Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
18 Cards in this Set
- Front
- Back
|
what are the losses due to subclinical/ chronic hypomagnesaemia?
|
depressed DMI decreased milk yeild loss in BC increased susceptibility to other diseases- milk fever |
|
|
when does acute hypomagnesaemia classically occur?
|
SPRING AND AUTUMN grazing
|
|
|
what are the specific homeostatic control mechanisms for regulation of Mg levels?
|
there are none
|
|
|
what is the amount of Mg in extracellular fluid dependant on?
|
absorption of Mg from GIT- low 10-35% requirement for Mg for milk production, tissues and endogenous losses. extretion by kidneys- where excess excreted. |
|
|
how much Mg is absorbed from GIT? |
10-35%
|
|
|
what factors can influence availability of Mg to cow?
|
soil levels, pasture species- legumes contain more. DMI. K- disrupt absorption of Mg and decrease Na in rumen. Na- carries Mg through rumen wall. rumen pH- absorption decreased with increased pH. dietary energy- FME to increase absorption. dietary fibre- increase gut transit time to increase absorption. genetics. redristribution of Mg in body- stress- catecholamines decrease plasma Mg levels. and high levels of insulin. |
|
|
what is the onset of clinical signs related to the concentration of Mg in?
|
CSF- will only fall at low blood Mg levels.
|
|
|
clinical signs of peracute hypomagnesaemia?
|
sudden death
|
|
|
clinical signs of acute hypomagnesaemia?
|
initially apprehensive, nervous and hyperaesthetic. rapid progression to collapse in lateral recumbancy and convulsions. 30% will die. |
|
|
what can progression to convulsions in acute hypomagnesaemia be causes by?
|
stress
|
|
|
clinical signs of subclinical/ chronic hypomagnesaemia?
|
often unrecognised. slightly nervous, reluctant to be milked or herded, depressed DMI and loss of milk yield. occasionally can progress to acute. could also be hypocalcaemic |
|
|
when might you see milk tetany in calves?
|
veal calves
|
|
|
what will plasma Mg be to indicate subclinical hypomagnesaemia?
|
less than 0.8mmol/l
|
|
|
how can you diagnose hypomagnesaemia at PM?
|
Mg in CSF Mg in urine Mg in vitreous/ aqueous humour |
|
|
why might you choose to measure Mg in vitreous humour over CSF?
|
vitreous humour Mg levels stable for 48 hours. CSF- freshly dead animals only. |
|
|
how would you treat an individual case of hypomagnesaemia?
|
ASAP- EMERGENCY remember that any sudden stimulus can precipitate fatal convulsions. take blood sample prior treatment- Ca, Mg and P levels. give 400ml 40% Ca borogluconate and 5% magnesium hyppphosphite slow iv. 400ml 25% magnesium sulphate subcut warmed prior in and 3-4 injection sites. control seizures- xylazine or ACP slow iv. TLC.- keep quiet in lateral recumbancy after. ensure adequate dietary Mg to prevent relapse. |
|
|
how can you approach a herd problem of subclinical hypomagnesaemia?
|
need 30g of Mg daily/ cow include in concentrate ration- 60g magnesium oxide per cow per day. medicate water supply with soluble magnesium salts (chloride, sulphate or acetate) mineral supplements- usually unpalatable. dusting/ spraying pastures. intra ruminal boluses |
|
|
how can you prevent hypomagnesaemia?
|
adequate Mg supplementation.Mg fertilisers for soil levels.pasture species with higher Mg.DMI maintained.minimise potash fertilisers and slurry that increase K.Na supplementation.limit use of nitrogenous fertilisers to limit ammonia.ensure dietary energy.avoid excess dietary fates.provision of adequate fibre- silage/hayavoid stress- sudden diet changes, protect from cold, wet weather.
|
