Topic:Magnesium
Magnesium is an essential mineral involved in numerous physiological processes in horses, including nerve function, muscle contraction, and bone integrity. It is a component of many enzymes and is necessary for energy metabolism and the synthesis of nucleic acids and proteins. Magnesium levels in horses can be influenced by dietary intake, absorption efficiency, and overall health status. Deficiencies or imbalances may affect neuromuscular function and metabolic processes. This page compiles peer-reviewed research studies and scholarly articles that explore the role, metabolism, and dietary requirements of magnesium in equine health, as well as its impact on performance and disease management.
Salt consumption and the effect of salt on mineral metabolism in horses. The voluntary salt consumption of mature unexercised horses was measured weekly for up to 45 weeks. Voluntary intake among horses was quite variable ranging from 19 to 143 g of salt per day and was inversely related to total salt intake (salt in feeds plus voluntary intake). Mean daily voluntary salt consumption was 53 g. Season of the year did not influence voluntary intake. In preference tests which evaluated every two choice combination of 0.2% and 4% NaCl in test diets fed daily for four days, ponies generally preferred diets containing the lower amount of salt. In similar preference studi...
Complement-mediated hemolysis of horse erythrocytes treated with equine infectious anemia virus. Horse erythrocytes treated with equine infectious anemia virus hemagglutinin were found to be lysed after incubation with fresh horse serum at 37 degrees C. Fresh guinea pig serum induced more efficient hemolysis than horse serum. Direct immunofluorescence test revealed the adsorption of complement factors on the surface of the erythrocytes. Calcium and magnesium ions were necessary for the hemolysis to take place. Antibody against equine infectious anemia virus enhanced the virus-induced complement-mediated hemolysis. These observations indicated that the classical pathway of complement activ...
Lactation in the horse: the mineral composition of mare milk. Changes in the mineral composition of mare milk during lactation were studied. Milk samples were obtained from five Thoroughbred mares one to three times weekly from the first to the eighth week of lactation and from two of the mares for an additional 8 wk. Samples averaging 500 mL were obtained after oxytocin was administered to the mares. Each sample was analyzed for total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper and zinc. The concentration of all constituents except sodium and potassium decreased throughout lactation. The rates of decline of ash, calcium, phosp...
Kidney function in rats with corticomedullary nephrocalcinosis: effects of alterations in dietary calcium and magnesium. Single-nephron and whole-kidney function were studied in female rats with corticomedullary nephrocalcinosis, and in animals where the lesion had been prevented either by a dietary magnesium supplement or by using a diet with a calcium:phosphorus ratio in excess of 1. At the single-nephron level, rats with nephrocalcinosis had prolonged tubular fluid transit times. Proximal transit time was 19.42 +/- 1.98 (mean +/- S.E. of mean) vs. 11.58 +/- 0.19 s for controls; distal transit time was 62.64 +/- 9.16 vs. 31.50 +/- 1.03 s for controls. Although single-nephron function is altered in nephrocalcin...
Digestion in horses after resection or ischemic insult of the large colon. The effect of 60% resection of the large colon vs ischemic insult without resection on the ability of horses to digest grass hay was investigated. Digestion trials were performed on 9 horses before surgery (base line) and 3 weeks, 6 weeks, and 6 months after surgery. The percentage of apparent digestion of crude protein, crude fiber, nitrogen-free extract, calcium, phosphorus, magnesium, manganese, copper, and zinc was calculated. Horses that had resection (n = 5) had decreased apparent digestion of crude protein, crude fiber, and phosphorus 3 weeks after surgery, compared with those in horses...
Metabolism of some essential minerals in ponies fed high levels of aluminum. The effect of dietary aluminum on the absorption, retention and pathways of excretion of calcium, phosphorus, magnesium, zinc, iron and copper was studied in balance trials in mature ponies in a three by three latin square experiment. A basal diet consisting of one third each of oats, beet pulp and a commercial pelleted, complete horse ration and containing 336 ppm aluminum was supplemented with AlC1(3) . 6H2O. The middle and high level aluminum diets contained 1370 and 4500 ppm aluminum respectively. There was little difference in effect between the middle level aluminum and basal diets. The ...
