Hypomagnesaemic Tetany Research Articles

Factors influencing magnesium absorption and metabolism in ruminants.

Magnesium is a nutrient required for all animals, but it is especially critical for ruminants. A physiological deficiency of Mg results in hypomagnesemic tetany. Typically, only female ruminants are affected, and the disturbance usually occurs during the early stages of lactation. Magnesium functions at three biochemical levels, as a cofactor at the enzymatic level, at the structural level in assembly of ribosomes, and at the whole cell level as a stabilizing force in membranes. Parathyroid hormone (PTH) can affect Mg metabolism by decreasing urinary Mg excretion and stimulating bone resorption, thus releasing Mg into the extracellular fluid. Renal excretion of Mg and Mg absorption from the gastrointestinal tract both are increased by 1,25-dihydroxyvitamin D3. A number of dietary factors depress Mg absorption in ruminants. Of these, high dietary K has the greatest and most consistent effect. Feeding substantial quantities of readily digested carbohydrates increases Mg absorption, but the mode of action is not clear. High concentrations of Al in forage sometimes are associated with a high incidence of grass tetany, but this effect does not appear to be related to Mg absorption. Interrelationships of Al with Mg, Ca, P and PTH are implicated.

CLINICAL AND LABORATORY STUDIES ON CERTAIN ASPECTS OF HYPOMAGNESAEMIC TETANY IN CALVES: I. CLINICAL SIGNS AND ESTIMATION OF SOME BLOOD ELEMENTS AND ENZYMES

This study was designed to determine for the first time in Iraq the clinical and biochemical changes occured in calves affected with hypomagnesaemic tetany. Fifty clinically normal calves and 50 calves showing symptoms of hypomagnesaemic tetany were used in the present study. Their ages ranged from 2-7 months. Clinical signs of affected animals were registered. Blood samples were taken from the 2 groups of animals to determine the levels of magnesium, calcium, phosphorous, potassium, sodium as well as 2 of the serum enzymes (SCOT & CPK). Tetany group of animals showed significantly decrease (P<0.01) in both Mg. & Ca levels reaching (0.804 ± 0.027) and (5.574 t 0.197) Mg./100 ml. serum respectively. The potassium levels were markedly increased (6.010 土 0.162) mEq/L. serum, while the phosphorous levels were dropped slightly. On the other hand, both serum enzymes (SGOT & CPK) were highly elevated (P < 0.01) and the data were (160.24 ± 4.881) unit/1 ml. serum and (781.516 ± 63.444) unit/1 liter serum respectively.

Epidemiology of Metabolic Disorders in the Periparturient Dairy Cow

The descriptive epidemiology and risk factors were reviewed for six clinical disorders: milk fever, downer cow syndrome, hypomagnesemic tetany, udder edema, left displaced abomasum, and ketosis. Data were included also from preliminary analyses of a data set from ∼61,000 Finnish Ayrshire cows. A web of postulated associations among the metabolic disorders and other risk factors (previous lactation diseases and milk yield, calf factors, certain dry period nutritional factors, dystocia, retained placenta, and metritis) was diagrammed.

Calcium, Phosphorus, and Magnesium Homeostasis in Ruminants

Significant advances have been made in the last 30 years in the understanding of Ca, PO4, and Mg homeostasis in ruminants. Despite these advances, the primary cellular or molecular lesions responsible for failure of homeostasis have yet to be identified. Suggested causes, such as primary hormone deficiencies, have been eliminated, and we now believe that aging and nutrition can reduce the ability of intestine, bone, and kidney to respond rapidly to the hormone signals responsible for homeostasis during rapid increases in demand for these minerals. Further research is required before these lesions can be identified and new knowledge applied to the development of economical, effective programs that prevent milk fever and hypomagnesemic tetany. Until then, diseases such as milk fever will continue to affect 8 to 9 per cent of our dairy cows, and dairy farmers will continue to spend millions of dollars a year for treatment of the primary disease and the many secondary problems that result from these diseases.

Hypomagnesemic Tetany of Ruminants

Hypomagnesemic tetany of ruminants is a noninfectious metabolic disorder that occurs in a wide range of nutritional and management conditions. This article considers its etiology and pathogenesis, clinical signs, clinical pathology and lesions, diagnosis, clinical management, prevention, and control.

