Decrease In Mg Concentration Research Articles

Magnesium absorption, translocation, subcellular distribution and chemical forms in citrus seedlings.

Magnesium (Mg) is an essential macronutrient for plant growth and development; however, the adaptive mechanisms of Mg deficiency to underlying changes in Mg translocation, subcellular distribution and chemical forms in citrus plants are unknown. In this study, we conducted a sand culture experiment with 0 (Mg-deficiency) or 2 (Mg-sufficiency) mmoll-1Mg2+ treatments to investigate the responses underlying Mg adaptability, as well as the resulting growth and Mg transport features in citrus seedlings [Citrus sinensis (L.) Osbeck cv. 'Xuegan']. We found that Mg-deficiency significantly depressed biomass by 39% in the whole plant and by 66% in branch organs compared with Mg-sufficient conditions, which further resulted in a subsequent decrease in Mg concentration and accumulation with changes in its distribution in different organs and a reduction in root growth. Under Mg-sufficiency, >50% of Mg was sequestered in the soluble fraction and this was reduced by 30% under Mg-deficiency. Furthermore, >70% of Mg existed as inorganic (42%) and water-soluble (31%) forms with high mobility across treatments and organs. Under Mg-deficiency, the proportion of water-soluble Mg was reduced in leaf and increased in root, whereas the proportion of inorganic Mg increased in main stem leaves and decreased in branch leaves and root. However, under Mg-deficiency, the proportion of Mg forms with low mobility, including pectates and proteins, phosphates, oxalates and residues, was increased in leaf and root organs, with the exception of pectate and protein Mg, which was decreased in root. The Mg transfer factor showed that Mg-deficiency improved Mg transport from parent to branch organs, which was related to Mg subcellular distribution and chemical forms. Taken together, our study establishes a defined process to clarify the mechanisms of Mg absorption and translocation and reveals a possible strategy to effectively improve Mg mobility and availability in citrus plants.

Strain hardening behavior and strengthening mechanism in Mg-rich Al–Mg binary alloys subjected to aging treatment

The aging hardening response and tensile strain hardening characteristics of cast Al–Mg alloys with high Mg contents (5–13 wt%) were investigated. Aging hardening became significant when the Mg content was greater than 10 wt%. As the Mg concentration increased in the solid solutionized matrix, the strain hardening rate increased. During aging heat treatments at 423 and 453 K, the strain hardening rate increased as the aging time increased and it increased more rapidly as the Mg content in the alloys increased. The effects of the Mg matrix concentration and the precipitates on the strain hardening characteristics were interpreted using the Kocks-Mecking model. For the solid solutionized alloys, as the Mg matrix concentration increased, the dislocation storage rate (k1) increased, whereas the recovery rate (k2) decreased. For the aged alloys, both k1 and k2 increased with increasing Mg content and aging time. The contributions of the Mg matrix concentration and precipitates to the k1 and k2 values in the aged alloys could be separated. The effect of the precipitates to the k1 and k2 values were more significant than the effect of Mg matrix concentration in the aged alloys. The increase in Mg matrix concentration promoted a transition in the Portevin–Le Chatelier (PLC) effect from type B to type C. After the aging treatment, the type B + C serrations occurred in the Al-10 wt%. Mg alloy due to significant decrease of Mg concentration in the matrix. The critical strain for the onset of PLC increased with increasing Mg matrix concentration and aging time. These results were explained in terms of the concentration of plastic-deformation-induced vacancies involving in the diffusion process of solutess, which may decrease as the Mg matrix concentration and the amount of precipitates increase. After aging, the contribution of solid solution strengthening to yield strength decreased, whereas the contribution of particle strengthening to yield strength greatly increased. The particle strengthening effect accounted for 56.8% of the yield strength in Al-13 wt% Mg alloy.

