Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Calcium
Calcium is a mineral that is essential for various physiological processes in horses, including bone development, muscle function, and nerve transmission. It is a critical component of the equine diet and is involved in maintaining skeletal integrity and supporting metabolic functions. Calcium levels in horses are regulated through dietary intake, absorption in the gastrointestinal tract, and hormonal control mechanisms involving the parathyroid hormone and vitamin D. Imbalances in calcium levels can lead to health issues such as metabolic bone disease or hypocalcemia. This page compiles peer-reviewed research studies and scholarly articles that explore the metabolism, dietary requirements, and health implications of calcium in equine nutrition and physiology.
Infrared and atomic spectrometry analysis of the mineral composition of a series of equine sabulous material samples and urinary calculi. Atomic spectrometry has been used in 20 samples of equine urinary sabulous deposits in order to detect minor elements accompanying the predominant element, calcium, which is present in the form of calcium carbonate (calcite and/or vaterite). The elements measured have been (besides calcium) magnesium, sodium, potassium, iron, copper and manganese. Phosphates, sulphates and silica are frequently present as minor constituents of equine urinary sabulous deposits and uroliths, but their detection can be difficult by infrared (IR) spectroscopy in the original samples due to overlapping with the ban...
Redox regulation of large conductance Ca(2+)-activated K+ channels in smooth muscle cells. The effects of sulfhydryl reduction/oxidation on the gating of large-conductance, Ca(2+)-activated K+ (maxi-K) channels were examined in excised patches from tracheal myocytes. Channel activity was modified by sulfhydryl redox agents applied to the cytosolic surface, but not the extracellular surface, of membrane patches. Sulfhydryl reducing agents dithiothreitol, beta-mercaptoethanol, and GSH augmented, whereas sulfhydryl oxidizing agents diamide, thimerosal, and 2,2'-dithiodipyridine inhibited, channel activity in a concentration-dependent manner. Channel stimulation by reduction and inhibit...
Digestibility, apparent mineral absorption, and voluntary intake by horses fed alfalfa, tall fescue, and caucasian bluestem. Alfalfa (Medicago sativa L.), low-endophyte (< 5%) tall fescue (Festuca arundinacea Schreb.), and caucasian bluestem (Bothriochloa caucasica [Trin.] C.E. Hubbard) were fed as chopped hay to six Arabian geldings (BW 441 kg; SE 2) in intake and digestibility experiments to determine nutritional value for horses at maintenance. Each experimental design was a replicated Latin square. Alfalfa was higher in DM and CP digestibility, IVDMD, apparent absorption of Ca, K, and S, and voluntary intake than the grasses (P < .05). Caucasian bluestem was higher in Zn but was lower in CP, TNC, Mg, P, K,...
Fetal calcium homeostasis. The mammalian fetus is maintained hypercalcaemic relative to its mother primarily by the action of a placental calcium pump located in the basal plasma membrane of the trophoblast. It is suggested that the activity of this pump is stimulated by a mid-molecular fragment of parathyroid hormone-related protein [PTHrP(38-94NH2)], produced in the placenta (and also in the parathyroid glands of fetal lambs and calves) as a result of post translational processing. In the sheep, calcitriol is an important determinant of fetal calcium homeostasis and it, too, stimulates the transport of calcium across ...
Structural characterisation and comparison of the native and A-states of equine lysozyme. Native state 1H NMR resonance assignments for 125 of the 129 residues of equine lysozyme have enabled measurement of the hydrogen exchange kinetics for over 60 backbone amide and three tryptophan indole hydrogen atoms in the native state. Native holo equine lysozyme hydrogen exchange protection factors are as large as 10(6), the most protected residues being located in elements of secondary structure. High exchange protection in the domain interface correlates with the binding of Ca2+ in this region. Equine lysozyme differs from most non-Ca2+ binding lysozymes in forming a highly populated par...
