Module 5- growth & lactation Flashcards
1
Q
where are hypothalamic factors released
A
stalk of anterior pituitary
2
Q
what does GnRH stimulate
A
stimulates GH secretion
3
Q
somatostatin
A
inhibits GH secretion
4
Q
grehlin
A
regulator of GH secretion, secreted in response to empty stomach
5
Q
T or F: stomach is an endocrine gland
A
T
6
Q
where are receptors of GH found
A
pituitary gland
7
Q
transcription vs translation
A
scription-DNA -> RNA
lation-RNA -> protein
8
Q
T or F: GnRH stimulates transcription & translation
A
T
9
Q
how is GH released? why?
A
GH is produced in cells in anterior pituitary & stored in vesicles
- vesicles allow a burst of hormone rather than taking a long time to make new
10
Q
T or F: somatostatin can be found in GI tract & other tissues as well as endocrine
A
T
11
Q
how many forms of somatostatin are there?
A
2
12
Q
BST
A
bovine somatotropin- used to improve milk production in E.coli
13
Q
where are GH receptors located (5)
A
liver, adipose, bone, muscle & gonads
14
Q
T or F: GH receptors in mammary epithelium
A
F
15
Q
T or F: GH is pulsatile
A
T
16
Q
why can you not take a single of GH & tell what the cows status is
A
b/c GH is pulsatile so it fluctuates so much and is not coordinated
17
Q
where is grehlin made
A
stomach lining
18
Q
where are ghrelin receptors located
A
hypothalamus
19
Q
what stimulates IGF-1?
A
GH
20
Q
how is IGF-1 produced/stored?
A
no vesicles, it is released slowly in several hours
21
Q
what is the major source of IGF-1?
A
liver
22
Q
anabolic vs mitogenic
A
a-synthesize proteins
m-cell perforation
23
Q
IGF-1 plays role in ( ) growth while IGF-2 plays role in ( ) growth
A
pre/post natal, utero/post natal
24
Q
IGF-1 has ( )% amino acid identity with insulin
A
50%
25
what are the 3 main tissues that express IGF-1
liver, uterus & ovary
26
why are IGF binding proteins used?
b/c we do not use vesicles
27
what is most abundant binding protein in blood? function?
IGFBP-3, protects IGF from degradation
28
what are the 2 main binding proteins secreted from liver? function?
IGFBP 1 & 2, reduce tissue availability of IGFs
29
direct vs indirect effects of GH
direct-act directly on receptors
indirect-things that IGF-1 does that stimulates GH
30
anti-lipogenic
stops making new fat & encourages breakdown of fat, GH inhibits insulin
31
lipolytic
breaks down fat, stimulates lipolysis = stimulates effect of epinephrine = releases energy from adipose tissue
32
what does GH need to stimulate more release when in a negative energy balance for anabolic/mitogenic functions of IGF-1
epinephrine
33
GH makes epinephrine ( ) potent
potent
34
insulin is ( ) potent in stimulating glucose uptake
less
35
GH secretion ( ) with grehlin
increases
36
low nutrition does what do IFG-1
liver makes less IGF-1 = less negative feedback to pituitary = stimulation of more GH
37
what 5 things occur in GH/IGF-1 levels during low nutrition?
1) increased GH from more grehlin
2) reduced number of GH receptors on liver b/c of lower protein synthesis
3) reduced IGF-1 secretion b/c of less receptors
4) increased IGFBP 1 & 2 and increased IGFBP-3
5) stimulates release of energy from adipose tissue for energy needs
38
example of direct & indirect effects of malnutrition on GH/IGF-1
direct: lipolytic, antagonizing insulin
indirect: reduced IGF-1
39
why are males larger than females
testosterone is more potent than estrogen in IGF-1 = increases GH pulsatility = more GH activity
40
effects of stress on IGF-1
increased cortisol = decrease in liver GH receptors = growth is reduced = lower effectiveness of IGF-1
41
effects of illness on IGF-1
cytokine hormone stimulates immune response when sick = directly reduces amount of liver production of IGF-1 = no appetite
42
nutrition & steroid effects on IGF-1
estradiol is more capable of stimulating IGF-1 in well fed animals
43
why does IGF-1 peak in high nutrition not low nutrition animals
b/c low nutrition directly inhibits the production of IGF-1 because of the lack of GH receptors on liver in low nutrition states
44
T or F: IGF-1 has no stimulating effects on animals with lack of management & feeding levels & stress
T
45
steroid impacts for cattle effects on GH
increases GH receptors on liver = increases GH pulsability
- does not work in monogastrics
46
why do plasma IGF-1 levels drop at day 21 & day 60 in pigs?
1) weaning is at 21 days = stress = cortisol increases = blocks GH receptors in liver = decline in IGF-1
2) change in environment = not eating = reduced nutrition = reduced IGF-1
3) exposure to pathogens= fighting change in gut microbiome b/c no milk anymore = cereal grains are different substrate for bacteria = immunosuppression = reduced appetite = loss of GH receptors on liver = drop in IGF-1
4) day 60: nursery -> grower barn = change in diet & environment = drop in IGF-1
47
why peak in GH at day 24?