Synthesis of Intermetallic (Mg1−x,Alx)2Ca by Combinatorial Sputtering

The synthesis–composition–structure relationship in the Mg–Ca–Al system is studied using combinatorial magnetron sputtering. With increasing deposition temperature, a drastic decrease in Mg concentration is obtained. This behavior can be understood based on density functional theory calculations yielding a desorption energy of 1.9 eV/atom for Mg from a hexagonal Mg nanocluster which is far below the desorption energy of Mg from a Mg2Ca nanocluster (3.4 eV/atom) implying desorption of excess Mg during thin film growth at elevated temperatures. Correlative structural and chemical analysis of binary Mg–Ca thin films suggests the formation of hexagonal Mg2Ca (C14 Laves phase) in a wide Mg/Ca range from 1.7 to 2.2, expanding the to date reported stoichiometry range. Pronounced thermally-induced desorption of Mg is utilized to synthesize stoichiometric (Mg1−x,Alx)2Ca thin films by additional co-sputtering of elemental Al, exhibiting a higher desorption energy (6.7 eV/atom) compared to Mg (3.4 eV/atom) from Mg2Ca, which governs its preferred incorporation during synthesis. X-ray diffraction investigations along the chemical gradient suggest the formation of intermetallic C14 (Mg1–x,Alx)2Ca with a critical aluminum concentration of up to 23 at.%. The introduced synthesis strategy, based on the thermally-induced desorption of weakly bonded species, and the preferential incorporation of strongly bonded species, may also be useful for solubility studies of other phases within this ternary system as well as for other intermetallics with weakly bonded alloying constituents.

Protective Performance of Plasma-Enhanced Chemical Vapor-Deposited Ethyl Cyclohexane Coating on Magnesium Alloys

In the present investigation, plasma-polymerized ethyl cyclohexane (ECH) coatings were deposited onto AZ31 and AM50 magnesium (Mg) alloys using plasma-enhanced chemical vapor deposition. The influences of deposition time on the coating formation, surface morphology, chemical composition and electrochemical corrosion behavior were investigated. The coating deposition was confirmed by infrared spectroscopy (FT-IR), and the thickness was measured using a scanning electron microscope. Energy-dispersive x-ray analysis revealed an increase in carbon and a decrease in Mg concentrations as the coating duration was increased. Electrochemical impedance spectroscopy (EIS) results confirmed an improvement in the corrosion resistance of AZ31 and AM50 alloys due to ECH coatings in the presence of a 3.5 wt.% NaCl solution. Further, equivalent circuit curve fitting analysis of the EIS results indicated an increase in charge transfer resistance (Rct) values with longer coating durations. These results confirmed the protecting ability of ECH coatings against corrosive ion attack, which was also substantiated by the surface morphologies after corrosion. Impedance values decreased as the duration of exposure in a NaCl solution increased, and the coating prepared using a 30-min ECH deposition exhibited better protection properties.

Influence of Acidification on Carbonate Sediments of Majuro Atoll, Marshall Islands

Influence of acidification on carbonate sediments in Majuro Atoll, Marshall Islands was studied by chemical and mineralogical methods coupled with synchrotron-based X-ray µ-CT. We found that the lowering of soil pH near the surface layer caused decrease of Mg concentration and increase of porosity of foraminifera (Calcarina spp.) due to the selective dissolution of magnesian calcite in Calcarina spp.test.

Assessing chemical elements balance in patients with hypertension

Aim. To assess the imbalance of the chemical elements in biological substrates in the adult population of Irkutsk suffering from hypertension.Methods. During the work performance, the data of 55 patients with hypertension including 40 women aged 41-66 years and 15 men aged 52-66 years living in the city of Irkutsk were investigated. During the study of the elemental status of patients with hypertension, determination of 25 elements content in the hair was performed. Analysis of the studied samples was conducted in the NGO «Center for Biotic Medicine» laboratory. 7 elements is determined by ion-selective method in the blood: K, Na, Mg, Fe, Cl, Ca, P.Results. Elemental status of patients with hypertension is characterized by a low content of essential elements - Ca (482±31.2 mg/kg), Zn (164±12 mg/kg) and Mg (154±3.3 mg/kg), significantly higher content of Na (553±156 mg/kg) in the hair; decrease in concentration of Mg (0.64±0.04 mmol/l) and Ca (2.01±0.05 mmol/l), increase in Na (149±4 mmol/l) and Cl (119.4±2.8 mmol/l) levels in blood. Increased content of chloride in blood serum, boron in the hair, potassium and lead in the hair (in men), a low content of cobalt in the hair (in men) and zinc (in women) were found; compared with men, in women lower contents of sodium in the blood serum, potassium, aluminum, cadmium and lead in the hair, a higher content of calcium, magnesium, chromium, silicon, vanadium and strontium in the hair were registered; the most pronounced correlation was observed between anthropometric parameters and the level of the chemical elements in biological samples.Conclusion. The result of assessing imbalance of the key elements in the blood is more informative than the data on selected elements, probably because the presence of any imbalance reflects either the complexity of the factor impact or the severity of the deficit or excess of one element, which caused shifts of microelement landscape as a whole.