Lysosomal arylsulfatases A and B from horse blood leukocytes: purification and physico-chemical properties. Lysosomal arylsulfatases A and B (aryl-sulfate sulfohydrolases, EC 3.1.6.1) from horse leukocytes were purified about 680-fold and 70-fold, respectively, starting from a crude extract of the azurophil and specific granules of leukocytes, by affinity, ion exchange, and gel filtration chromatography. Purified arylsulfatase A displayed anomalous kinetics, a pH optimum at 5.2, an isoelectric point at 4.3, and a Km value for p-nitrocatechol sulfate (pNCS) of 0.37 mM. This enzyme was found to exist in two association states depending on pH: a high molecular weight form at pH 5.0 and a low molecular ...
A comparison of the mineral composition of milk of domestic and captive wild equids (Equus przewalski, E. zebra, E. burchelli, E. caballus, E. assinus). Milk samples were obtained in early and/or late lactation from Przewalski horses, Hartmann's zebras, Grant's zebras, domestic horses, ponies and a mule mare made pregnant by embryo transfer. Samples were compared for their content of total solids, ash, calcium, phosphorus, magnesium, sodium, potassium, copper, zinc and iron. Milk from the Przewalski horses, Hartmann's zebra and the domestic horse had similar mineral composition and the content of minerals was higher in early than in late lactation. Milk from the domestic mule contained the lowest concentration of calcium, phosphorus and zinc b...
Methods of assigning accurate values to reference serum. Part 2. The use of definitive methods, reference laboratories, transferred values and consensus values. Eight analytes (Ca, Cl, cholesterol, glucose, Mg, K, Na and urate) have been determined in one horse serum masterlot by up to six different procedures: (i) by so-called definitive methods; (ii) by a group of reference laboratories using a variety of analytical methods; (iii) using the results of two independent external quality assessment schemes; (iv) by transferring values from a human serum standard reference material analysed by definitive methods; (v) by similar transfer of values from several batches of horse reference serum previously analysed by definitive methods; and (vi) as in (v) b...
Three-year study on trace mineral concentration in the blood plasma of Shetland pony mares. Changes in some trace minerals concentrations (calcium, inorganic phosphorus, magnesium, zinc, iron, copper, sodium and potassium) in blood plasma were investigated during a three-year period in Shetland pony mares. Blood plasma mineral concentrations were determined by the atomic absorption method and colorimetric method. The three-year averages were in micrograms/ml; Na 4630 +/- 168; K 277 +/- 3.8; Ca 171 +/- 3.8; P 31.5 +/- 0.74; Fe 1.92 +/- 0.14; Zn 1.07 +/- 0.04 and Cu 1.06 +/- 0.02. Two trace minerals (magnesium in inorganic phosphorus) showed only long-term tendency changes--upward or d...
Some nutritional aspects of colic in horses. Consistency of exercise and diet are important in colic prevention. Water should be offered before and after feeding. Fast-growing foals suckling heavily lactating mares may overeat grain at weaning. Creep feeding to accustom the foal to eating grain and gradually increasing the grain intake after weaning are helpful in preventing colic in foals. Stallions may overeat grain when taken off pasture in hot weather. Feeding hay initially and grain later helps avoid colic in these stallions. Type-D Clostridium perfringens may cause enterotoxemia in foals. Corn should be fed in moderation. High-Mg d...
Interrelationships of constituents and partition of salts in milk samples from eight species. Skim-milk samples from rat, rabbit, pig, sheep, goat, horse and man were analysed for lactose, casein and the total and ultrafilterable concentrations of the main salts. Results are compared with data for the cow. The ultrafiltrate concentrations of Ca and Mg were positively correlated with that of citrate and the colloidal concentrations of Ca, Mg and citrate were positively correlated with that of Pi, suggesting that common, general, principles determine the partition of salts in milks. Casein concentration in the skim-milks was inversely related to that of lactose in accordance with a recen...
Composition of sweat of the horse during prolonged epinephrine (adrenaline) infusion, heat exposure, and exercise. Temporal changes in sweat composition were studied in 4 horses during epinephrine (adrenaline) infusion (0.13 to 0.31 micrograms/kg/min for 3 hours), heat exposure (41 C, [33 C wet bulb] for 5 to 6 hours), and exercise (16 to 18 km/hr for 58 to 80 km). Four ponies also were studied during heat exposure. Sweat produced by each of the stimuli was hypertonic for Na+, K+, and Cl-. These electrolyte concentrations remained constant during the central period of the experiments, with changes occurring near the beginning and toward the end. The Na+ was significantly higher and K+ significantly lower i...