The relationship between the concentration of ionised calcium and parathyroid hormone-related protein (PTHrP[1-34]) in the milk of mares. Once lactation is established in mares, there is little change in the ionised calcium concentration in their milk. In contrast, the concentration of PTHrP(1-34) in the milk increases to a maximum level by the end of the second week of lactation, near which it remains for the rest of the lactation. As found in other species, the concentration of PTHrP(1-34) in mare's milk is considerably higher than that in plasma, sampled at the same time. No significant correlation could be demonstrated between the concentrations of PTHrP(1-34) and ionised calcium in the milk except during the last 10 weeks o...
Membrane contact with oviductal epithelium modulates the intracellular calcium concentration of equine spermatozoa in vitro. Interaction of equine spermatozoa with oviductal epithelial cells (OEC) prolongs sperm viability and maintains low intracellular calcium concentration ([Ca2+]i) in spermatozoa. Experiments were designed to investigate 1) whether release of spermatozoa from OEC in vitro is associated with elevated [Ca2+]i and 2) whether soluble products from OEC or direct membrane contact between spermatozoa and OEC mediates the effects of OEC on sperm [Ca2+]i. In the first experiment, changes in [Ca2+]i in spermatozoa loaded with indo-1 acetoxymethylester were determined in motile spermatozoa released from OEC...
Multi-element assay of mammary secretions and sera from periparturient mares by inductively coupled argon plasma emission spectroscopy. To document and determine changes in the mineral profiles of sera and mammary secretions from a population of periparturient mares. Methods: 18 clinically normal periparturient Arabian broodmares. Methods: Inductively coupled argon emission spectroscopy was used to measure Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn concentrations in sera and mammary secretions of periparturient mares. In addition, S was measured in mammary secretions. Results: Serum concentrations of Ca, Cu, Fe, K, Mg, Na, P, and Zn remained constant throughout late pregnancy and the first 7 days of lactation. Compared with values o...
Methods for the isolation, culture and characterisation of equine pulmonary artery endothelial cells. Equine endothelial cells were isolated from the pulmonary artery by enzymatic digestion and grown to confluency. The cells were characterised by positive immunofluorescent staining for von Willebrand factor and NADPH-diaphorase staining for nitric oxide synthase. Measurements of endothelins indicated that there were significant release rates from the cells for up to six hours. Measurements of intracellular calcium concentration showed that the application of bradykinin caused a transient increase in calcium concentration with similar characteristics to those observed in other endothelial cell ...
Preileal digestibility of coconut fat and soybean oil in horses and their influence on metabolites of microbial origin of the proximal digestive tract. Three horses (approximately 190 kg BW) fitted with a permanent fistula at the end of the jejunum were used. To a control diet (1/3 hay, 2/3 mixed feed) one of two fat types (coconut fat or soybean oil) were added at 2 levels resulting in fat intakes of 0.1 g (control diet) to 0.5 or 1 g/kg BW 0.5 d, respectively. Each experimental period consisted of 2 weeks adaptation, 2 days of breath tests (before and hourly after the morning meal) and 5 days sampling of chyme. Crude fat, crude protein, concentrations of organic acids (SCFA, lactic acid), pH, and the minerals calcium, magnesium and phosphor...
[Course of blood levels of calcium, inorganic phosphate, alkaline phosphatase, parathyroid hormone and calcidiol (25-OH-D3) in one and two year old thoroughbred horses]. The present study was aimed to determine the contents of calcium, inorganic phosphate, parathormon, 25-OH-D3 and the activity of alkaline phosphatase in the plasma of one- and two-years-old thoroughbred horses. Data were obtained monthly from 44 one-year-old thoroughbred of 4 different studs from May during grazing-season and from October during stable-, resp. training-season up to april of the following year. Calcium, inorganic phosphate and the activity of alkaline phosphatase were measured with a photometric method and the concentration of PTH and 25-OH-D3 were determined with a radioimmuno...
