Explain 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
What are the advantages and disadvantages of having an established protozoa population in the rumen?
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
Explain animal- and feed-related factors that affect feed intake
Physical fill: distention of the gut tells the animal to stop eating
Chemostatic: absorbed nutrient in blood is monitored by receptors in brain - tells animal to stop eating
What is the main function of Acetate
Acetate: mostly from cellulose
- Important for milk fat synthesis
- Cellulolytic bacteria
- Energy source for rumen epithelium and muscle
- Not utilized by liver
What is the main function of propionate
Propionate: mostly from starch
- Important to produce glucose
- Amylolytic bacteria
- Utilized by rumen epithelium
- Converted to lactate and pyruvate
- Important as a precursor for gluconeogenesis
What is the main function of Butyrate
Butyrate: mostly derived from acetate
- Important in ketones usage as an energy source
- Metabolized by rumen epithelium to ketone bodies (acetoacetate, beta-hydroxybutyrate)
- Later metabolized in liver
- Net ATP production is 25 per mole
Explain main characteristics of chylomicron
- large triglyceride rich particles
- made by the intestine
- involved in the transport of dietary triglycerides and cholesterol to peripheral tissues and liver.
- size of chylomicrons varies depending on the amount of fat ingested
- A high fat meal: large chylomicron
Explain main characteristics of VLDL
- Very low density lipoprotein
- are used for energy because they are more available and low density.
- Delivers endogenous lipids from the LIVER to FAT and MUSCLE cells with the help of LPL
- Becomes IDL
- Mostly triglycerides
Explain main characteristics of LDL
LDL: Low Density Lipoprotein
- used for cholesterol transfer by LDL receptors
- Delivers fat and cholesterol to cells (including arteries)
- Mostly Cholesterol- neg. impact, Atherogenic; Increases risk for heart disease
Explain main characteristics of IDL
IDL: Intermediate Density Lipoprotein
- Transient
- Little nutritional impact
- TAGs are removed…becomes LDL
- Mostly Triglycerides
Explain how each of the main VFA is produced in the rumen
• produced in large amounts through ruminal fermentation
• provide greater than 70% of the ruminant’s energy supply
• Acetic, proprionic and butyric acids formed in the rumen
- absorbed across the ruminal epithelium, from which they are carried by ruminal veins to the portal vein and hence through the liver.
1. Acetic acid is utilized minimally in the liver and is oxidized throughout most of the body to generate ATP.
2. Proprionic acid is almost completely removed from portal blood by the liver. Within the liver, proprionate serves as a major substrate for gluconeogenesis.
3. Butyric acid, most of which comes out of the rumen as the ketone beta-hydroxybutyric acid, is oxidized in many tissues for energy production.
Name all the factors that affect heat production (HP) and explain each in detail.
Factors that affect heat prod: Gender, nutrient absorbed, physiological state, ration characteristics, environmental conditions, GI tract, physical activity
Gender: basal met rate
Nutrient Absorbed: glucose is more efficient on cellular level
Physiological state: fetal growth, growth of animal
Ration characteristics: forage vs concentrate
Environmental conditions: thermoneutral zone
GI tract: ruminants vs monogastrics, bigger tracts require more maintence
Physical activity: grazing is less efficient than confined
Explain how Vitamin D, Ca, P are related
- When blood calcium is low= The parathyroid glands release parathyroid hormone (PTH), Stimulates conversion to calcitriol (active form)
- Increased active form of vitamin D: Increased absorption of calcium in the intestines, Increased reabsorption of calcium in the kidneys, Increased bone turnover (calcium is released from the bones)
- Calcitonin – promotes ossification of phosphorus onto matrix
- PTH – promotes resorption of phosphorus from bone and excretion in urine
- Calcitriol – promotes increased phosphorus absorption in the intestine
Explain how Vitamin E and Se are related
Part of glutathione peroxidase (antioxidant effects), High levels of vitamin E or selenium may inhibit the other’s effects, closely working with vitamin E, Antioxidant, incorporated into proteins to make selenoproteins, which are important antioxidant enzymes.
What are ionophores? Explain a) the mode of action, b) their advantages, and c) name two examples
Define: a lipid-soluble substance capable of transporting specific ions through cellular membranes.
Mode of Action: compounds that alter rumen fermentation patterns. They disrupt the ion concentration gradient across microorganisms.