Nutritional status of winter oilseed rape in cardinal stages of growth as the yield indicator

Nutritional status of the seed crop during its vegetative growth is a tool for a reliable yield prognosis. This approach has been validated for oilseed rape in three 2007/2008, 2008/2009, and 2009/2010 seasons. The field experimental design was: untreated control, NP, NPK, NPKMgS1 (1/3 total MgS rate, spring applied), NPKMgS2 (total rate, autumn), NPKMgS3 (2/3 - autumn, 1/3 - spring). The concentrations of N, P, K, Ca, Mg, Mn, Zn, and Cu were measured in two stages: rosette (whole plant) and flowering (leaves). The yield prognosis was based on path analysis and stepwise regression. The elevated concentration of P, Ca, and Zn in plants at the rosette stage was the early symptom of nutrient imbalance. The Mg concentration in plant leaves at flowering was revealed as the decisive yield predictor. The manner of its management in plant canopy during the yield forming period (YFP) was crucial for the harvested yield. It was documented that each factor leading to increase in Ca but decrease in Mg concentration resulted in yield decrease. The key reason of Mg shortage was its low uptake during the YFP and simultaneous increase in Mn concentration.

Experimental Investigation of the Mg-Nd-Zn Isothermal Section at 300 °C

The Mg-Nd-Zn isothermal section at 300 °C was established in the full composition range using diffusion couples and equilibrated key alloys. Microstructural characterization was carried out using WDS, XRD, and metallographic methods. The homogeneity ranges of the binary and ternary compounds were determined by WDS analysis. Six ternary compounds were observed in the Mg-Nd-Zn system at 300 °C. These are: τ1 (Nd5Mg21+xZn45−x; 0 ≤ x ≤ 4), τ2 (Nd5Mg3+yZn25−y; 0 ≤ y ≤ 1), τ3 (NdMg1+zZn2−z; 0 ≤ z ≤ 0.44), τ4 (Mg40Nd5Zn55), τ5 (Mg22–23.5Nd15.5–17.5Zn59.1–61.8), and τ6 (Nd2(Mg,Zn)23). τ5 was found to have a homogeneity range of 22.0–23.5 atom % Mg, 15.5–17.6 atom % Nd and 59.1–61.8 atom % Zn and τ6 was found to have 54.1–61.3 atom % Mg at a constant Nd of 8.0 atom %. The ternary solubility of Zn in Mg-Nd compounds was found to increase with the decrease in Mg concentration. Accordingly, (Mg41Nd5) was found to have an extended solubility of 3.1 atom % Zn, whereas (Mg3Nd) was found to have 30.0 atom % Zn. MgNd was found to have a complete substitution of Mg by Zn. The maximum solid solubility of Zn in α-Mg was measured as 4.8 atom % Zn.

Phase Equilibria of the Ce-Mg-Zn Ternary System at 300 °C

The isothermal section of the Ce-Mg-Zn system at 300 °C was experimentally established in the full composition range via diffusion multiple/couples and key alloys. Annealed key alloys were used to confirm the phase equilibria obtained by diffusion multiple/couples and to determine the solid solubility ranges. Spot analysis was carried out, using wavelength dispersive X-ray spectroscopy (WDS), to identify the composition of the observed phases. The composition profiles were obtained using WDS line-scans across the diffusion zones. X-ray diffraction (XRD) was performed to identify the phases in the annealed alloys and to confirm the WDS results. Eight ternary compounds, in the Ce-Mg-Zn isothermal section at 300 °C, were observed from 45–80 at.% Zn. These are: τ1 (Ce6Mg3Zn19), τ2 (CeMg29Zn25), τ3 (Ce2Mg3Zn3), τ4 (CeMg3Zn5), τ5 (CeMg7Zn12), τ6 (CeMg2.3−xZn12.8+x; 0 ≤ x ≤ 1.1), τ7 (CeMgZn4) and τ8 (Ce(Mg1−yZny)11; 0.096 ≤ y ≤ 0.43). The ternary solubility of Zn in the Ce-Mg compounds was found to increase with a decrease in Mg concentration. Accordingly, the ternary solid solubility of Zn in CeMg12 and CeMg3 was measured as 5.6 and 28.4 at.% Zn, respectively. Furthermore, the CeMg and CeZn showed a complete solid solubility. The complete solubility was confirmed by a diffusion couple made from alloys containing CeMg and CeZn compounds.

