L8: Lactation Flashcards
period following parturition where the reproductive tract returns to its non-pregnant state
puerperium
what is the economic benefit to shortening the puerperium in livestock
- increases frequency of breeding
- increased pregnancy in dairy cows increases their lifetime milk yield
what is lochia
blood, uterine lining and other discharge
what are the main events of puerperium
- myometrial contraction shrink the uterus and expel the lochia
- endometrial repair
- ovarian cycling resumes
- elimination of opportunistic bacterial infections
whaat is silent ovulation in bovines
after seasonal anestrus in the ewe or pregnancy in the cow, the ovary develops a follicle(s) that will ovulate without an accompanying behavior estrus
occur as two lines of tissue that run ventrally from the axial regio to the inguinal region
mammary ridges
name for the milk secreting cells of the mammary gland
parenchyma
what is the purpose of cisterns in species such as cows and goats
they increase the storage volume of the udder
most milk is stored within the _________ of the mammary tissue
alveoli system
what is lactogenesis
mammary epithelial cells are converted from a non-secretory state to a secretory state
increase in lactose, total protein, immunoglobulins
decrease in sodium and chloride
when does lactogenesis begin in cows
up to 4 days before parturition
what are the two stages of lactogenesis
prenatal cytologic and enzymatic differentiation of alveolar epithelial cells, driven by estrogen and prolactin
postnatal secretion of milk components
the sudden withdrawal of _______ at birth causes blood flow to mammary glands to increase
progesterone
T/F: milk production begins independent of newborn suckling
T
what is galactopoiesis
the maintenance of lactation once lactation has been established
what is involution
return to a non-secretory state
what are the two main components that contribute to the maintenance of lactation
galactopoietic hormones and the removal of accumulated milk (suckling)
what is the ‘first’ milk
colostrum
colostrum provides _______ immunity to newborn
passive
immunoglobulin absorption from the colostrum to newborn is limited to the first _______ hours of life
24-36 hrs
what molecule is important for the postresection adaptation response
IGF-1
glycoprotein w/ strong anit-microbial activity
lactoferrin
why does cheese color differ
due to nutrition and species differentiation of B-cartoene in their milk
white = grain fed
yellow = grass fed
what is the main E component of milk
fat
what is needed to break down lactose and what does it become
lactase
lactose—> glucose+galactose
composition of milk fat
mono, di and trigylcerides, FFA, phospholipids, steroids
composition of milk protein
casein, albumins, globulins
disaccharide composed of galactose and glucose
lactose
what hormones immediately decline with the birth of placenta
estrogen and progesterone
immediately after birth of placenta, ________’s role in milk synthesis is activated
prolactin’s
how is prolactin secretion inhibited when there is a lack of suckling
neurons in secretory parvocellular cells reelase dopamine
dopamine acts in anteriror pituitary to inhibit prolactin secretion
how does suckling lead to prolactin release
suckling stimulates nipple mechanoreceptors that synapse w/ neurosecretory cells in the hypothalamus
- inhibits dopamine
- stimulates vasoactive intestinal peptide
- release prolactin
how does oxytocin lead to milk let down
oxytocin causes contraction of myoepithelial cells which moves the milk into ducts and cistern
what are the steps in milk let down
- suckling/milking stimulates mechanoreceptors
- paraventricular nucleus cells release oxytocin via the posterior pituitary into blood stream
- oxytocin causes myoepithelial cells to contract, causes milk to move into ducts
- milk let down
milk fever occurs with the sudden demand in ________ that occurs w/ _______ production
Ca+
colostrum
explain how milk fever occurs
Hypocalcemia
- PTH secreted by parathyroid gland in response to low blood serum Ca
insufficient removal of milk can cause pressure ________
atrophy
mechanical pressure on alveolar epithelial milk secreting cells inhibits ______, resulting in ________
galactopoesis
involution
what is active involution
1-2 days of increased pressure inhibits milk secretion
Prolactin release is still responsive to feedback
what is steady state involution
sustained period of inhibited milk synthesis that lasts until the enxt birth
prolactin release is blocked
inflammation of udder and mammary gland in response to infection w/ bacteria, fungi, mycoplasma, algae
mastitis
what does mastitis cause
formation of non-funcitonal CT in order to wall off infection
What animal has 4 inguinal teats, with 1 cistern/canal per teat?
cow
What animal has 12-18 teats with 2 ducts per teat?
sow
What animal has 2 inguinal teats with 2 ducts per teat?
mare
What animals have 6-8 teats with 5-6 ducts per teat?
bitch and queen
What kind of cheese is typically made from sheep and goat milk or grain-fed cattle?
white
What kind of cheese is made from grass-fed cows or dyes such as annatto?
yellow
Where are proteins in milk (casein, albumins, globulins) synthesized?
ER
Without stimulation, neurons in the secretory parvocellular cells release _________ to inhibit prolactin secretion.
dopamine
Milk fever is characterized by depression, reduced activity, and paralysis. This issues are due to a decrease in ____________ and an increase in _____ that takes too long to correct the problem in the blood.
Calcium
PTH
Insufficient milk removal can lead to this
pressure atrophy