Lecture 5 Flashcards
WHat does processing (chopping, grinding) of feed do to the pH of the rumen and why?
Decreases pH
Reduces chewing, increases saliva production
Increases fermentation rate by increasing surface area
3 affects of abnormal pH
Low pH decreases motility
Effects which microbes will grow or not grow
Decreases feed intake
What does saliva contains that helps with pH of rumen?
Lots of HCO3-
Phosphate buffers
How does rumen maintain an almost neutral pH?
- Saliva
- Carbonic anhydrase in rumen epithelial cells
- Donates H to acid anion, absorbing acid from rumen to blood
- HCO3- left in rumen as buffer - Can add NaHCO3 to diet as a buffer
3 glands involved in saliva producion
Minor glands - mucus
Parotid Gland - Serous
Submandibular Gland - Mixed
What can occur to a ruminant with grain overload other than acidosis?
Rumen becomes hypertonic
H2O pulled in to rumen
Systemic Dehydration
What produces CO2 in the rumen?
Decarboxylation
Carbonic Anydrase
What gasses are found in the rumen?
CO2 - 65%
CH4 - 25%
N2 - 7%
O2 - 0.5%
H2 - 0.2%
H2S - 0.01%
One way to reduce methane production?
Feed Ionophores
- H2 converted to propionate, not methane
Define Rumen Turnover
Amount of time required to replace the rumen contents with an equivalent volume
How do different feedstuffs affect rumen turnover?
Roughage diets - more rapid (3-7 times/day)
Grain Diets - slower (2-3 times/day)
What has the greatest influence on Rumen Turnover?
Salivation
Water Intake
What is solid turnover?
Rate of loss of solid material from the rumen
What determines solid turnover?
- Digestibility of feed
- Grain digestibility = 90%
- Forage digestibily = 50% - Amount of feed
more feed = rumen distention = more motility
More motility = decrease time of digestion
How does feed intake affect energy intake?
More the cow eats the more energy intake
3 reasons why microbial efficiency might be increased with increased rumen turnover?
- Increased rumen turnover favors faster growing bacteria so more protein produced
- More bacteria in exponential phase of growth rather than maintenance
- Decrease protozoa to eat bacteria when dilution rate increased (washed away with rumen material)
What is wrong with feeding pelleted dehydrated alfalfa to sheep?
Too much rumen turnover
- Goes full pellets go into GI which causes for GI to be hypertonic which pulls water in causes liquid feces
6 reasons why rumen environment is conducive to microbial growth
- Acidity - pH is relatively constant
- Temperature - Warm 39-40C
- Motility - Mixes ingested feed with microbes and removes VFAs from site
- Substrate and Moisture - Constant
- Waste products - removed
- Anaerobic
3 possible locations of rumen bacteria
Single Cells or Clumps (unattached) 50%
Attached to feed
Attached to rumen epithelium
2 classes of bacteria in rumen
Primary Bacteria - directly ferment feed
- Amylotic
- Cellulolytic
Secondary Bacteria - Use byproducts produced by primary bacteria
What VFA does the following bacteria produce?
Fibrobacter succinogenes
Succinate
What VFA does the following bacteria produce?
Ruminococcus Albus
Acetate
What VFA does the following bacteria produce?
Selenomonas ruminantium
Proprionate (Randomizing)
What VFA does the following bacteria produce?
Methanobrevibacter
Methane
