1 Introduction, Etiology, Risk Factors

Transcript

Greeting to all vets,

I welcome you all to the agMOOCs program on Metabolic disorders in Cattle, jointly organized by the Commonwealth of learning Canada and directed by extended education TANUVAS.

In this program, you could have seen a series of lectures on various Metabolic disorders and this is the one among the common Metabolic syndrome in cattle, is Hypomagnesaemic Tetany in cattle otherwise known as Lactation Tetany, grass staggers, Transit Tetany, and Wheat pasture poisoning.

Normally Hypermagnesaemic Tetany occurs in lactating dairy cows, which is a high yielder, and in an acute form, there will be peracute mortality, so there will be excitatory neurological signs and the animal will die immediately, which is common in mainly inclement weather, especially cattle raised on a lush green pasture or a cereal grass crops.

And now the Hypercalcemia, the deficient dietary deficiency is rare in normal cattle only some metabolic factors influence the absorption of magnesium in lactating cow, and Parakeet form is common and Chronic form is characterized by that is a mostly occur concurrently with Hypercalcemia, so most the time Hypercalcemia cow they will not respond to routine treatment that is the specific treatment for calcium and their combined treatment of calcium magnesium will give a good result.

And Hypomagnesaemic Tetany in a calf is very common that are mainly raised on a whole milk or milk replacer diet without any roughage feeding those calfs the neurological signs are uncommon and the animal may die.

So, in this class, we are going to see about Hypomagnesaemic Tetany in dairy cattle. We are going to cover 5 lessons.

so lesson-1 is about the occurrence of Hypermagnesiuma and how what are all the risk factors involved in causing the disease and then the Etiology of Hypermagnesiuma and

In the lesson-2, we are going to see about the effect of Hypermagnesemia on various systems and then the various stages of Clinical syndrome manifested in animals and

then in lesson-3, we are going to see about how to Diagnose the Hypermagnesemia by various laboratory methods and then a differential Diagnosis and…

In lesson-4, the main part of the program is how to Manage Hypermagnesemia through different treatment protocols and then the Control of Hypermagnesemia.

finally, in lesson-5, we are going to see about the Occurrence of Hypomagnesaemic Tetany in calves and what are all the Clinical manifestation and how does it occurs, and the Treatment and Management.

Now we are moving on to lesson-1; so in a Hypomagnesaemic Tetany of cattle. In the first lesson, we are going to see is about -What is Hypomagnesaemic, How does it occur, What are all the risk factors involved in causing the Hypomagnesaemic and Magnesium Homeostasis, and the Etiology of Hypomagnesemia.

See Hypomagnesaemic is mainly occurring in lactating dairy cattle and mainly in the normal cow the deficiency will not occur because dietary input is sufficient, but certain factors predispose the cattle to go for a magnesium deficiency and the main magnesium is a major Intra solar divalent element and the excess of Magnesium is deposited in the bone and then muscles and tissue. So the main role of magnesium is it aids in the various enzymatic activity and mainly it exerts its function on the neuromuscular junction for the release of neurotransmitters, hence the deficiency mainly causes neurological signs in cattle.

So as I said it’s an important element for enzymatic activity and muscular function through the release of a neurotransmitter at a motor end plate and it mainly occurs in cattle raised on lush green pasture as well as cereal grass crops.

Now we are going to see how the Magnesium level in the serum is maintained in cattle. Normally unlike a hyper calcium homeostasis it is mainly under the control of a hormone in Hypercalcemia that is a Parathermone and Vitamin D3, but here there is no feedback mechanism to maintain the Magnesium status in cattle and mainly kidney playing a major role in the conservation of a magnesium whenever there is excess demand in cattle so you can see in cow the input of magnesium is through dietary source only then it once reaches the rumen where it’s mainly absorbed in the rumen epithelium through the sodium linked ATAPase mechanism, for that the rumen environment should have sufficient sodium potassium ratio of 5:1, that is important for the active transport of magnesium through the rumen epithelium and to certain extent the magnesium is absorbed in the small intestine and as well as abomasum and the excess is excreted in the feces and the absorbed Magnesium it goes to the kidney where the excess level is excreted in the tubules and in lactating dairy cattle apart from that is excretion in the urine phases there is excess loss of magnesium in the milk and normally the magnesium absorption is also deposited on the major bones, that is the reserve for magnesium as well as in the skeletal muscle to give the normal physiological activity.

So input and output whenever there is a dietary deficiency or some factors influence the absorption of magnesium on the rumen, then it predisposes the cattle to go for hypo magnesium so hence there is no feedback mechanism for a Hypomagnesaemic, that is the maintenance of magnesium in the serum it is only a kidney playing a role for the excretion or reabsorption of magnesium.

Now we are going to see about all the predisposing factors for the causation of Hypomagnesaemic, as the terminology says it’s a Wheat pasture poisoning or Grass Tetany, mainly cows that are raised on a lush green pasture, that is in grasses, especially during the winter season in grasses as well as they are fed with some cereal crop grass like wheat or barley or rice. So they are the main source, they contain excess potassium, so once the potassium content is more than sodium, then the ratio will get altered. So normal absorption of sodium is to potassium is 5:1, now the ratio decreases if the rate of potassium increases and sodium decreases is a 3:1. So the active transport of Magnesium through the rumen epithelium gets compromised, so this is the major cause of Hypomagnesaemic in dairy cattle.

Apart from that, there is a severe winter, and there will not be enough fodder to feed the anima, so the dietary deficiency of Magnesium also contributes to Hypomagnesemia. Apart from that, there is acid soil, like leaching of soil may lead to Hypomagnesaemic in a cattle. Fertilization of a pasture may cause that is excess Potassium containing fertilizers causing an altered sodium-potassium ratio in the rumen, so reduce the availability of Magnesium to the animal.

Causes: So as a whole Hypomagnesaemic; mainly it is caused by the factors like even Animal factors that is reduced dry matter intake and normally the concentrate feeds that favor the magnesium absorption the increased volatile fatty acids constituted by the constitute feeding improve the Magnesium absorption, so reduced dry matter is given to the animal, then the reduced volatile fatty acid then we reduce the absorption of magnesium in the rumen, and

Apart from that the period of there being an animal being transported during inclement weather then there also there is chances are there is a deprivation of food and sudden excitement like epinephrine or release, stress, and all these factors may predispose the animal to go for Hypomagnesemia.

The Etiology for Hypomagnesaemic is multi-factorial because even though one thing is dietary deficiency but it rarely occurs. Most of the time even though the diet is adequate, the altered sodium-potassium ratio may predispose the animal to go for Hypomagnesemia.

So it is a multifactorial disorder and it mainly occurs when the dietary magnesium concentration decreases from the normal value, that is 1.7 milligram to 3 milligrams, if it is less than 1.7 it is 1 milligram, then it will show neurological signs.

So What is Hypomagnesaemic, How it Occurs, and How the normal Magnesium Homeostasis is maintained in cattle, What are all the various Risk factors involved in that, and the function of a Magnesium.