Ruminant Anatomy and Physiology Flashcards
What are the 4 regions of the ruminant stomach?
- Reticulum –> rumen –> omasum –> abomasum
Describe the stomachs in a newborn calf
- Abomasum is largest –> needed for digestion rather than fermentation
Describe the stomach in a 5 YO cow
- Rumen is now large and takes up whole left side of abdomen
- Liver is pushed up cranially
Describe the stomach of a 6 YO pregnant cow
- Uterus displaces rumen dorsally and abomasum cranially
What feed causes the rumen to become functional?
- Grain
What structure allows milk to bypass the rumen and enter the abomasum in the calf? What happens when milk enters the rumen?
- Oesophageal groove
- Rumen putrefaction
What organisms are found in the rumen and what are their functions?
- Bacteria –> digest cellulose (only seen with EM)
- Protozoa –> control bacteria numbers
- Fungi – aid bacteria in cellulose digestion
What is the “true” stomach of the cow
Abomasum
What is the purpose of external ruminal palpation?
- Helps determines the consistency of the rumen contents
Why do you want to auscultate the rumen?
- Determine rate/ strength of rumen contractions, rumen volume, and rumen contents
What is atony?
- Complete absence of reticuloruminal motility
How does atony occur?
- Absence of excitatory inputs or increase in inhibitory inputs to the gastric center of the hypothalamus
- Depression of gastric center
- Vagal failure or motor pathway failure
What is hypomotility?
reduction in frequency or strength of primary contraction
How does hypomotility occur?
- Decreased excitatory drive to gastric center
- Increased inhibitory inputs
- Weakness of the motor pathway
What is the importance of primary contraction frequency?
- Indicates the overall health of the rumen
What can prevent secondary/ eructation cycle?
- The cardia being blocked by foam or fluid
What occurs during rumination
- Food is broken down further
- Saliva is ingested, adding bicarb to decreases acidity of rumen contents
What are you looking for when examining feces?
- Amount, color, odor, consistency, degree of digestion
How can you collect rumen fluid?
- Ororuminal collection and rumenocentesis (better)
What must you be aware of with rumen samples
- Quickly test sample as protozoa activity changes over time
What are normal colors of rumen fluid?
- Olive to brownish grey for hay
- Yellowish brown for grain/ silage ration
What are abnormal rumen colors?
- Black/ green for rumen stasis
- Milky gray/ brown is lactic acidosis
What is considered normal rumen consistency? Abnormal?
- Normal –> slightly viscous
- Abnormal –> waterly (anorexia), frothy (bloat or vagal indigestionn)
What are normal and abnormal rumen odors?
- Normal –> aromatic
- Abnormal –> acidic (lactic acidosis), rotting odor (rumen putrefaction)
When is the best time to measure rumen pH? What is the normal rumen pH? Abnormal?
- Best to measure 2-4 hrs after concentrate or 4-8 hrs after TMR
- Grass feed is pH 6-7
- TMR 5.5-6
- > 5.5 is lactic acidosis
What is the purpose of methylene blue reduction?
- Indicates anaerobic ruminal bacteria
- Normal is 2-6 min
- > 10 min is transfaunation
What is the purpose of nitrate reduction test?
- Measures abomasal disease, abomasal reflux, obstruction of intestinal flow
How can you clinically assess the abomasum?
- Percussion and auscultation, abdominocentesis, blood work
