Exam 1 Flashcards
What are the primary enzymes for protein digestion? In the answer, include their sources and products.
Pepsin: source- abomasum, produce- long chain amino acids, breaks down polypeptides to peptides
Rennin: source- abomasum, produces curds
Trypsin: source pancreas, breaks down- peptides to aa
Name 3 major overall functions of rumen microorganisms
- microbial protein production
- degradation of feedstuffs
- absorption of their substrate gas production
Name 3 bacteria important for ruminal fiber degradation; briefly explain
Fibrinolysin- breaks down fiber feeds
Cellulolytic- breaks down cellulose
Starch- Break down fiber feeds
Explain the functions of each compartment of the ruminant stomach
Rumen- storage, fermentation, microbial degradation and protein production
Reticulum- scratch factor, form feed bolus for rechewing and regurgitation
Omasum- Filter, doesn’t let too large of particles through and water absorption
Abomasum- true stomach, produces HCl for break down and digestion of feeds as well as other enzymes that acid in breakdown
Explain the importance of esophagus groove and how it works
The esophagus groove moves milk diectly to the abomasum, bypassing the rumen and reticulum. This allows majority of the nutrients to be broken down and absorbed in the small intestine. If the milk were to enter the rumen first, it would be less efficient and lactic acid would be produced in the rumen. The groove forms as the calf is suckling from both a physical and chemical response.
Give 3 examples of primary digestive enzymes for (A) protein, (B) carbohydrates, be specific about source, substrate and products of each
A. Pepsin- secreted in abomasum and breaks polypeptides down to peptides
Trypsin- secreted from the pancrease, breaks down peptides into the amino acids
Chymotrypsin- secreted from the pancrease, breaks down peptides into the amino acids
B. Amylase- secreted with saliva, breaks amylopectin down to glucose
sucrase- secreted in the small intestine, breaks down sucrose to glucose
Lactase- secreted in the small intestine, breaks down lactose down to glucose
Advantages vs disadvantages of ruminants vs. non-ruminants
Ruminants- utilize feedstuffs, can acquire nutrients from fiber, utilize feed of by-products, and regurgitate
Disadvantage- microbes are fed concentrate ruminants become less efficient as the microbes convert less of the feed to a form the animal can use
Describe the GI tract in ruminants, discuss anatomy and physiology of each section in proper order
GI tract begins at the MOUTH
MOUTH- with teeth designed to grind and regurgitate food
Saliva (introduced)- high water content introduced for lubrication and buffering of the rumen
Mouth to esophagus- binds to the rumen which is composed of four sacs and openly connected with the reticulum
Reticulum- this is the fermentation vat where microbes break down nutrients as particles of feed as particle of feed sort out with larger pieces being sent back up to the mouth for further grinding
Rumen- is lined with finger like projections that assist in absorption
Rumen to reticulum- feed is passed through the omasum for further absorption into the abomasum
Abomasum- has mucus lining to protect from HCl secretes, along with other enzymes.
Nutrients go into the duodenum where the low pH is buffered and more enzymes are added. The jejenum aid the illeum follow, which are the sites for most of the absorption. The cecum is where some ferementation and absorption happens. Large intestine is the last portion to move the fecal matter through the colon and out the animal
What is the importance of pancreas for digestion
Produces- enzymes responsible for 50%- carbohydrate digestion 50% protein digestion 90% lipid digestion Produces- bicarbonate for neutralization of chyme in duodenum
What are the primary enzymes for carbohydrate digestion? In the answer, include their sources and products.
Maltose: (maltase) source- SI, produces- glucose
Lactose: (lactase) source- SI, produces- glucose and galactose
Sucrose: (sucrase) source- SI, produces- glucose and galactose
What are results in feeding ionophores?
- increased propionate
- reduced protein degradation
- reduced deamination
- reduced methane poduction
- reduced lactate production
What is the reticular groove?