Advantages: increase feed efficiency and body weight gain, higher feed intake with similar feed conversion
Examples: vancomycin and nigericin
Explain how proteins are degraded and partitioned in ruminants; start with dietary protein and go all the way to end-products
Protein is ingested into the rumen as energy in the feed
• Becomes digestible energy (DE) -> Losses: fecal, undigested food, metabolic
• Metabolic energy: HP, recovered energy -> Losses: waste energy urine
Protein is separated into two different groups -> Rumen degradable, undegradable
Rumen Degradable
• VFAs, microbes, CH4, CO2, FAs, Glycerol -> out, direct absorption, abomasum
• ABOMASUM -> absorption
Rumen Undegradable
• Digestible
• Indigestible
Absorption
• ABOMASUM
• SI
• LI -> excretion
Describe what happens in the rumen when you feed Canola oil to a goat
Overfeeding= microbes don’t like this -> a lot of omega-3, reduced fiber digestion, decreased intake
Canola: high energy, double bonds= unsaturated (18:2)-> Biohydrogenation
Too much canola oil creates less biohydrogenation
Biohydrogenation
• Addition of hydrogen ions to unsaturated FA -> replacing double bonds to single
• Creating less unsaturation in rumen
• Unsaturated (18:2) -> CLA (conjugated linoleic acid) 18:2 -> trans (18:1) -> Steric (18:0) (saturated)
• Lipid digestion: happens in SI
• Lipase: produced by cells in pancreas (in SI, by ducts)
• Bile: from liver, contains phospholipids and bile salts (aids by breaking up fat into small droplets, increases surface area)
• Stomach churning and bile salts emulsify the lipids: Increases the accessibility of fat to digestive enzymes, Increases surface area of dietary lipids -> EMULSIFICATION
• EMULSIFICATION: (Stomach) fat and watery digestive juices separate (enzymes are in water and can’t get to the fat
- Fat enters SI
- Bile has an affinity for fat and water -> bile can mix fat into water
- After Emulsification -> more fat is exposed to enzymes and fat digestion moves on
• Broken down into micelles
• Absorption happens in SI into lymph as fat droplets from micelles called CHYLOMICRONS
• Lymphatic system will spread throughout the body by portal vein
Explain how P are digested, absorbed, metabolized, function
- Function: bone mineral - 80% of body P is in skeleton, ATP, Phospholipids, RNA
- Absorption: Passive from G.I. tract, Saturable – carrier mediated active transport, Concentration-dependent facilitated diffusion
- Digested: Cleaved from proteins, sugars and lipids
- Metabolized: Circulating is in equilibrium with skeletal & cellular, Found in all cells, especially bone and muscle
Explain Vitamin A (forms, digestion, absorption, sources, functions and metabolism, deficiency, etc.)
- Function: Vision: Maintains normal vision in dim light, formation of Rhodopsin, Epithelium (skin integrity), Reproduction, Skeletal growth, Immune system
- Deficiency: Degeneration of mucosa of respiratory tract, mouth, salivary glands, intestinal tract, and kidneys, Night blindness (decreased formation of Rhodopsin), Later stages permanent eye damage, Dry skin, immune dysfunction
- Forms: retinol, retinal, retinoic acid,
- Sources: green leafy forages
- Absorbed: intestinal lumen, absorbed similar to lipids, converted to beta-carotene
- Metabolized: Retinol is the immediate precursor to two important active metabolites: retinal, which plays a critical role in vision, and retinoic acid, which serves as an intracellular messenger that affects transcription of a number of genes. Carotenoids such as beta-carotene that can be converted to vitamin A within the intestine and other tissues.
- Digested: Carotinoids in green plants serve can be converted to vitamin A following ingestion.
Explain how P are digested, absorbed, metabolized, function
- Function: bone mineral - 80% of body P is in skeleton, ATP, Phospholipids, RNA
- Absorption: Passive from G.I. tract, Saturable – carrier mediated active transport, Concentration-dependent facilitated diffusion
- Digested: Cleaved from proteins, sugars and lipids
- Metabolized: Circulating is in equilibrium with skeletal & cellular, Found in all cells, especially bone and muscle
Explain how Vitamin E are digested, absorbed, metabolized, function
- Function: Antioxidant - 1. prevents rancidification of fats in plants 2. Prevents body cells from oxidative damage. Integrity of red blood cells, Heart and skeletal muscle respiration, spares Selenium, Reproduction
- Digested: De‐esterification prior to absorption via pancreatic and brush-border enzymes
- Absorbed: Passive diffusion, Formed into micelles
- Metabolized: intestinal absorption, vascular transport, hepatic sorting by intracellular binding proteins, such as the significant α-tocopherol-transfer protein, and hepatic metabolism.
Explain how Se are digested, absorbed, metabolized, function.
- Function: (trace mineral), growth, fertility, inhibits glycolysis,
- Digested: microbial digestion occurs in the rumen and reticulum that digests in the abomasum and SI
- Absorbed: duodenum and cecum by active transport through a sodium pump
- Metabolized: The liver is the central organ for selenium regulation and produces excretory selenium forms to regulate whole-body selenium. It responds to selenium deficiency by curtailing excretion and secreting.
Why efficiencies with which ME is used for different purposes differ? Explain
ME is utilized for many things in the body.
- HP: includes Basal met, heat of fermentation, thermal regulation
- Retained energy
- Waste energy
- Urine
- Gaseous enery
- ME is used for mainly determined by animal requirements
- Animal producing milk then the ME requirements must be used to maintain body condition before being used in milk production
