L22- Milk Prod and Ketosis (#4) Flashcards
3 general developmental processes culminate in milk secreiton- what are they?
- Mammogenesis
- Lactogenesis
- Galactopoiesis
What is mammogenesis?
Mammary gland development
What is lactogenesis?
Induction of milk syntehsis
What does lactogenesis involve?
Regulation of gene expression and protein synthesis within the milk secreting epithelial cells
A few of genes turned during lactogenesis code for what 3 things?
- a-lactalbumin (required for lactose synthesis)
- Casein
- Several enzymes needed for Fatty acid synthesis
What is galactopoiesis?
The final stage of lactogenesis and refers to the mainteance of milk synthesis until it is no longer needed during an established lactation
Milking stimulates the release of _______(bST) which helps maintain milk produciton
Bovine somatotropin
Cows are in ________ during the first 12-14 wk of laction
Negative energy blaance
During the first month, cows may obtain one third of their energy needs from body stores resulting in a ______
50-100 lb wt loss!!
AA from lost muscle of cows during demands of milk production are used for _____ and _______
protein synthesis and
Gluconeogenesis
The ______ pathway for plasma components and leukocytes is open ONLY during pregnancy, involution, and inflammatory states like mastitis *
Paracellular*
Step 1 of pathway for milk secretion and synthesis by the mammary epithelial cell
I: Exocytosis of secretory vesicles containing milk protein, lactose, and other components of the aqueous phase
Step 2 of pathway for milk secretion and synthesis by the mammary epithelial cell
II: Milk fat secretion via the Milk fat globule (MFG)
Step 3 of pathway for milk secretion and synthesis by the mammary epithelial cell
III: Direct movement of the monovalent ions and water across the apical membrane of the cell
Step 4 of pathway for milk secretion and synthesis by the mammary epithelial cell
IV: Transcytosis of components of the interstitial space (immunoglobulins)
Step 5 of pathway for milk secretion and synthesis by the mammary epithelial cell
The paracellular pathway for plasma components and leukocytes. pathway V is only open during pregnancy, involution, and in inflammatory states such as mastitis
What is colostrum?
Special milk after parturition that is very high in proteins to act to improve the immune function of the calf
What are milk proteins?
Synthesizes on the RER and move onto the Golgi stacks where they are decorated with oligosacchardies and phosphorylated, etc
Class of milk proteins- describe the 1) solubility in acid, 2) protein(s), and 3) function(s) of WHEY** (vs caseins)!!
Whey (20% of total milk proteins):
-Soluble in acid
-Proteins: B-lactobulin (60% of total whey proteins)
a-Lactalbumin (25% of total whey proteins)
- Function:
B-lactobulin: no clear function possible a dietary protein
a-lactablumin: requred for lactose synthesis
Class of milk proteins- describe the 1) solubility in acid, 2) protein(s), and 3) function(s) of CASEINS** (vs whey)!!
Caseins (80% of total milk proteins):
-Insoluble in acid
-Proteins: Caseins (a,b,k)
- Function:
Slows gastric emptying after precipitation, increases bioavailability of CalciumCasein increase what in milk?
Bioavailability of calcium in milk (15% of calcium in milk is assoc with casein)
Whey proteins have a much higher _____ than casein
Biological value
Lactose synthesis requires what?
60-80% of the total daily glucose production
Cow preserves glucose for what purpsoe?
Lactose production
____________ is a dimer of galactosyltransferase plus a-lactalbumin!*
Lactose synthase
Lactose synthesis controls what?* How? (2)
Controls volume of milk produced
- Golgi vesicles are impermeable to lactose
- Once made, lactose is trapped inside vesicles and osmotically draws water inside thus determining the volume of milk
Energy in diet influences ___ production
Propionate
Propinate controls the amont of ____ formed
Glucose
Glucose controls the amount of _____ produced
Lactose
Lactose determines the volume of ____ produceds
milk
Lactose can be produced in 2 ways- from what two pathways?