The effect of induced hypomagnesaemia and hypermagnesaemia on the erythrocyte magnesium concentration in cattle

Hypomagnesaemia was induced in ten yearling Friesian heifers by starving them for forty hours while hypermagnesaemia was induced in seven Friesian calves (about two and half months old) by intramuscular magnesium sulphate (MgSO4) injection. The plasma magnesium (PMg) concentration decreased (P less than 0.05) during starvation and increased (P less than 0.05) following MgSO4 administration. However the erythrocyte magnesium (EMg) concentration did not show any significant change either with starvation or following the MgSO4 administration. These results show that sudden and significant changes in PMg concentration do not have any significant effect on EMg concentration. Accordingly EMg concentration may be a better indicator of long-term body Mg status and during hypomagnesaemic tetany could show whether the decrease in PMg concentration was sudden or gradual.

Macromineral absorption in sheep fed tetany-prone and non-tetany-prone hays.

Two experiments were conducted to determine some of the factors that led to hypomagnesemic tetany associated with the feeding of two orchardgrass hays. Sixteen mature Columbia and Suffolk wethers (62 to 72 kg), four of which were fitted with ruminal and abomasal cannulae, were fed one of two tetany-prone orchardgrass hays or a non-tetany-prone bromegrass hay. In Exp. 1, 12 wethers were used in a completely random design metabolism experiment to measure apparent absorption and retention of macrominerals. In Exp. 2, four wethers with ruminal and abomasal cannulae were used in a completely random design experiment to monitor pre-intestinal mineral absorption and ruminal characteristics. This experiment was replicated once, with wethers remaining on their diets for 16 d in each replication. In the metabolism experiment, apparent absorption and retention of Mg as a percentage of intake were lower (P less than .01 and P less than .05) for one tetany-prone orchardgrass hay compared with the other orchardgrass hay. Pre-intestinal absorption of Mg in the cannulated wethers was greater (P less than .01) for the orchardgrass hays than for the bromegrass hay. Pre-intestinal Mg absorption was higher (P less than .01), both in terms of grams per day and a percentage of intake for the orchardgrass hay with the highest Mg content. In the noncannulated wethers, the percentage of water-soluble Mg in the feces was lower (P less than .01) for the tetany-prone hays, indicating that a decrease in Mg solubility in the intestine may have influenced Mg apparent absorption.(ABSTRACT TRUNCATED AT 250 WORDS)

An Epidemiological and Genetic Study on Registered Diseases in Finnish Ayrshire Cattle

The epidemiology of clinical ketosis, hypocalcaemia and hypomagnesaemia was examined. In addition, the genetic variability of ketosis and parturient paresis was investigated. The data set consisted of the lactation records of 70,775 Finnish Ayrshire dairy cows. Each cow was under observation for 2 days before and for 305 days after calving. Lactation incidence rates (%) were: ketosis 6.0, parturient paresis 3.8, non-parturient paresis 0.6, hypomagnesaemic tetany, outdoor 0.6, and indoor 0.2. These diseases formed 22 % of all first treatments by veterinarians during farm visits. 92 % of the cases of ketosis occurred with 8 weeks of parturition, with the highest occurrence 3–5 weeks after calving. Four % of cases of parturient paresis occurred before, and 45 % within 24 h after calving. When cases were categorized by month of calving the risk of ketosis was higher during indoor feeding (October-April) than during outdoor feeding (May-September). The risk of parturient paresis did not significantly vary with month of calving. The occurrence of ketosis increased with parity up to the 4th and decreased thereafter. The occurrence of parturient paresis increased with parity. Both the increase in herd milk yield and the increase in individual milk yields were positively associated with the occurrence of ketosis and parturient paresis. The cows with a history of the reproductive tract infection had a higher risk of contracting ketosis. Heritability estimates for ketosis in various parity groups were from 1.6 % to 4.1 % on the binomial scale (corresponding to 7.3 %–14.4 % on the normal scale), and for parturient paresis from 3.5 to 10.5% (corresponding from 18.3 % to 27.4 %). The genetic correlation between ketosis and parturient paresis, and these and current milk production for all material were insignificant.

Hypomagnesaemic tetany associated with prolonged treatment with aminoglycosides

Hypomagnesaemic tetany associated with prolonged treatment with aminoglycosides

Hypomagnesaemic tetany associated with prolonged treatment with aminoglycosides

Hypomagnesaemic tetany associated with prolonged treatment with aminoglycosides

INFLUENCE OF READILY-AVAILABLE CARBOHYDRATES ON MAGNESIUM ABSORPTION IN RUMINANTS

Supplementing orchardgrass (Dactylus glomerata L.) hay with glucose, sucrose, lactose or starch increased apparent magnesium absorption in sheep. In subsequent experiments ruminai infusion of a glucose solution increased apparent magnesium absorption, but infusing hydrochloric acid (HCl) or a mixture of buffered or unbuffered propionate and butyrate in solution did not affect absorption. Key words: Carbohydrate, hypomagnesemic tetany, magnesium absorption, sheep.

