Vitamin D- Antirachitic Factor Flashcards
year that the term vitamin D was named for the antirachitic factor
1925
major role of vitamin D
promotion of Ca & P absorption
why is vitamin D thought of as a hormone
- active form made by an organ (kidneys) but travels to act on other organs (bone intestine)
- there are mechanisms for controlling synthesis and secretion of the active form
what is required for normal bone calcification
vitamin D
- amount varies with amount of Ca and P, and their ratio
what types of animals require the most vitamin D
- young and lactating animals
- swine and poultry
- wide Ca and P levels
2 hormones involved with vitamin D
calcitonin, PTH
lowers blood Ca levels and puts Ca back into bone
calcitonin
raises blood Ca levels and takes Ca out of bone
PTH
the disturbance of Ca & P metabolism; poor calcification of bones
-occurs in young
rickets
softening of bones in the chest; bowing of the chest
Pigeon-breast
importance of vitamin D to the adult; failure of bone matrix to be mineralized
osteomalacia
where does the body store vitamin D
mostly in the liver
3 vitamin D deficiencies in chickens
- thin egg shells
- lower hatchability
- lower egg production
vitamin D deficiencies in dairy cows
parturient paresis (milk fever)
what are the symptoms of parturient paresis
- lack of appetite
- dull and listless
- struggling & unable to stand
- low blood Ca and P
- coma
found in lactating cows up to 24 hrs after calving ; drains blood Ca into milk
true or false. Vitamin D2 and D3 are both effective for mammals.
true
vitamin D3 is ___ times more effective than vitamin D2 for chicks
30
“line test” based on observation of epiphyseal cartilage (in rats) – deplete the animal then feed graded levels of test material being assayed. Observe mineralization along edge of expanded cartilage. Measure degree of healing by comparing standard of vitamin D with test material.
curative method
% bone ash (chicks) – chicks fed assay material for 21 days. Then kill and measure ash in tibias. Compare a standard with the test.
preventative method
true or false. there is no active vitamin D in plants
true
rich sources of vitamin D
eggs (yolk), liver, fish oils, fishmeal’s, roughages - legumes, leafy alfalfa
some rat poisons have an excess of what vitamin
D
what practical problems could effect the intake level of vitamin D
confinement, winter weather, northern areas, long haircoat, high concentrate rations, aggravated Ca and P ratios, ruminant pre-intestinal destruction
vitamin D is sometimes called the____ vitamin
sunshine
