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Flashcards in Ruminant Physiology Deck (52)
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1

Special features of ruminants

- able to utilize forages other mammals cannot digest
- forestomachs
- esophageal and reticulo-omasal groove to bypass rumen
- no upper incisors or canine teeth (dental pad)

2

Members of ruminant class

- cattle
- sheep
- goats: low fiber, discriminant/browser
- camelids (pseudoruminant)

3

Location of forestomach

- rumen/reticulum is on the left side
- omasum is in the middle
- abomasum is on the right side

4

Advantages

- break down cellulose to usable nutrients
- allows synthesis of high biological value protein: low biological plant protein, non-protein nitrogen, nitrogenous end product (urea)
- production of all B vitamins

5

Disadvantages

- regular food intake at regular intervals
- long hours chewing: food ingestion (4-7 hrs/day), chewing cud (8 hrs/day)
- keep rumen fermentation vat balanced: large quantities of alkaline saliva, constant mixing, release of gas products

6

Rumen layers

- gas
- fiber mat/raft
- fluid slurry (small particles)

7

Roughages

Cellulolytic
- cellulose: glucose
- hemicellulose: xylose
- pectin: galactose

8

Legumes

Cellulolytic
- able to fix nitrogen (high protein)

9

Grains

Amylolytic
- starches
- simple sugars

10

Requirements for fermentation

- regular addition of fresh food
- presence of suitable microbes
- steady removal of end products: gas, VFA, simple compounds, undigestible material
- continuous mixing
- propulsion of fine particles and fluid
- anaerobic
- stability: temperature, osmotic pressure, redox and pH

11

Protozoa

- live in fiber mat
- very sensitive to change
- feed on bacteria, plant starch and PUFAs
- provide high biological value protein
- prefer pH of 6.2

12

10^10 bacteria/gram rumen content

Cellulolytic bacteria
- pH of 6.2
Amylolytic bacteria
- pH of 5.8
Lactobacillus spp.
- takes over at pH <5.8
- lactic acid producing (creates rumen acidosis)

13

Rumen dysfunction

- normal rumen pH 5.5-7.0
- rapid feed changes
- oral antibiotics
- die off of normal rumen fauna

14

Rapid feed changes cause

- acute acidosis/grain overload: pH < 5.0
- subactue acidosis/SARA: pH < 5.5
- takes 2 weeks for rumen fauna to adjust

15

Products of fermentation

- gases: methane (CH4 and CO2) is eructated
- volatile fatty acids: absorbed across rumen wall
- microbial and protozoal protein and lipids: passed thru to abomasum
- ammonia: absorbed across rumen wall

16

Volatile fatty acids

- acetate: ketogenic
- butyrate: ketogenic
- propionate: glucogenic
- ketone bodies: acetone, acetoacetate, betahydroxybutyrate

17

Is glucose available for absorption?

NO
- blood glucose levels in ruminants is lower
- insulin is lower

18

Acetic acid

- minimal liver use
- oxidized throughout most of the body to generate ATO
- major source of acetyl CoA for synthesis of lipids

19

Proprionic acid

- major liver use: removed from portal blood by liver
- serves as a major substrate for gluconeogenesis
- critical to the ruminant because almost no glucose reaches the small intestine for absorption

20

Butyric acid

- comes out of the rumen as the ketone beta-hydroxybutyric acid
- oxidized in many tissues for energy production

21

How long does it take to fast a ruminant

24-48 hrs of no food, 12 hrs no water

22

High fiber diets produce more _____

Acetate and butyrate
- higher butterfat in milk

23

High grain diets produce more ______

Proprionate
- higher milk volume but lower butterfat

24

Protein metabolism

Broken down to simplest form (ammonia)
- deamination of plant proteins
- urea from diet and saliva
- may feed up to 30% urea in diet (NPN)
- utilization of urea requires adequate energy in form of VFA or starch

25

Gas production

Up to 40 L/hour 204 hours after a meal

26

Green house gases

- water vapor, carbon dioxide, methane, nitrous oxide, and ozone
- carbon dioxide, CH4, and N2O
- fossil fuel combustion, iron and steel prodution, cement manufacturing and municipal solid waste combustion

27

Methane makes up _____ of green house gases

7.9%

28

_______ has decreased, but milk production has increased 4 x per cow

Number of dairy cows
- working on feed additive to decrease methane

29

Rumen motility/rumination

- mixes rumen fermentation vat continuously
- allows for regular release of gas (eructation)
- allows for cud chewing: reduces particle size and increases saliva flow
- filters fluid and particulate matter thru to omasum and abomasum

30

Innervation of forestomachs

Parasympathetic
- vagus, CN 10
- promotes rumination, cud chewing
Sympathetic
- thoracic ganglia to celiac
- decreases motility
Nervous cows
- drip/drool saliva
- decrease (increase/hypermotile) rumen contractions