Ruminant GI Tract Flashcards
Orientation of Stomach Compartments
Left side: Rumen, reticulum
Right side: Omasum, abomasum
How many permanent upper incisors does a 3 year old ewe have?
None. All ruminants have 0 because they have a dental pad.
Which side is a cannula always placed on and why?
Left. That’s where the rumen is.
What is secreted into the rumen?
Nothing.
Definition of Fermentation
Anaerobic digestion of feed material
The three types of microbes that live in the rumen
Bacteria, Fungi, Protozoa
Which animal enzymes can digest fiber?
None. This is why bacteria especially are needed.
What is the main source of energy for ruminants?
VFAs–the microbial waste products.
Which microbe is primarily responsible for digesting the ruminant’s dietary fiber?
Bacteria
Characteristics of VFAs
Smell bad, soluble in water, volatilized easily.
Where do VFAs go once they are absorbed through the rumen wall?
Enter the portal vein and go to the liver.
What nutrients are absorbed through the rumen wall?
Only VFAs and water.
How many bacteria are in the rumen (per mL of rumen fluid)?
10 billion
How many protozoa are in the rumen (per mL of rumen fluid)?
100,000
How do fungi aid in feed digestion?
They grow “roots” that help break food particles apart.
Types of Rumen Bacteria
Hundreds and hundreds. The predominant type present will depend on what the animal is eating (grain vs. forage).
What are you really feeding when you feed ruminants?
The microbes
What pH level bothers the fiber-digesting bacteria?
Drops in pH below 6.0
Where can the bacteria be located in the rumen?
Free-floating, feed adherent, or along the edge of the rumen wall.
How much of the ruminal bacteria is feed adherent?
3/4 of it.
What do feed adherent bacteria commonly digest?
Fibrous feeds
What do free-floating bacteria commonly digest?
Starch and other soluble substrates.
What types of bacteria live along the edge of the rumen wall?
Facultative.
Characteristics of Facultative Bacteria
They CAN use oxygen. They have urease activity–they break amino groups off urea to make microbial protein.
When does VFA build-up in the rumen occur?
Never since the VFAs are constantly absorbed through the rumen wall.
The Three VFAs and the Number of Carbons in Each
Acetate (3 carbons), Propionate (2 carbons), and Butyrate (4 carbons)
Predominant VFAs on a High Forage Diet
70% acetate
20% propionate
7% butyrate
Predominant VFAs on High Concentrate Diet
55% acetate
35% propionate
7% butyrate
*Have same amount of acetate as on high forage diet but have more propionate also which makes total amount of VFAs higher on a largely grain diet because the grain is so fermentable
Gases Produced During Fermentation
CO2 and CH4
How are the gases produced during fermenation gotten rid of and why can it be a good and bad thing?
Eructation. Losing carbons means losing energy. Losing hydrogen is good because it prevents the pH from getting too low.
What can the animal do with the VFAs?
Propionate: the liver converts it to glucose then sends it to tissues for use
Acetate: Goes directly to tissues for use, muscle uses it for main energy source
Butyrate: … it’s not glucogenic
What bacteria provide to the ruminant animal?
VFAs for energy, vitamins (all B vitamins), high quality protein.
What happens to the ruminal pH after the sheep/goat eats a meal?
The pH drops.
What pH inhibits fiber-digesting bacteria?
pH below 6
What are amylolytic bacteria and what pH are they sensitive to?
Starch-digesting bacteria, more sensitive to higher pHs, not inhibited by the lower pH of eating a meal.
What enzyme is secreted in the abomasum?
Pepsin
What happens in the abomasum?
Microbes are killed because of the low pH because of hydrochloric acid and they start to get digested with the animal’s feed.
What enzymes are secreted in the small intestine and which ones are important?
Pancreatic lipase, pancreatic amylase, and pancreatic proteases. Only the proteases are really needed. Dietary protein and microbial protein must be broken down in the small intestine.
What part of fat digestion/absorption takes place in the small intestine?
Fat is digested in the rumen and individual fatty acids are absorbed in the small intestine.
How can fatty acids be broken apart?
Oxidation
How are newborn ruminants considered according to their GI tract?
They are more like monogastrics since their rumen is not functioning.
How long does it take for the rumen to develop?
6 weeks
What stimulates ruminoreticulum development?
Eating fiber. The scratching of the solid feed stimulates the muscle contractions of the ruminoreticulum.
What causes the papillae to grow?
VFAs
What is another name for the reticular groove? What is the function of the reticular groove?
Esophageal groove. Milk bypasses the rumen via this groove and goes straight to abomasum to avoid being fermented in the rumen.
How are nutrient requirements determined?
They are based on the intended purpose of the animal—>their production.
What have dairy goats been genetically selected for? How are dairy goats fed?
High milk production and we feed them similar to dairy cows.
What type of goats have lower nutrient requirements and why?
Brush/Spanish goats because they have fewer offspring and produce less milk.