Biochemical and haematological effects of phenylbutazone in horses. Five matched pairs of horses were used to investigate the effects of phenylbutazone on a range of physiological, biochemical and haematological variables. The drug was given by mouth daily for 15 consecutive days at the manufacturer's recommended dose rates to one group of horses (Group A); the second group (Group B) received equivalent doses of a placebo. For some of the measured parameters, significant changes were recorded in both groups, indicating background instability. Significant decreases in serum total protein, albumin, plasma pH, viscosity and magnesium, and an increase in albumin: ...
[Experimental reproduction of lactic acidosis in the pony]. One pony has been subjected to the intravenous injections of L-lactic acid. Two other ponies have been trained to intracaecal administration of L-lactic acid or sucrose. The obtained results show that: Intravenous injection of lactic acid increases the concentration of histamin and lactic acid, decreases the level of magnesium and reduces the pressure of carbon dioxide in the blood (the control animals and the treated animals) without the clinical symptoms of lactic acidosis. Intracaecal administration of lactic acid induces a high liberation of histamin in the caecum (the control animals and ...
[Two cases of tetany in the horse (author’s transl)]. Two cases of tetany in the horse are reported. The two patients were thoroughbreds. One was eight and the other thirteen years old. The mares were in heat and were brought to the service (stud) station to be mated. Both patients were nursing a foal. One was a four-week-old foal and the other was seven weeks old. The calcium level of the serum had dropped in the two patients, to 4.0 mg and 5.4 per ml. respectively. The magnesium level was 1.0 mg and 1.9 mg per 100 ml. respectively. The animals responded satisfactorily to intravenous infusion of calcium borogluconate and magnesium chloride. One ...
Acute vitamin D2 (ergocalciferol) toxicosis in horses: case report and experimental studies. Acute accidental vitamin D2 (ergocalciferol) toxicosis was diagnosed in a 6-month-old foal with extensive lesions of soft tissue mineralization. In an experimental study, three 18-month-old horses were given ergocalciferol per os at a rate of 9,300, 22,200, or 47,200 IU/kg of body weight/day for 21 days. Clinical signs or lesions were not seen in horses given the low and intermediate doses, whereas the horse receiving the highest dose developed clinical signs and lesions similar to those noted in the foal. Signs included depression, loss of appetite, weakness, limb stiffness with impaired mobi...
Environmental zinc and cadmium pollution associated with generalized osteochondrosis, osteoporosis, and nephrocalcinosis in horses. Several suspect causes of chronic zinc/cadmium toxicosis in horses near a zinc smelter were investigated following observations of lameness, swollen joints, and unthriftiness, particularly in foals. Two foals born and raised near the smelter were lame and had joint swellings that were attributable to severe generalized osteochondrosis. Zinc and cadmium concentrations were markedly increased in the pancreas, liver, and kidney. The serum of 1 foal, zinc and potassium concentrations were high, whereas calcium and magnesium concentrations were low. Marked nephrocalcinosis and osteoporosis were obs...
The interaction of equine platelet tropomyosin with skeletal muscle actin. Whereas skeletal muscle tropomyosin binds strongly to muscle F-actin in a buffer containing 30 mM KCl and 1-2 mM free Mg2+, equine platelet tropomyosin only binds stoichiometrically (1 tropomyosin molecule per 6 actin monomers) at higher Mg2+ concentrations (7-8 mM free Mg2+). At low free Mg2+ concentrations (1.5 mM) the binding of the platelet protein is only marginally increased by raising the KCl concentration to an optimal value (0.10-0.20 M). This weaker binding can be attributed to the relatively poor head-to-tail polymerization of platelet tropomyosin and its fewer actin-binding sites. ...
Clinical and structural features of equine enteroliths. Enteroliths were obtained by laparotomy or necropsy of 11 horses, and a collection of smaller concretions was found on pasture. Following analysis by energy-dispersion x-ray analysis and x-ray diffraction, they were found to consist primarily of ammonium magnesium phosphate. Several minor elements were detected, including titanium in some concretions. From a farm with a history of enterolith obstructions, the well water contained a high proportion of magnesium in relation to the other cations.
