Studies on the aetiology and prophylaxis of hypomagnesaemia in ruminant animals

Ritchie, Norman S (1966) Studies on the aetiology and prophylaxis of hypomagnesaemia in ruminant animals. PhD thesis, University of Glasgow.

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The history and occurrence of hypomagnesaemia and hypomagnesaemic tetany in ruminant animals has been reviewed with reference to literature reports of previous investigations. A study was made over three consecutive spring seasons on the effect of potassium fertilisation of pasture on the development of hypomagnesaemia in lactating ewes. No effect was found in the first two years but where the potassium fertiliser was applied for the third successive year, significant depressions in the mean plasma magnesium concentration of ewes grazing thereon were found. Studies were also made into the effects of age, breed and number of suckled lambs on the development of hypomagnesaemia in Sheep. Age was found to have little influence. The suckling of either single or twin lambs was found to have no effect in one experiment but in a second trial, a greater incidence of hypomagnesaemia was demonstrated in ewes with twin lambs. Differences were found between two breeds of sheep in their relative susceptibility to hypomagnesaemia. Highly significant correlations were demonstrated between the plasma magnesium concentrations of individual ewes in consecutive years. By collation of existing literature reports, it was demonstrated that 80 - 90% of reported olinical cases in castle and sheep had a concomitant hypomagnesaemia and hypocaloaemis. The hypomagnesaemia was shown to develop rapidly over the 24 hours proceding the appearance of clinical signs. An experiment is described where an attempt was made to reproduce this situation of hypomagnesaemia in combination with hypomagnesaemia. No clinical cases were recorded. Studies were made with sheep to assess the value of existing prophylactic measures which are recommended for hypomagnesaemic tetany. The daily administration of magnesium salts, containing 4 g. magnesium, to sheep was found to produce only a small temporary response in the plasma magnesium concentration and this response was not maintained over a 24 hour period. A pasture application of 5 owts of oalcined magnesite per acre produced significant increases in the plasma magnesium concentration of grazing sheep. There was no response from the use only 0.5 owts/acre, when applied as a fertiliser in the winter, but this quantity, when applied as a pasture dust, inoreased the plasma magnesium concentration of sheep grasing thereon. As a possible new method of prophylaxis, a rumen pellet, containing a metal magneaium/aluminium alloy, was developed, this pellet was shown to corrode in the rumeno-reticular sac at a regular rate over a period of sir to eight weeks. Seven trials were carried out on sir farms to test the efficiency of a treatment of magnesium rumen pellets as a prophylactic measure for hypomagnesaemic tetany in cattle, sheep and oalves. In a total of 181 animals given this treatment, there were no olinical cases of tetany, whereas in a similar number of comparable control animals, there were six cases of hypomagnesaemic tetany. A response to treatment in the mean plasma magnesium levels was also demonstrated in five of the seven trails.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: J BS Inglis
Keywords: Animal diseases
Date of Award: 1966
Depositing User: Enlighten Team
Unique ID: glathesis:1966-72938
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06

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