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Flashcards in Minerals Deck (37):
1

How can mineral deficiencies occur?

Low mins. in diet
Low absorption
Thru mineral interactions (formation of unabsorbable compounds; comp. for metabolic pathway)

2

Storage & function of minerals?

Held in different compartments (central reserve plus one or more reserves)
Many have multiple functions
Most have catalytic function
Some have physiological function (Na, Ca, Cl, K)
Some have regulatory function (Zn)

3

A bit about Calcium

Most abundant min in body (in bone)
Essential for: bone/tooth dev.; enzyme systems for normal muscle & nerve function; blood clotting

4

Blood calcium homeostatic range?

80-120 mg/L

5

Good sources of calcium?

milk
green, leafy crops
animal products containing bone
limestone

6

Factors that affect calcium:phosphorus ratio?

High P binds Ca -> - Ca absorption
Low vitamin D -> - Ca utilisation

7

Recommended Ca:P ratio?

1:1 or 2:1

8

Feed with best Ca:P ratio?

Oaten hay

9

Feed with highest Ca content?

Lucerne hay

10

A bit about vitamin D

2 forms - D2 & D3
Found in cut forages
Produced by skin under UV light
Stored in liver
Works with PTH -> maintain plasma [Ca]

11

Good sources of vitamin D?

Sunlight & sun-cured forages

12

Consequences of Ca deficiency/ P excess...?

Rickets - young animals
Milk fever
Developmental orthopaedic disease (DOD) young horses
Osteomalacia & osteoporosis - older animals

13

Effects of -Ca and ++P?

Hyperparathyroidism -> bone demineralisation (as bone minerals mobilised -> +fibrous connective tissue -> bone enlargement (eg big head)

14

Symptoms & clinical signs of hypocalcaemia?

Clinical hypocalcaemia -> Milk fever/parturient paresis/paralysis
Inappetence
Lat recumbency
Coma & death

15

What constitutes hypocalcaemia (mm/L)?

Ca < 1.4mm/L

16

T or F - Ca is the most common mineral-related problem of the transition cow

True

17

Mineral availability in digesta occurs as...?

Easily absorbed - metallic ions in solution (Na/K)
Some absorbed - constituents of metallo-organic substances
Not absorbed - parts of insoluble substance

18

T or F - Minerals can not be converted between different forms

False - they can, depending on pH

19

Availability of minerals from other sources?

P as phytic acid
In milk > solid food
Chelated minerals

20

Incidence of hypocalcaemia?

Aus: 1.6 - 5.4% (>20% some herds)
US/UK: 6% (US - up to 70% clinical/subclinical hypocalcaemia)

21

Ca increase in Ca homeostasis...?

Dietary vit D2 & D3 & Ca -> +calcitriol (kidney) -> + Ca pool (3g plasma & 10g extracellular)
Parathyroid gland secretes PTH -> +calcitriol (kidney) & + bone breakdown -> +Ca

22

Ca decrease in Ca homeostasis...?

Thyroid gland -> calcitonin -> bone mineralisation -> -Ca pools
Kidney calcitonin -> +Ca excretion in urine
Milk/foetal losses
Faecal losses

23

Factors that cause hypocalcaemia after lactogenesis?

Inability to absorb Ca from gut & mobilise Ca from bone during lactogenesis
Ca requirement doubles during lactation (23g) in 10kg of colostrum

24

How long does it take for Ca mobilisation to occur to increase absorption?

3-4 days (most hypocalcaemia occurs soon after calving)

25

Nutritional causes of hypocalcaemia?

- Ca (diet & maternal reserves)
K
Mg
P
Na

26

Low Ca intake pre calving stimulates what?

Calcitriol

27

K properties &

pastures may contain 4-5% [K]

28

Effects of excess K...?

Excess -> metabolic alkalosis -> decreased sensitivity of bone & renal tissue to PTH
-> prevents upregulation of 1,alpha-hydroxylase

29

Hypomagnesaemia effects on Ca homeostasis?

Decreased mobility of Ca
PTH & calcitriol activity retarded

30

Phosphorus causes what?

hypocalcaemia -> PTH action on renal tissue
Keep <35g/day pre calving

31

Na properties and potential effects...?

Stronger cation than K
May cause metabolic alkalosis

32

Dietary options for reducing milk fever?

Ca & vit D
Manipulating DCAD (feeding anionic salts)
Replenishing Ca reserves

33

DCAD stands for...?

Dietary cation-anion difference

34

Why is DCAD important? How?

Lowering DCAD -> lowers pH -> improves Ca homeostasis
Also -> reduces risk of metabolic acidosis

35

Common anionic salts

CaCl2; CaSO4; MgCl2

36

DCAD should be at what value to prevent MF?

-10 ideally

37

T or F - DCAD can not be manipulated without anionic salts

False