[Circadian variations in the content of plasma constituants in the brood mare]. Twenty-one circadian blood sample profiles were made in heavy brood mares during pregnancy, lactation or the dry, non-pregnant period. The mares were fed forage-rich diets containing different levels of energy and nitrogen (table 1). Each profile consisted of 7 samples taken at 8 a.m., 11 a.m., 3 p.m., 7 p.m., 11 p.m., 4 a.m. and 8 a.m. The animals were fed at 8:30 a.m. The eleven plasma components evaluated were glucose, non-esterified fatty acids, beta-hydroxybutyrate, acetate, alanine, insulin (energy metabolites), urea, total protein (nitrogen metabolites), calcium, inorganic phosphorus an...
[Variations in plasma components in lactating mares at late pregnancy-early lactation (author’s transl)]. In an experiment comparing pregnant then lactating mares with dry non-pregnant mares, the changes in plasma components were studied as indicators of the metabolic utilization of energy (glucose, non-esterified fatty acids, beta-hydroxybutyrate), nitrogen (urea, proteins) or minerals (calcium, phosphorus, magnesium). The mares were fed daily 2 kg concentrate and hay ad libitum. Beta-hydroxybutyrate, magnesium and to a lesser extent glucose were the only constituents whose levels were affected within the period starting one month before and ending one month after foaling. The increase in food in...
Influence of exercise on serum selenium and peroxide reduction system of racing Standardbreds. Blood samples were obtained from 45 racing Standardbred horses immediately before and immediately after a training jog at a commercial race track to establish reference values for serum selenium and related values of the peroxide reduction system of racing horses. Hemoglobin, hematocrit, and serum selenium increased significantly (P < 0.001), whereas RBC-reduced glutathione decreased significantly (P < 0.01) immediately after exercise. Glutathione peroxidase and glutathione reductase were not altered by exercise. Serum copper and magnesium were significantly increased (P < 0.01) after exercise...
Water hardness in relation to cadium accumulation and microscopic signs of cardiovascular disease in horses. The hardness of drinking water (i.e., the sum of calcium and magnesium concentrations) has been related to cadmium concentration in kidney cortex and to microscopic signs of arteriosclerosis and focal myocardial fibrosis in 50 Swedish horses slaughtered for meat production. A significant negative correlation was found between water hardness and cadmium concentrations in kidney cortex. This indicates that horses living in soft water areas are more inclined to accumulate cadmium from the general environment. Microscopic changes in the aorta and myocardium were approximately 2 times as frequent i...
Cannulation of the equine oviduct and chemical analysis of oviduct fluid. Siliconized rubber tubes were used to cannulate one oviduct in 7 mares, and secretions were collected in a polycarbonate container located externally, in the region of the left paralumbar fossa. Secretion rates were recorded daily during the estrous cycle. Concentrations of calcium, magnesium, sodium, potassium, inorganic phosphorus and glucose were determined in the oviduct fluids secreted throughout the estrous cycle. Secretion rates were greatest during estrus (days 1-9), with a significant decrease (P<.01) noted during nonestrus (days 10-21). Concentrations of all constitutents measured...
Hematological and biochemical values of thoroughbred foals in the first six months of life. Hematological and biochemical parameters in five Thoroughbred foals during the first six months of life are reported. The samples were analyzed for red blood cell, packed cell volume, hemoglobin, platelet, white blood cell, absolute number for leukocytes, and erythrocyte fragility and serum calcium, inorganic phosphorus, sodium, potassium, chloride, magnesium, alkaline phosphatase, icterus index unit, bilirubin, blood urea nitrogen, nonprotein nitrogen, blood glucose, lacticdehydrogenase, glutamic pyruvic transaminase, glutamic oxalacetic transaminase, total protein, albumin, globulin, and A/G...
Changes in mammary development and composition of secretion during late pregnancy in the mare. Small samples of mammary secretion were taken for analysis from Thoroughbred mares during the last 3 weeks of pregnancy up to the time of foaling. The concentrations of sodium and chloride decreased while those of lactose, potassium, citrate, phosphate, calcium, magnesium and protein increased. The time-course of these changes showed marked variation between animals. The concentration of whey proteins began to increase about 10 days before parturition. The appearance of the secretion and the size of the mammary glands increased in the last few days of pregnancy. It is suggested that the concen...