Anion secretion induced by capacitative Ca2+ entry through apical and basolateral membranes of cultured equine sweat gland epithelium. 1. Anion secretion induced by capacitative Ca2+ entry through apical and basolateral membranes of cultured equine sweat gland epithelium was studied using the short-circuit current (Isc) technique. 2. Thapsigargin induced an increase in Isc that could be inhibited when external Ca2+ was chelated by EGTA. 3. The inhibition of the thapsigargin-induced Isc could be reversed by re-addition of Ca2+ to apical or basolateral solutions. The magnitude of the reactivated Isc depended predominantly on basolateral Ca2+ concentration. 4. The magnitude of the reactivated Isc upon basolateral Ca2+ addition i...
Hemodynamic effects of calcium gluconate administered to conscious horses. Calcium gluconate was administered to conscious horses at 3 different rates (0.1, 0.2, and 0.4 mg/kg/min for 15 minutes each). Serum calcium concentrations and parameters of cardiovascular function were evaluated. All 3 calcium administration rates caused marked increases in both ionized and total calcium concentrations, cardiac index, stroke index, and cardiac contractility (dP/dtmax). Mean arterial pressure and right atrial pressure were unchanged; heart rate decreased markedly during calcium administration. Ionized calcium concentration remained between 54% and 57% of total calcium concentr...
Use of peanut agglutinin to assess the acrosomal status and the zona pellucida-induced acrosome reaction in stallion spermatozoa. Peanut agglutinin (PNA) was used to assess the sperm acrosomal status and the acrosome reaction during gamete interaction in the equine species. PNA exclusively binds to the outer acrosomal membrane of stallion spermatozoa, as was established by transmission electron microscopy. Fluorescein isothiocyanate-PNA (FITC-PNA) labeling was used to monitor sperm acrosomal changes during a prolonged incubation period of 24 hours and during a 2-hours incubation in the presence of 5 microM calcium ionophore A23187. In addition, after a 4-hours preincubation in SP-TALP medium, sperm samples were incubated...
Activation of apical P2U purine receptors permits inhibition of adrenaline-evoked cyclic AMP accumulation in cultured equine sweat gland epithelial cells. Experiments were undertaken using cultured equine sweat gland epithelial cells that express purine receptors belonging to the P2U subclass which allow the selective agonist uridine triphosphate (UTP) to increase the concentration of intracellular free Ca2+ ([Ca2+]i). Experiments using pertussis toxin (Ptx), which inactivates certain guanine-nucleotide-binding proteins (G-proteins), showed that this response consisted of Ptx-sensitive and Ptx-resistant components, and immunochemical analyses of the G-protein alpha subunits present in the cells showed that both Ptx-sensitive (alpha i1-3) and Ptx...
Daily fluctuations of haematology and blood biochemistry in horses fed varying levels of protein. Changes in the plasma biochemistry of 12 stallions were studied over seven 24 h periods. Twelve healthy male horses of 4 different breeds (Thoroughbred [TB], Anglo-Arabo-Sardo [AAS], Avelignese [Av] and Maremmano [M]) were divided into 3 experimental groups and fed with an isoenergetic maintenance ration with different protein levels. The same amount of food was given daily at 0730 and 1930 h. After 20 days of pretrial, a series of 6 blood samples were collected daily from the jugular vein every 4 h for 7 days. The samples were analysed for packed cell volume (PCV), haemoglobin, plasma glucose...
Calcium buffering is required to maintain bone stiffness in saline solution. This work determined whether mineral dissolution due to prolonged testing or storage of bone specimens in normal saline would alter their elastic modulus. In one experiment, small pieces of equine third metacarpal bone were soaked in normal saline supplemented with varying amounts of CaCl2. Changing Ca ion concentrations in the bath were monitored and the equilibrium concentration was determined. In a second experiment, the elastic moduli of twenty 4 x 10 x 100 mm equine third metacarpal beams were determined non-destructively in four-point bending. Half the beams were then soaked for 10 days ...