Experimental studies on hypomagnesemia in ruminants: effects of varying calcium content in low-magnesium diets on serum concentrations of magnesium and calcium, and heart rate in lactating ewes.

In order to elucidate the relationship between hypomagnesemic tetany and Ca metabolism in ruminants, experiments were carried out on four 2-year-old lactating ewes divided into two groups (A and B) according to the order of feeding of two low-Mg diets (8.4mg/kg of body weight/day) with varying Ca contents (normal-Ca: 154.5 and low-Ca: 26.1mg/kg of body weight/day). Serum Mg and Ca concentrations as well as heart rate (HR) as an indicator for signs of hypomagnesemic tetany were determined every day throughout the experimental periods. On feeding either the low-Mg and normal-Ca diet or the low-Mg and low-Ca diet the decreased dietary levels of Mg resulted in a significant fall of serum Mg concentration (0.5-0.7mg/100ml). Serum Ca concentration gradually fell on feeding the low-Mg and low-Ca diet. On feeding the low-Mg and normal-Ca diet it temporarily fell and then returned nearly to the control level. Consequently, serum Ca/Mg ratio rised more remarkably on feeding the low-Mg and normal-Ca diet than the low-Mg and low-Ca diet. The significant increase in HR, or the onset of hypomagnesemic tetany was always preceded by remarkable rise in serum Ca/Mg ratio on feeding the low-Mg and normal-Ca diet. It is suggested that the imbalance in dietary Ca/Mg ratio might enlarge the imbalance of Ca/Mg ratio in extracellular and intracellular fluid resulting in the hypomagnesemic tetany in lactating ewes.

SOME EFFECTS OF TOPDRESSING PASTURE WITH SODIUM CHLORIDE ON PLANT AND ANIMAL NUTRITION

A long term study is being made of the effects of replacing all or part of the fertiliser input of potassium chloride (muriate of potash - KCI) with sodium chloride (common salt - NaCI) on plant and beef animal nutrition. The ryegrass-white clover pasture which is growing on a sodium deficient pumice derived soil (Taupo sandy silt), had received heavy applications of KCI over the preceeding 10 years. Results from the first two years show that because of the already high potassium status of the pasture, neither KCI or NaCl had any effect on pasture dry matter production or species composition, but did effect the chemical composition. Topdressing with NaCl at rates of 100-200 kg/ha/vr significantly increased the herbage sodium concentrations, while similar rates of 'KC1 increased potassium concentrations but decreased sodium concentrations. However, the depressing affects of KC1 on sodium concentrations were offset by applying 50 kg/ha/yr of NaCI. increasing the sodium concenrrarron In me neruaye au"ve V, I 70 VI LIIG UIY IUU~LLXZI with NaCl had a beneficial effect on the growth of weaner beef animals. However, increasing the sodium intake of beef breeding cows grazing pastures high in potassium had a detrimental effect on the concentration of magnesium in the blood serum. Thus, as a relatively high intake of sodium may induce metabolic problems in breeding cows, topdressing pastures or direct supplementation of animals with NaCI, should not be undertaken without sound evidence of its necessity particularly in areas prone to grass staggers (hypomagnesaemic tetany). Key Words: animal nutrition, herbage sodium; plant nutrition; potassium chloride; ryegrass-white clover pasture, sodium chloride, serum magnesium.

Renal function and magnesium clearance in young and old cows given potassium chloride and sodium citrate.

Six young (3 yr old) and six old (8 to 11 yr old) cows were used to examine renal function, KCl and sodium citrate effects on Mg clearance rate and the relation of parathyroid hormone (PTH) to Mg reabsorption. The treatments were 1.5 g KCl/kg body weight (BW) and 1.5 g Na citrate/kg BW. Inulin and p-aminohippuric acid (PAH) clearance rates were used as measures of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), respectively, in control cows on each treatment day. Creatinine clearance rate was also used as a measure of GFR in all cows. Magnesium loading (2.4 mg/kg BW) through continuous intrajugular infusion of MgCl2 facilitated the measurement of changes in Mg clearance rate and reabsorption due to treatment. Inulin and creatinine clearance rates were not different as measures of GFR, and there were no differences in ERPF between young and old cows. Old cows had lower (P less than .05) GFR, creatinine to PAH clearance ratios and tubular reabsorption of Mg than young cows. Intraruminal infusion of KCl and Na citrate increased (P less than .05) the GFR. Potassium chloride increased plasma K concentration (P less than .001), plasma K clearance rate (P less than .002), plasma Na clearance rate (P less than .03), plasma Mg concentration (P less than .05), net tubular reabsorption of Mg (P less than .02), maximum tubular reabsorption of Mg (P less than .002) and plasma PTH concentration (P less than .03). Plasma Mg clearance rate was increased only by Na citrate (P less than .05). These results suggest a possible relationship between age, renal function, Mg antagonists and PTH in Mg homeostasis and in the etiology of hypomagnesemic tetany.

