Term
| What do protozoa do in the rumen? |
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Definition
| slow starch & protein fermentation |
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Term
| What do fungi do in the rumen? |
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Definition
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Term
| Rumen is (anaerobic/aerobic) |
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Definition
|
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Term
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Definition
-cellulase on surface of bacteria hydrolyze cellulose/hemicellulose/pectin into monosaccharides
-monosaccharides are absorbed into bacteria
-monos are broken down into 2 pyruvate, NADH, ATP, CO2 |
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Term
| What happens to the pyruvate that is produced when bacteria break down monosaccharides down? |
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Definition
| -fermentation to produce NADH/ATP/FADH2 and VFAs |
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Term
| What VFAs are produced during bacterial fermentation |
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Definition
Acetate
Butyrate
Propionate
Lactate (gets furhter broken down to acet/prop) |
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Term
| What % of a ruminant's energy comes from bacterial production of VFAs |
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Definition
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Term
| What effect does feeding a high-starch diet have on VFA production? |
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Definition
| increases the amount of propionate produced, decreases acetate |
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Term
True or False
There is a link between rumen pH and length of rumen papillae |
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Definition
true
low pH promotes growth of papilla, increasing surface area for VFA absorption |
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Term
True or False
VFAs are absorbed in the abomasum |
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Definition
false
everywhere but the abomasum |
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Term
| VFAs are absorbed via active/passive diffusion |
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Definition
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Term
| Why is the apical surface of papilla slighty more acidic? |
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Definition
-Na/H exchanger creates a slightly acidic environment
-this is required so that VFAs are dionized and can be easily absorbed |
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Term
True or False
VFAs must have a neutral charge in order to be absorbed |
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Definition
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Term
| How are VFAs metabolized after absorption |
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Definition
Acetate - used directly or to produce lipids
Propionate - converted to glucose
Butyrate - convered to ketone beta hydrxybutyric acid |
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Term
| What do valine, leucine and isoleucine all have in common |
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Definition
| They are branched chain amino acids which are converted into branched-chain VFAs |
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Term
Valine is converted into..
Leucine is converted into...
Isoleucine is converted into... |
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Definition
isobutyrate
isovalerate
methylbutyrate |
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Term
| What happens if a cow is fed lots of easily-fermentable starch? |
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Definition
-bacteria produce lots of VFAs, faster than they can be absorbed\
-rumen pH falls
-rumen flora changes, more lactic acid producing bacteria present
-pH falls further
-cow goes off feed, will only want forage
-may lead to bacteremia,septicemia etc |
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Term
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Definition
| bacterial enzyme that converts NPN to ammonia, which bacteria can absorb to produce AAs |
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Term
| Rumen pH should be acidic/neutral/basic |
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Definition
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Term
| What do primary rumen contractions do |
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Definition
|
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Term
| What do secondary rumen contractions do |
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Definition
| cause eructation to remove excess gases produced by fermentation |
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Term
| Why is ingesting large amounts of lush clover damaging to a cow? |
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Definition
| produces froth, which can prevent gas from stimulating the sensors in the cardia region of the stomach, so eructation doesn't occur |
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Term
| Rumination happens ___ minutes after feeding |
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Definition
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Term
| What nerve controls reticulorumen motility |
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Definition
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Term
| What causes abomasal impaction? |
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Definition
| Feeding poorly digestiible feed that has been mechanically broken down into smaller pieces, causes it to exit the rumen before it has been thoroughly fermented. Undigested fibers will end up in abomasum and cause impaction |
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Term
| Why are overwintering animals and pregnant animals more prone to abomasal compaction? |
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Definition
| increased energy demands in these conditions, so rumen motility will increase and food will exit the rumen before its fermented |
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Term
True or False
Water and feed particles exit the rumen at equal rates |
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Definition
|
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Term
True or False
Primary site of water absorption is the reticulorumen |
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Definition
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Term
| What stimulates the development of rumen papillae in calves? |
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Definition
|
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Term
| The reticular groove must be (open/closed) in order for milk to be diverted to the abomasum |
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Definition
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Term
| When might you see a closure of the reticular groove in adult cattle? |
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Definition
| dehydration, ADH released which stimulates thirst and closes the reticular groove, so H2O is directed to abomasum and can get to the SI quickly for absorption |
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Term
| What enzyme is secreted in the abomasum, which is not secreted in monogastric stomachs? What does it do? |
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Definition
lysozyme
-digests bacterial cell walls |
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Term
| How does nutrient absorption in the SI vary between monogastrics and ruminants? |
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Definition
| in ruminants, majority if nutrient absorption is in the ileum (not duodenum) |
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