Restoration of water and electrolyte balance in horses after repeated exercise in hot and humid conditions. Nine adult riding horses performed on a treadmill a competition exercise test (CET) and 24 h later a standardised exercise test (SET) at mean temperature 28 degrees C and relative humidity 58%. Each horse performed the tests 5 times at 2 week intervals. The horses were given isotonic glucose-electrolyte solution via a nasogastric tube 30 min after the CET, except after the last trial when water was given. Blood lactate, plasma concentration of aldosterone, arginine vasopressin, protein, sodium, potassium, chloride, magnesium and calcium were measured. Heart rate at blood lactate concentration ...
Biochemical changes in three-day-event horses at the beginning, middle and end of Phase C and after Phase D. Blood samples were collected 12-16 h before the Speed and Endurance test, immediately after steeplechase, midway through Phase C (4 km marker), at the end of Phase C and immediately after cross-country from 36 horses that completed a 3-day-event at the CCI* (n = 19) or CCI** (n = 17) level. Packed cell volume (PCV), plasma concentrations of sodium, potassium, chloride, ionized calcium, pH and lactate; and serum concentrations of total protein (TP), albumin, total calcium, alkaline phosphatase (AP), gamma glutamyl transferase (GGT), creatine kinase (CK), aspartate aminotransferase (AST), glucos...
Elemental composition of muscle at rest and potassium levels in muscle, plasma and sweat of horses exercising at 20 degrees C and 35 degrees C. In this study, 4 Standardbred geldings were exercised at 20 and 35 degrees C. The exercise test (ET) consisted of 2 exercise bouts separated by 2 h of rest in their boxes. Blood samples were taken before, during and after the second exercise bout and muscle (m. gluteus medius) biopsies were taken before the first exercise bout and after an intensive trot over 2600 m in the second exercise bout. The blood samples were analysed for plasma potassium and total plasma protein concentration (TPP) and the muscle fibres were analysed for elemental composition by x-ray microanalysis. The intracellular ...
Ionic mechanisms of Ca(2+)-dependent electrolyte transport across equine sweat gland epithelium. 1. The ionic mechanism involved in Ca(2+)-stimulated electrolyte transport in cultured equine sweat gland epithelial cells was studied using the short-circuit current (ISC) technique. 2. Microscopy revealed that the cultured cells grown on Millipore filters formed polarized monolayers with tight junctions. Monolayers exhibited a mean transepithelial resistance of 333.9 +/- 40.4 omega cm2. 3. Ca(2+)-mobilizing agents, A23187 (1 microM) or thapsigargin (0.01-1 microM), stimulated ISC while forskolin exerted little effect on the ISC. 4. Replacement of external Cl- by gluconate significantly reduc...
Use of adverse conditions to stimulate a cellular stress response by equine articular chondrocytes. To determine the response of equine articular cartilage cells to heat and calcium stresses. Methods: Analysis of newly synthesized, [35S]methionine-labeled proteins after treatment of isolated primary equine chondrocytes. Methods: Primary cultures of equine articular chondrocytes were incubated at temperatures ranging from 37 to 42 C for heat stress experiments or incubated in the presence or absence of the intracellular calcium pump inhibitor, thapsigargin, for calcium stress experiments. Patterns of new protein synthesis were determined by incubating with [35S]methionine followed by separati...
Hyperkalemic periodic paralysis episode during halothane anesthesia in a horse. A 7-month-old Quarter Horse filly was admitted for surgical repair of a right olecranon fracture. Anesthesia was achieved with xylazine hydrochloride, guaifenesin, ketamine hydrochloride, and halothane. Two and a half hours after induction of anesthesia, myotonia, muscle fasciculations, and sweating, concurrent with high serum potassium concentration and associated electrocardiographic changes consistent with hyperkalemic periodic paralysis, were observed. Treatment included intermittent positive-pressure ventilation, changing intravenous administration of fluids from lactated Ringer's solutio...
Minor constituents of sabulous material in equine urine. The secondary constituents accompanying calcite and vaterite (crystalline forms of calcium carbonate) in the sabulous deposits from 140 vesical samples and one renal sample of equine urine were studied by infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). Apatitic calcium phosphate, present in 12 per cent of the samples, generally appeared in the form of spherulites with smooth and rough surfaces. Calcium sulphate, clearly detected by IR in 12.7 per cent of the samples, did not have a characteristic structure under SEM, although EDX detec...
