Post-partum And Lactation Flashcards
What is the period of puerperium in cattle?
Parturition to first postpartum estrus
What is puerperium?
The physiological and anatomical readjustments in the ovary and uterus that take place after parturition in order to restore normal reproductive activities.
What is the period of puerperium in sheep?
Parturition to next breeding season
What happens during puerperium?
- Involution of the uterus
- Lochia
What is Lochia?
Uterine discharge - mucous, blood shreds of fetal membranes, maternal tissue and fetal fluids in the first week after parturition.
What is involved in the Involution of the uterus?
Myometrial contractions, elimination of bacterial infections, and regeneration of the endometrium, reduction of uterus size
During Involution of the uterus, how is the uterus reduced in size?
My myometrial contractions and PGF2alpha secretions
How could a bacterial infection develop? What types of bacterial infections might there be?
The cervix is dilated, allowing bacteria in and the environment of the uterus is extremely favourable for bacterial growth.
- Attracts pathogenic and non-pathogenic bacteria.
What is the defence mechanisms employed during the Involution of the uterus?
- polymorphonuclear infiltration
- massive release of PGF which is used by the immune system to attract more cells to the site of inflammation
- release of estrogen
What takes longer: the Involution of the diffuse placenta or cotyledonary placenta?
Involution of the cotyledonary placenta
What suspends ovarian activity?
Lactation
How do you get around lactation preventing ovarian activity?
- selection
- nutrition
- weaning
True or false? First ovulation after parturition is preceded by estrous behavior.
False.
What prolongs the interval between parturition and estrus?
- presence of the calf (suckling and milking)
How does suckling induce anestrus or prevent ovulation?
- prevents release of GnRH, LH and FSH
- failure of ovaries to respond to gonadotropins
What is lactation?
The final stage of the reproductive cycle in which milk and colostrum is produced
What is colostrum?
The “first milk” that is important for immune transfer
- has more solids than regular milk and is yellowish in color
What are the major anatomical structures of the udder?
- teat
- streak canal
- teat cistern
- gland cistern
- milk ducts and ductules
- lobes and lobules
- alveoli
What are alveoli cells?
Secretory epithelial cells
What are myoepithelial cells in the alveoli involved in?
Milk ejection
What are the phases of mammary growth?
- Prenatal phase
- Postnatal phase
- Pregnancy
In the prenatal phase, what is happening in the mammary gland?
- early development
- no hormonal control
In the postnatal phase, what happens to the mammary gland?
Puberty
During pregnancy, what happens to the mammary gland?
- complete development
- hormonal control
What hormones are involved in the control of the mammary gland growth?
- estrogen and progesterone
- growth hormone
- prolactin and placental lactogen (ruminants)
- ACTH/glucocorticoids/thyroid hormones
How is growth hormone involved in mammary gland development?
- provides support and nutrients
- necessary but not limiting to growth
What does prolactin and placental lactogen act on during gestation?
Lobulo-alveolar system
What is ACTH/glucocorticoids/thyroid hormones important for in terms of mammary glands?
- metabolic activity
- necessary for maximum development
Where does lactogenesis happen?
In the alveolar cells of the mammary gland which are able to synthesize and secrete milk
What is lactogenesis driven by?
Hormones - estrogen, prolactin, ACTH, insulin and growth hormone
How is more insulin diverted to lactogenesis?
Insulin receptivity decreases in the body so less glucose is taken up by bodily systems. Since mammary glands have a different mechanism for the uptake of insulin, this energy can be used for lactogenesis.
How is lactation maintained?
- control of cell number
- metabolic activity
- efficient milk ejection reflex
What is involved in hormonal secretion and milk removal?
prolactin, growth hormone, ACTH, thyroid hormones (T3 T4), PTH, Insulin, oxytocin
What mobilized energy towards the mammary gland?
GH, IGF-1, Insulin
What is responsible for controlling calcium requirements?
PTH and vitamin D
What does milk removal do?
- triggers prolactin
- decreases pressure - increases blood flow
- feed back inhibitor of lactation (FIL)
What is milk ejection controlled/induced by?
- Pressure builds up
- Afferent mammary nerves and external environment generate conditioned response to spinal cord
- Spinal cord sends signal to SON and PVN of hypothalamus
- Hypothalamus sends signals to the posterior pituitary and blood stream
- blood stream causes myoepithelial cells to contract
- posterior pituitary causes release of oxytocin
What is the external environment involved in milk ejection?
- visual, auditory, milking routine
- certain breeds require offspring
What causes inhibition of milk ejection?
- stressful situations
- catecholamines (Vasoconstriction + receptor competitor_
–> epinephrine and norepinephrine
-
What is mammary gland involution?
mammary gland goes from the lactating state back to the non-lactating state
What happens during mammary gland involution?
- gradual process
- apoptosis
- decrease in lactose and casein
- increase in IgG and lactoferrin
How is the involution of the mammary gland a gradual process?
- weaning/drying off –> lack of stimulation to the mammary gland reduces production
- Lactation curve
What happens during the apoptosis in mammary gland involution?
- rapid loss of tissue function
- degeneration of alveoli
- loss of mammary epithelial cells
What are the three phases of mammary gland involution?
- Active involution (30 days)
- steady state (short)
- Redevelopment –> colostrogenesis
Why is the involution of the mammary gland important?
- necessary for maximum production
- increase susceptibility to new infections
What is colostrum?
- first product to be synthesised during lactation
- more solids than regular milk
- fat, protein, CHO, IgG’s, calcium, etc
- important for passive immune transfer
what does the composition of milk vary with?
feed, season, breed and stage of lactation
In terms of milk composition, what changes the most between breeds?
proteins, carbohydrates and fats change the most
Why is it so important for the calves to get colostrum quickly?
- cause absorption by the newborn digestive tract is maximum in the first 6-12 hours
- great amounts of immunoglobulins, particularly IgG is transferred from the mother to the offspring (Passively) via intracellular passage in the small intestine
How is the quality of colostrum measured?
by the amount of IgG’s in the colostrum –> associated with density and total protein