1) low IGF-1 levels = reduced negative feedback = more GH
2) stomach is empty = makes ghrelin hormone = stimulates GH secretion
3) GH increases to make energy to support/maintain body function when they are not consuming feed
48
leptin
hormone that suppresses appetite by acting on hypothalamus & limits desire to eat
49
4 leptin functions
1) suppresses appetite
2) increases energy use
3) permits LH surge
4) Increases immune cell activity
50
what occurs with a mutation that no longer makes leptin
obese, hypoactive & low metabolic activity
51
where is leptin secreted
adipocytes
52
2 main drivers of leptin secretion
1) adiposity- increased with increased adipose size
2) energy balance- when no food = decreased leptin release
53
T or F: leptin is 2x higher in females than males
T
54
role of leptin cattle (2)
1) adds fat cover in finishing
2) as animals mature = reduce muscle growth & increasing fat growth
55
T or F: as you add fat, your appetite decreases
T
56
T or F: a reduction in appetite causes use of energy towards heat production but not for reproductive cycling
T
57
cattle genotype for leptin
wildtype = T allele = codes for cysteine (normal)
C allele= codes for arginine = reduced function
58
why does the T allele for leptin allow normal function?
b/c it codes for cysteine which has disulfide bonds to support protein binding
59
T or F: reduced function leptin ( C allele) changes the easy ability for fat cover
T
60
how is leptin managed?
genotypically- feeding & management are optimized to a particular genotype
61
myostatin
paracrine (local) hormone that results in double muscling phenotype if absent
62
what is the most common cattle breed for double muscling
belgian blue
63
how many myostatin mutations have been identified
5
64
what does double muscling mean
double the muscle fibers
65
where do most of the myostatin effects occur? why is it hard to occur?
Utero, hard to control with use of drugs
66
what test can be done for myostatin gene identification in humans
CRISPR
67
lactation
production of milk by the mammary gland, characteristic of all mammals
68
4 functions of lactation
1) provide milk
2) passive immunity of antibodies via colostrum
3) help gut development
4) promote beneficial intestinal bacteria
69
what nutrient is found in milk that promotes the growth of beneficial bacteria
polysaccharides (carb)
70
what is the mammary gland composed of
alveoli (spheres) that are made of a single layer of glandular cells
71
glandular cell function
synthesize milk & secrete it into the lumen
72
milk is an ( )
ultrafiltrate
73
how many L of blood transfers through mammary gland to get 1 L of milk?
600L
74
what are proteins, glucose & amino acids made into in milk
caseins / milk fats
75
T or F: blood moves rapidly through the gland
T
76
mammary vein
vein that passes along abdomen to gland that returns milk back to the circulatory system
- like a garden hose
77
each alveolus is surrounded by
myoepithelial (muscle cells) - looks like a spider
78
myoepithelial cell function
contract & force milk out of lumen of alveoli into a duct system
79
alveoli are arranged in groups called
lobules that turn into lobes
80
udder cistern
where milk is collected when it is forced into the duct system
81
movement of milk
alveoli -> lumen -> duct system -> utter cistern -> teat cistern -> teat canal (where milk exits)
82
where does milk exit out of
teat canal
83
what causes myoepithelial cells to contract?
oxytocin
84
where is oxytocin released from
posterior pituitary gland
85
the bovine suspensory system
bovine udder is composed of 4 separate mammary glands
86
suspensory ligaments
hold udder in place & supports the weight of the mammary gland
87
what would occur without suspensory ligaments
udder drag low = more susceptible to mastitis or injury
88
how much does the udder weigh
20 kg
89
ampullae in mammary gland
provide limited milk storage, similar to udder cistern
90
mammogenesis
mammary gland development
91
lactogenesis
initiation of milk synthesis
92
galactopoiesis
milk synthesis
93
when does mammogenesis occur
adolescence in begging of reproductive cycling during 1st cyclw
94
life cycle of dairy cow
0 days, 60-90 days, 305-320 days, 60 day
0=calving
60-90=re-breeding then lactation
305-320= drying off
60 day= dry period & breed again
95
when is peak lactation
during 1st nine weeks
96
how does drying off occur?
as lactation progresses, myoepithelial cells die = loss of milk synthesis capacity
97
drying off
stopping production of milk, lasts 2 months
98
T or F: female calf is born with rudimentary mammary system
T
99
mammary system at birth
udder has teat & gland cisterns but duct system is not really developed
100
mammary gland birth -> pre-pubertal period
mammary gland growth is isometric (grows at same time as rest of body), very little duct developement
101
how can overfeeding impact mammary gland formation
increased deposition of fat in mammary gland = limits further development of duct system
102
mammary gland at time of puberty
estrogen, progesterone & cortisol are released
103
what does estrogen & progesterone do for mammary gland growth?
estrogen- growth of cistern in ducts
progesterone-growth of alveoli
104
T or F: you cannot take a heifer that has not reached puberty & inject her with hormones to start producing milk
T
105
mammary gland during pregnancy
duct system develops & alveoli develop towards end of pregnancy
106
mammary gland around time of calving
1) surge of prolactin & decrease in progesterone
2) lactose synthesis
107
what is milk volume driven by?