Reflex in a calf from the suckling process that is a chemical stimulation. The lips close and form a canal to bypass reticulo-rumen milk through omasal groove to the abomasum. This gradually stops functioning as the calf starts to eat solid food
How does saliva work in ruminants?
Function: provision of fluid for fermentation, alkaline buffering which is critical for rumen pH
feed, water and saliva are delivered to the reticulum through the esophageal, no digestive enzymes
What are the proximate analysis?
Moisture Ash Crude protein Ether extract Crude fiber
What is the net effects of defaunation?
- Increased daily gain
- improved feed efficiency
- Decreased OM and cellulose digestion
- Increased total and microbial protein flow to the duodenum
What are 3 bacteria that are fibrolytic, briefly explain each
Ruminococcus spp.: major fibrolytic bacteria, needs NH3 for optimum growth, degradation of heavy forage
Butyrovibrio fibroslovens: substrates- starch, pectin, xylan, produce buyrate, demonstrates- proteolytic activity
Clostirdium spp: originate from silage, substrates- cellulose, starch, pectin, xylan, minor proteolytic
What are the Adv. and Disadv. of protozoa?
Adv.
Increased cellulose digestion- 25-33% of total cellulose dig., mechanisms- provide more NH3 to bacteria, remove O2
Slower fermentation of starch and sugars
Greater VFA production
Disadv.
increased rumen protein turnover
increased CH4 production
development of more virulent strains of pathogenic bacteria
What are some regulations of digestion
GI hormones/ peptides: Hormones secreted within GI tract affect digestion
Extrinsic/autonomic nervous system: Sympathetic- “fight or flight”, Parasympathetic- “Rest and digest”
Intrinsic/extrinsic nervous system: located in the GI tract- affects the digestive organs
What are fermentation end- products of cellulolytic bacteria
Cellobiose acetic acid butyric acid CO2 H2 Lactic acid
What are some factors that affect establishment of population
Presence of organisms: normally population is established through animal -animal contact, bacteria may establish without contact with mature ruminants
Favorable organisms: substrates and intermediates, increased rumen pH, digesta turnover
How does diet alter the rumen population
High forage: High pH, cellulose, hemicellulose, sugars, high cellulolytic bacteria, high protozoa
High concentrates: low pH, high starch, low cellulolytic bacteria, high amylolytic bacteria, low protozoa
If an animal was given ionophores what will happen?
Increases fibrobacter succinogens, prevotella rumicola, selenomonas ruminantium
Effects: decreases acetate, formate methane, decreases lactate, increased propionate
Why are inoculants used?
reduce lactic acid build up difficult for long term- antagonistic environment, difficult to get enough organisms, considerable gene exchange
Explain rumen fungi
fiber digestion
appear 8-10 days after birth
more prevalent on grasses than legumes, may be related to sulfur supplementation
what are the mechanisms for microbial inoculants
transformation
conjunction
transduction
What are the factors that depend on the type and amount of microbes
feed consumed- high forage and concentrate
max # in 2-3 high concentrate or 4-5 high forage
level of intake: high yields more
end products of fermentation are VFA, ammonia, gases
What are the VFA’s and what do they do
Acetate: mostly from cellulose, milk fat synthesis, cellulolytic bacteria, energy source for rumen epithelium and muscle, not utilized in liver
Propionate: mostly from starch, produce glucose, amylolytic bacteria, utilized by rumen epithelium, precursor for gluconeogenesis
Butyrate: mostly derived from acetate, ketone usage as an energy source, metabolized by rumen epithelium to ketone bodies
What happens with sudden dietary changes
Propionate to lactate; reduced pH
Lactate needs to be converted to pyruvate
Microbes converting lactate grow slow !!!!!
pH continues to drop
Too acidic environment
Lactic acidosis; can be lethal
How is pH altered
Diet
Intake
Feeding frequency
Chewing/rumination
What are regulation of mircrobial growth/function
Bacteria vs. protozoa Competition Environmental pH Alteration with diet Alteration with intake