Voltage-dependent calcium currents and cytosolic calcium in equine airway myocytes. 1. The relationship between voltage-dependent calcium channel current (I(Ca)) and cytosolic free calcium concentration ([Ca2+]i) was studied in fura-2 AM-loaded equine tracheal myocytes at 35 degrees C and 1.8 mM Ca2+ using the nystatin patch clamp method. The average cytosolic calcium buffering constant was 77 +/- 3 (n = 14), and the endogenous calcium buffering constant component is likely to be between 15 and 50. 2. I(Ca) did not evoke significant calcium-induced calcium release (CICR) since (i)[Ca2+]i scaled with the integrated I(Ca) over the full voltage range of evoked calcium currents, ...
[Kidney function tests in horses–methods and reference values in healthy animals]. Investigations of renal function have been done on the basis of renal clearance (Clr) and excretion (E) of endogenous creatinine in healthy horses of different body weight (23 female, 7 male). Creatinine was measured by enzymatic PAP-method. Creatinine-E of female horses was poor positively correlated with body weight. The creatinine-Clr was highly correlated with the inulin-Clr (r = 0,896, p < 0,001). The excretion of creatinine was 35% higher than the filtration of creatinine, determined by inulin-Clr. That demonstrate a tubular net secretion of 26% of the total creatinine excretion. Howe...
Intracellular calcium concentration in equine spermatozoa attached to oviductal epithelial cells in vitro. Interaction of spermatozoa with oviductal epithelial cells (OEC) in the oviductal isthmus prolongs the life span of spermatozoa. The hypothesis that the interaction of equine spermatozoa with OEC affects their intracellular calcium concentration ([Ca2+]i) was tested in a sperm-OEC coculture model. Changes in [Ca2+]i in spermatozoa loaded with the fluorescent calcium indicator indo-1 acetoxymethylester (AM) were determined for spermatozoa attached to OEC or to Matrigel, as well as for free-swimming spermatozoa incubated without oviductal epithelium. [Ca2+]i was determined before incubation and ...
Calcium decreases and parathyroid hormone increases in serum of periparturient mares. Changes in serum concentrations of Ca and parathyroid hormone (PTH) may develop in periparturient mares, may be influenced by dietary Ca, and may be associated with changes in Ca concentration of mammary secretion. Milk and blood samples were taken from eight mares on Farm A and eight on Farm B for 10 d before parturition and from four mares on each farm for 5 d postpartum. Milk Ca was measured by two commercial tests. Serum samples were analyzed for PTH and total Ca in 16 mares and for ionized Ca in six (Farm A). Parturition was induced in eight mares on Farm A and four on Farm B; no signific...
Spontaneous vascular mineralization in the brain of horses. Cerebral vascular mineralization was found in 12 (60%) of 20 3- to 10-year-old healthy horses collected at an abattoir. It was variable in degree and occurred mostly in the pallidal arteries showing two types of lesions; small globoid bodies along capillaries, and amorphous deposits in the wall of arterioles, small- or medium-sized arteries and veins. Both types were strongly positive for periodic acid-Schiff reaction, and weakly positive for von Kossa's and Berlin blue stains. Elemental analysis of the deposit revealed the presence of large amounts of aluminum, moderate amounts of phosphorus,...
Effects of storage on serum ionized calcium and pH from horses with normal and abnormal ionized calcium concentrations. It has been previously shown that Ca(I) concentration is stable in serum collected from healthy horses for 10 days if stored at 40 degrees C. This may not be true for horses with abnormal Ca(I) concentrations. Thus the stability of ionized calcium (Ca(I)) concentration and pH measurement in serum from horses with both normal and abnormal Ca(I) concentrations stored for various times at 40 degrees C and -10 degrees C was evaluated. Our results indicated that serum Ca(I) concentration was stable throughout 7 days of cold or frozen storage, after being received by the Clinical Chemistry Laborator...
