Lactation Flashcards
Lactation
the production of milk by the mammary gland
What gland is the mammary gland?
exocrine gland
What does the mammary gland produce?
the external secretion of milk transported through a series of ducts
What is the udder supported by?
horizontally and laterally by suspensory ligaments
What is the purpose of lactation?
-provide nutrition to offspring
-passive immunity source
How many teats do cows have?
4 - each with their own mammary gland
Alveoli
-secretory tissue of the mammary glands
-appear as sac like structures
-lined with epithelial cells that produce milk
-millions within each mammary gland
-each has its own blood supply
Epithelial cells
secretory cells that produce milk during lactation
-line the alveoli
Where does alveoli empty the milk produced into?
ducts that eventually lead to the gland cistern
Orifice
-opening to the papillary duct
-normally held closed by the sphincter muscle in the wall of the teat and elastic tissue
-invasion here is the primary route inf most cases of mastitis
Streak canal
-located at the end of each teat
-1/4-1/2 in long
-made up of extensions of the skin that lie close together
-held closed by sphincter muscles
-prevents the escape of milk between milking
-acts as a barrier to the entry of bacteria
Teat cistern
-final storage area of milk
-base of the udder
-large collection area
-milk letdown
Gland cistern
-bottom of udder
-located just above the teat cistern
-acts as a milk reservoir
Supramammary lymph glands
act as filters that destroy and remove bacteria from the udder
Supernumerary teats
-50% heifers
-extra teats (functional)
-usually removed
What happens when a cow is milked?
1.sphincter muscles relax
2. the orifice opens
3. the streak canal opens and remains open for one hour after milking
Estrogen function in mammary growth
responsible for the growth of the primary and secondary ducts and teat and gland cisterns
Progesterone in mammary growth
stimulates the growth of the alveoli
What is responsible for the initiation of lactation?
growth hormone, adrenal corticoids, and prolactin
Oxytocin role in mammary growth
released by suckling reflex; contraction of the myoepithelial cells in the alveoli
What happens when milking/suckling stops?
alveoli distend and the capillaries fill with blood
Factors affecting milk production
-inheritance/genetics
-feed
-management
-health
-sex of offspring (increased for male; decreased for female)
-# of offspring (increased for more offspring)
-age (really young or really old is a decreased milk production)
Colostrum
-first milk females produce after calving
-milk obtained during the first milking
-it contains more proteins, minerals, and milk fat
-less lactose
Transition milk
the next several milking after the colostrum
Immunoglobulins
-involved in passive immunity
-necessary for the fetal immune system to survive
-sometimes they are transferred in utero through the bloodstream
-usually transferred through colostrum
-give protection from harmful microorganism that invade the body and cause illness
Milk fat
-mixture of lipids existing as microscopic globules suspended in milk
-fat soluble vitamins are components
-contains more flavor
Carbohydrates
-lactose is the predominant carb in milk
-milk is the only natural source of lactose
-synthesized in the mammary gland
-4.8% of milk is lactose
-accounts for 30% of total calories in milk
-1/6 as sweet as sucrose
Proteins
-high quality
-3.3% protein
-22% of the calories in whole milk
-Casein is the main protein (only found in milk)
-contains whey proteins lactalbumin and lactoglobulin
Vitamins
all vitamins essential for humans nutrition are found in milk
Minerals
rich source of calcium and a good source of phosphorus and zinc
