Slide Set 1: Biological Functions of Lactation Flashcards
What are the key charactestics of mammals?
- 4000 species
- Most of mammals are viviparous and possess hair
- The only vertebrates to have a mammary gland
- Feeding young by secretion from the mother
What are the animals that carry the mammalian characteristics but they are not mammals?
- piscus fish (produces milk from their skin, they don’t produce regular milk but it is more like a mucous substance to feed their young)
- pigeon, flamingo, emperor penguins
Pigeons secrete ___ milk
crop
What is crop?
Crop is a tissue between esophagus adn the top of the stomach. The main function of this region is to store food but 2 days before hatching the function of this tissue becomes producing milk.
What is the hormone that controls milk synthesis?
Prolactin
Prolactin is the msot important hormone for milk production in pigeons, rabbits, humand but NOT for _____
cows
What is the origin of the crop milk?
crop sloughed epithelial cells
What is the compostion of crop milk like?
Protein = 60% Fat = 30-35% CHO = 1-3%
No casein
No lactose
Baby pigeons are called
squabs
What determines the volume of milk?
High lactose means more diluted milk, lactose is responsible for the volume of the milk
How long does the laction lasts in pigeons?
10 days
What are the 2 subclasses of mammals?
Protheria (no placenta)
Theria (placenta)
What is the order of protehria?
monotemata (egg-laying mammals)
What are the 2 infa-classes of theria?
- metatheria (marsupials)
- eutheria (true placentals)
What are the key characteristics of metatherians?
- viviparous
- very immature young
- poorly developped placenta
- long lactation
What are the key characteristics of monotremes?
- Only two species still exist (Australia)
- Egg laying mammals (oviparous) - no placenta
- No placenta & mammary glands have no teats
- Young very immature and rely totally on milk
What are the two monotremes that still exist?
- Echidna (Spiny anteater)
- Duckbill platypus
What are the key characteristics of Echidna’s eggs?
- Eggs laid ~30 days after ovulation (single egg)
- Eggs incubated inside a pouch (10 days)
- Hatched young & very immature
How and when is echidna born?
After 10 days, young pierces egg shell with egg tooth
What are the key characteristics of a newborn echidna?
– 1⁄2 inch long
– Hind legs buds, front legs and toes well formed with tiny transparent claws for gripping the pouch hair
What are the key characteristics in lactation of echidna?
- Milk oozes into a depression within the pouch
* Suckling period for the young ~ 200 d
Explain the life cycle of a young echidna
- Carried in the pouch for ~ 53 days
- Suckles its mother once every 5 days
- May drink up to 20% of its body weight in milk daily
- Grows fast (from 0.5 g to 200 g in 2 months )
- When spines begin to appear, young is placed in a nursing burrow
- Leaves the burrow ~ 5 months and is weaned 4 weeks later
- Becomes independent ~ 1 year
What are the key characteristics of Duckbill platypus’ eggs?
• Lays 2 eggs 15 d after mating
• Eggs incubated in a burrow and
hatched in 10 to 14 d
• Hatched young are very immature
What are the key characteristics in lactation of duckbill platypus?
- Suckling period for the young ~100 d
- Milk oozes into stiff hairs in the abdomen
- Young suckles milk off stiff mammary hair on abdomen
- Young can take up to 20% of its body weight in 2 hours