lactose
108
how is lactose secreted
secreted into lumen & water follows by osmosis
109
T or F: caseins/proteins do not follow lactose by osmosis
T
110
what is lactose
small soluble sugar
111
what does a surge in prolactin cause?
drives initiation of lactogenesis
112
what hormone is high during pregnancy
progesterone
113
what is galactopoiesis driven by in cattle vs other spcies
cattle- GH
other- prolactin
114
what are the 3 most important hormones for milk synthesis
1) prolactin
2) GH
3) IGF-1
115
T or F: prolactin is higher during longer photoperiods
T
116
sow milk production increases with
litter size
more suckling = more prolactin = drives milk synthesis
117
peak milk yield
4-8 weeks then slowly declines
118
lactation curve
increase number of secretory cells after parturition = increased activity
119
what does decreased epithelial cell number mean
apoptosis
120
what to select for if you want a higher persistance
reduced apoptosis
121
milk let down is a ( ) reflec
neuro-hormonal
122
milk let down reflex
suckling / massing udder stimulates nerves in tit to send signal to posterior pit for oxytocin release = myoepithelial cells squeeze alveoli = forces milk out of duct system
123
how long does it take before milk let down occurs
1 min
124
when is peak of milk let down? how long does it last before all oxytocin is released?
peak is 2-3 min, lasts 6-8 mins before all oxytocin is released
125
what can inhibit milk let down
stress = vasoconstriction = no oxytocin release
126
fat in milk is 99% ( )
triglycerides
127
homogenization
rapid mixing of milk to turn large globules (float) into small globules so they stay mixed to avoid separation of milk
128
2 milk proteins
casein & whey
129
the epithelial cell of mammary gland
secretory vesicle is full of milk fat = pushed through plasma membrane of cell = plasma membrane forms surface of fat globule
130
how is fat in milk stored
in a globule that is surrounded by plasma membrane
131
what 2 components of milk are released into the lumen
lactose & proteins
132
what are solids in milk
what comes out at the bottom (protein & fat) when you spin milk rapidly in centrifuge
133
what type of milk is produced if there is less lactose
more concentrated b/c less lactose = draws less water into milk protein via osmosis
134
T or F: lactoferrin has health benefit
T
135
how are immunoglobins transported
taken from blood & moved into lumen across the epithelium
136
what is the primary source of immunoglobin for neonate
colostrum
137
4 factors affecting milk fat composition
1) milk fat %
2) milk fat composition
3) milk protein %
4) colostrum vs mature milk
138
colostrum has ( )x protein & ()x fat as mature milk
40x, 1.5x
139
what occurs if you freeze colostrum
freeze immune cells but can still have a healthy calf
140
what type of immunoglobin is colostrum mainly?
IgG
141
is IgA absorbed? why or why not?
not typically b/c it s very resistant to degradation in gut- present in mature milk
142
how does IgA work?
has 4 binding sites which are capable of joining pathogens together to inhibit their movement towards epithelium & supporting their removal via peristalsis
143
lactoferrin
binds iron to make it more available for neonate
144
why is iron given as an injection, not oral in neonates?
it can overwhelm lactoferrin & cause E.coli scours
145
what is the most limiting nutrient for bacteria/pathogens
iron
146
bacterostatic vs bacterocidal
static-prevents growth
cidal-kills
147
oligosacchardies
short complex sugar, is preferred nutrient for beneficial bacteria
148
how do beneficial bacteria take advantage of oligosaccharides
use it as a substrate
149
de novo synthesis
make on own
150
what type of synthesis does C4-C16 use
de novo
151
how are short & long chain FA made
short-synthesized in mammary gland & secreted
long-taken from diet or adipose tissue
152
ruminant vs monogastric milk composition
ruminant- higher in saturated fat
monogastric-reflects what the diet is - can be unsaturated or satured- no modulating effects
153
northern seal milk composition
do not eat during lactation = all fats comes from adipose
154
elephant milk synthesis
de novo synthesis
155
how many times a day should a cow be milked to increase milk yield
3x
156
4 effects of mastitis
1) infiltration of immune cells from blood into gland
2) destruction of alveoli
3) reduced milk production
4) negative economic impacts
157
why does milk production decrease with mastitis
neutrophils squeeze between 2 cells to get into alveoli to clear infection, they damage the epithelial cells
158
mastitis pathway
bacteria finds way through teats and duct system and then get into alveoli
159
somatic cells
cells with full chromosome
160
what does a high level of somatic cells in a dairy cow mean?
infection in the gland
161
how long is milk production reduced with mastitis
until there is drying off & another round of parturition for mammary gland growth
162
a somatic cell count <100,000 is (good/bad)
bad
163
what is the largest economic loss from mastitis from
reduced production
164
T or F: peak lactation is 6th lactation
T
165
hormone levels in mammogenesis
decrease progesterone, increase estrogen & cortisol, no change in prolactin
166
hormone levels in lactogenesis
peak production in estrogen, cortisol & prolactin, decrease progesterone
167
hormone levels in galactopoiesis
decrease progesterone, estrogen, cortisol & prolactin
