :arrow_right: Amino acids, used for microbial protein synth or fermented to VFAs + ammonium
Protozoa
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Produce VFAs, lactate, CO2 and H2
Ruminants can survive without, but make fermentation more efficient
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Methane production
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Glycolysis requires reduction of NAD+, CO2 reduced to CH4 via oxidation of NADH to regenerate NAD+, necessary
Carbohydrate metabolism
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VFAs produced by microbes, then absorbed by ruminants
Metabolism
Fermentation v. efficient (only 10% feed energy lost, mostly as CH4)
Rumen microbes can degrade many toxins before their absorption cf simple stomach animals - Foxglove leaves, ragwort
Fat metabolism
Unsaturated fatty acids, synth as stereoisomeric cis form in animal tissue
Rumen bacterial hydrogenation and generates some trans un-saturated fatty acids hence ruminant body fat differs to other species
Absorption
Rumen
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Lactic acid - tends to remain in lumen lowering pH, can be converted to glucose by liver
Ammonia - Ammonium predominates but ammonia rapidly absorbed so equilibrium shifted. Converted to urea by liver
Inorganic ions - Rumen is -ve to blood, hinds absorption of positive ions. (Na+/Mg2+ actively transported, Cl- in exchange for bicarb, Ca2+/PO4 2- mainly absorbed in SI)
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Metabolism of NPN
Ruminants can utilise NPN for protein synth, essential for healthy microbial population. Higher in silage than grass