Seizure episodes during open-field tests among Mongolian gerbils fed different combinations of minerals

Tonic-clonic convulsions characteristic of hypomagnesemic tetany were shown with greater frequency during open-field tests among gerbils undergoing simple dietary Mg deficiency than among controls deprived of all minerals. The greater effect from simple Mg deficiency may result from antagonistic activity of other minerral ions. Because seizures in acute hypomagnesemia resemble “spontaneous seizures” of apparently normal gerbils, there is a possibility that the latter animals may be afflicted with chronic hypomagnesemia of the “latent tetany” type owing to an impairment in Mg metabolism.

Blood chemistry as an aid to diagnosis of combined copper and magnesium deficiency in single-suckler calves

Calcium, magnesium, copper, inorganic phosphorus, sodium, potassium, total protein, albumin, globulin, urea, glucose, packed cell volume and haemoglobin in the bloods of apparently health single-suckler calves were frequently measured. Values were within normal ranges except magnesium and copper which became subnormal as lactation advanced and closely approached values of single-suckler calves clinically affected with combined hypomagnesaemic tetany and hypocuprosis which responded to magnesium and copper therapy.

Pathogenesis of theclinical symptoms of hypomagnesaemta in ruminants

Recent investigations of the pathogenesis of hypomagnesaemic tetany have shown that the clinical symptoms are of central origin and particularly related to a reduction in Mg content of the CSF (and probably also the intercellular fluid of the brain). Reduction in the level of plasma Mg is an important feature of these changes, but is not the cause of acute symptoms. The educed level of plasma Ca — often associated with hypomagnesaemia —may modify the clinical picture, but it is not a major feature in the induction of the acute stages. The influence of so-called trigger subctances for the onset of clinical symptoms (ammonia, phosphate, citric acid) could not be confirmed in acute experiments.

A survey of the incidence of deaths from hypomagnesaemic grass tetany and of some management factors possibly related to their occurrence in beef cows in the Wairarapa

Abstract A survey, covering 37.2% of the beef cows in the Masterton and Wairarapa South Counties, of the incidence of deaths from hypomagnesaemic grass tetany and some management factors possibly related to the occurrence of the disorder was carried out for 1972, 1973, and 1974. The number of deaths was greatest in 1974 when the losses represented 2.14% of all beef cows and 4.62% of cows in affected herds. Of the 75 affected herds 44 lost less than 4% of their cows, and 11 lost more than 10% of their cows. Some 45 out of the 154 herds surveyed which had losses in 1974 also lost cows in previous years. Most deaths occurred in mixed-age cows (5.25%), fewer deaths occurring in animals calving for the first time (1.88%). Further, 69.1% of these losses occurred within 3 weeks after parturition. Cows in heavier condition in early winter and before calving appeared to be more prone to hypomagnesaemic grass tetany. The incidence of deaths was reduced on Farms where autumn-saved pasture was fed to the cows at calving and during early lactation.

Plasma and cerebrospinal fluid magnesium, calcium and potassium concentrations in dairy cows with hypomagnesaemic tetany.

Abstract Extract Although grass tetany is invariably associated with hypomagnesaemia, it is widely recognized that hypomagnesaemia per se is not sufficient to induce the signs.

Grass Tetany: An Hypothesis Concerning its Relationship with Ammonium Nutrition of Spring Grasses

An hypothesis suggests that grass tetany is caused by the peculiar growing conditions during early spring resulting in unique compositional characteristics of spring forages. Winter leaching, low soil temperatures, and application of ammonium containing fertilizers make the ammonium ion the principal source of nitrogen available to the plant during this period. Absorption of ammonium by the plant results in greatly reduced uptake of magnesium and calcium with little effect on potassium and produces high amide concentration in the plant with depletion of carbohydrates. These factors combine in the animal to create a high concentration in the rumen of free ammonia and an increased pH, depletion of the remaining carbohydrate, and a further reduction in the availability of the already low magnesium and calcium. When these factors are expressed, they result in low magnesium in blood serum and interact to produce hypomagnesemic tetany in the animal.