AA–>a-lactalbumin–>lactose
Glucose- -> glucose –> lactose
What does de novo FA synthesis start with ? (2)
Acetate and B-hydroxybutyrate
FA are made where? what do they form?
Made on SER surface to form TAGS
What do TAGS do before forming the MFG?
coaslese into large droplets next to apical membrane and becomes enveloped into apical membrane that separates from cell as MFG
Membrane as 2 functions (apical membrane)
- Solubilzes milk fat and prevents fat globules from coaslescing into larger fat droplets in milk ducts which could prove difficult to secrete
- Primary dietary source of phospholipid and cholesterol for calf
High forage diet vs high grain diet- which increases butter fat?
High forage diet
What is something that has been shown to inhibit de novo FA snthesis acting at the gene level?
Very low levels of 3 specific conjugated LA
What are three dietary factors that increase the risk of MFD and prod of CLA? (whether working indiv or not)
- INCREASE IN DIETARY FAT- more substrate avail for biohydrogenation
- DECREASE IN RUMEN PH- will alter microbial populations such that bihydrogeation is favored
- MONENSIN decreases bacteria carrying out conventional biohydrogenation thus resulting in more of the CLA that inhibits fat synthesis
______ biohydrogenate linoleic acid forming CLA
RMO
What does a CLA look like?
Conjugated double bonds with no methylene group separating dbl bonds
The EFA, linoleic acid, is converted to __ acid in the rumen via biohydrogenation involving several CLA intermediates
Stearic acid
What is ketosis?
Common metab disease where energy needs are not being met and forced to use FA acids from her AT to make up the difference
Diagnosis of ketosis?
Based on elevated ketones in milk and urinalysis
Ketosis is triggered by a compination of factors which lower blood glucose and increase lipolysis- what are they? (2)
- Increased utilization of glucose
- Decreased glucose production
- 1&2 lead to hypoglycemia
What would hypoglycemia (tirggered by ketosis) trigger after leading to low insulin? (3)
- Increased lipolysis
- Increased B-oxid of FA
- Increased ketogenesis
- Ketonemia (elevated plasma FA)
FA in excess of those needed for B-oxid and ketogenesis are re-esterfied to form ___ and packaged in ____
TAG and packaged in VLDLs
VLDLs are slowly reelased from liver and excessive accumulations will result in a ______
fatty liver
One theory that explains ketosis is a shortage of hepatic ______
Oxaloacetate (OAA)
Shortage of OAA would be due to a decrease in what and an increase in what?
- NEB (neg E balance) would lead to less propionate and hence dec prod of OAA
- Inc rate of gluconeogenesis results in increased utilization of OAA
What does the shortage of OAA prevent?
Acetyl CoA from FA B-oxid from enterting TCA cycle and forces it into ketogenesis
Why is FA B-oxid activity high in liver early on in lactation? (2)
- A lot of ATP requred for gluconeogenesis (6 ATP equiv/ glucose formed)
- NEB foces cow to use fat from AT because rumen isnt supplying enough acetate
During fasting, low blood glucose activates lipolysis, which means and ___ in B-ox of FA, and OAA is __ because of (__ in gluconeogenesis, and __ in ruminant propionate prod), lower OAA will ___ entrance of ace coA into TCA cycle, and __ actyl coa is shunted into KETOGENESIS*
INCREASE, DECREASED, INCRASE, DECREASE, DECREASE, INCREASE
Type 1 ketosis: what serum ketones, glucose, on-set, BCS?*
Type 1 ketosis: Very high SERUM KETONES Low GLUCOSE ON SET IS 3-6 wks post calving BCS: thin
Type 2 ketosis: what serum ketones, glucose, on-set, BCS?
Type 2 ketosis: Moderately elevated SERUM KETONES normal GLUCOSE ONSET is within first 2 weeks after calving BCS: over conditioned
Ketosis is not life threatening but ketotic cows are more apt to develop what 3 things?
- Displaced abomasum
- Decreased mlk prod
- Difficulting conceiving
