Ruminants & Hindgut Fermenters

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Define ruminant in terms of digestion
Fermentation is the first mode of digestion
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Define hindgut fermenters in terms of digestion
Fermentation occurs in the enlarged caecum and colon
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What is the purpose of the reticular groove reflex?
It enables milk to bypass the rumen
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Why is preserving the reticular groove reflex of commercial interest?
It would enable food supplements or medicines to bypass the rumen
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Describe the reflex for the reticular groove
Milk in oral cavity/pharynx stimulates chemoreceptors. the vago-vagal reflex then goes to the medulla and then to the motor program where the groove closes and there is a pumping action of distal oesophagus
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What are the two types of carbohydrates?
Alpha bonded and beta bonded (no animal can digest this but bacteria can)
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How do anaerobic microbes digest beta bonded cellulose?
They hydrolyse the beta bonds by fermentation
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In a ruminant, what is cellulose broken down to?
It's broken down to glucose, then acetate, propionate and butyrate.
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What happens to the acetate?
Acetate is absorbed into the blood and is used in tissues as a triacylglycerol or as CO2 in muscle
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What happens to propionate?
Propionate is absorbed into the blood and is then used in tissues as glucose or as glycogen in the liver
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What happens to butyrate
Butyrate is either transported into the blood directly or is converted to ketone bodies. The products are then used in tissues as triacylglycerol or CO2 in muscles
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What factors influence fermentation?
Substrates (carbohydrates, lipids and proteins), microbes (substrate preferences and tolerance to conditions) and conditions (pH and substrate concentrations)
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In the fermentation of carbohydrate how come the products are acetic acid, propionic acid and butyric acid?
There is no oxidative phosphorylation and no oxygen
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Why is it important that the rumen is never empty?
When the rumen is full a dynamically stable complex network of inter-dependency with specific ratios of particular bacteria. If the rumen is empty this is disrupted.
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In normal animals which fatty acid is most abundant?
Acetate
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How does a high cereal diet control satiety and food intake?
Driven mainly by post-absorptive factors. VFA in blood (which is a sensory output from liver) turns off desire to eat
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How does a normal high roughage diet control satiety and food intake?
Driven mainly by pre-absorptive factors. When the rumen fills it turns off the desire to eat.
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What is rumen efficiency?
Rumen retention time of food
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What is the effect if you speed up the time the ruminant is being fed?
Food passes through the GIT faster
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What type of grass is better for digestion?
Early cut
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What is the function of saliva in ruminants?
Oral hygiene, food lubrication, primary source of pH buffer, replacement of fluids in rumen, anti-frothing proteins and wetting agents
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What salivary glands do ruminants have?
Parotid, sublingual and mandibular (zygomatic is only in carnivores)
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What types of glands are there?
Serous (parotid) and mixed (mandibular and sublingual)
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What controls salivary secretion?
CNS
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What controls the motility of the stomach in ruminants?
CNS
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Describe the anatomy of a salivary gland
It's like a grape. Acinus (grape), intercalating duct (stem) and striated duct (main stem)
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Where is saliva secretion derived from?
Plasma (blood flow is highly regulated)
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In monogastrics which part of the saliva gland alters the salt composition?
They are altered by duct cells
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Do ruminants alter their saliva's salt composition?
No
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How are the salivary glands controlled?
Parotid and sublingual nerve. The secretion is never zero and the main stimulus is food in mouth and the anticipation
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Describe the functions of salivation in ruminants
Buffering pH by secreting bicarbonate and phosphate (pH8). Supply of fluid and nutrients to sustain a microbial population (water can move along the osmotic gradient). Wetting and anti-frothing agents (protein content of saliva).
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How does a ruminant ensure food entering the rumen has a similar water content?
Saliva production remains constant but eating rate will vary depending on how dry (slow) or moist (fast) the food substance is.
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Other cards in this set

Card 2

Front

Define hindgut fermenters in terms of digestion

Back

Fermentation occurs in the enlarged caecum and colon

Card 3

Front

What is the purpose of the reticular groove reflex?

Back

Preview of the front of card 3

Card 4

Front

Why is preserving the reticular groove reflex of commercial interest?

Back

Preview of the front of card 4

Card 5

Front

Describe the reflex for the reticular groove

Back

Preview of the front of card 5
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