Influence of the administration of selenium compounds on tissue magnesium concentration in rats

Magnesium and selenium belong to important bioelements. Magnesium is the second most abundant intracellular macroelement, which takes part in the metabolism of carbohydrates, nucleic acids, protein and lipids. Selenium is an essential microelement, whose deficit has been stated in many different pathological states. Much research on safe and effective selenium supplementation has been performed for the last fifty years but the results still remain unsatisfactory. The aim of our study was to investigate the influence of inorganic sodium selenite Na 2 SeO 3 and two selenoorganic compounds synthetized at our chair on magnesium concentration in tissues of adolescent male Wistar rats. Inorganic selenite was administered as a water solution, whereas organic compounds: 4-(o-tolilo)-selenosemikarbazyd of 2-chlorobenzoic acid of a chain structure (ORG-C) and 3-(o-chlorobenzoylamino)-2-(o-tolylimino)-4-methyl-4-selenazoline of a ring structure (ORG-R) were suspended in emulsion (oil, arabic gum and water). Selenium compounds were given to rats at a dose of 5⋅10 –4 mg Se g –1 b.w. once a day for a period of 10 days. The control group was treated with saline. The administration was performed with use of a stomach tube. In comparison to the control group, selenium supplementation caused decrease in magnesium concentration in kidney and lung tissues, but did not cause any changes in the brain and heart muscle. In the liver and spleen it was only ring selenazoline that affected magnesium concentration, increasing it in the liver and decreasing in the spleen. In the femoral muscle it was only the selenosemicarbazide chain that exerted the significant effect causing a decrease in Mg concentration vs the control group. Selenium supplementation influences the tissue magnesium concentrations depending on tissue and structure of the supplement. Irrespective of the administered compound, it lowered magnesium in kidneys and lungs but caused no changes in the brain and heart muscle. In the liver, spleen and femoral muscle, alterations in the magnesium concentration were dependent on the provided supplement.

Relationship between δ18O and minor element composition of Terebratalia transversa

ABSTRACTWith their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.

Diagenetic stabilization pathways of magnesian calcites

Stabilization of high magnesian calcites (>4 mole% MgCO3) to low magnesian calcite (0–4 mole% MgCO3) and dolomite involves a reduction in the solubility of these phases during diagenetic alteration. The solubility of a magnesian calcite is controlled not only by the Mg concentration, but also other chemical and physical properties of the solid. These other properties include the amount of: 1) trace element diluents other than Mg (e.g., sodium, sulfate, adsorbed or structural water); 2) carbonate ion positional or cation ordering: 3) microstructural and surface defects; and 4) adhered small particles. Crystal size also may affect the solubility of a magnesian calcite. A magnesian calcite may become more stable in the natural environment by a decrease in Mg concentration, by loss of other trace elements and/or changes in its physical properties. Few studies exist of magnesian calcites in sediments and limestones undergoing diagenetic alteration that can be used to document the typical stabilization pathways followed by magnesian calcites. Several stabilization pathways are proposed, based mainly on experimental and theoretical arguments, to encourage further investigation of magnesian calcite diagenesis.

魚肉ねり製品の製造工程におけるポリリン酸塩の消長に及ぼす水晒しの影響

The washing effect of minced fish muscle on the degradation of polyphosphates (PP) in the salted meat paste (SMP) during the setting process was studied. Surimi MWO-MW4 were made from minced Walleye pollack muscle by washing 0-4 times with a buffer solution (pH 7.5). Aliquots of the SMP MWO-MW4, which were mixtures of surimi MWO-MW4, NaCl, and tripolyphosphate (P3), were incubated at 20°C. Degradations of P3 and pyrophosphate (P2) in the SMP during the setting process were determined. In the SMP MWO, P3 was rapidly degraded to P2 and P2 thus formed was also rapidly degraded to orthophosphate. As the number of washing times increased, the degradation rates of both P3 and P2 slowed down and P2 became hard to be degraded in SMP MW2-MW4. In order to determine the mechanism of this phenomenon, the amounts of tripolyphosphatase (P3ase), pyrophosphatase (P2ase) and magnesium (Mg) as an enzyme activator in surimi MWO-MW4 were measured. Along with the washings, P2ase and Mg were washed out from minced muscle, but P3ase was not. The decrease in Mg concentration suppressed P3ase activity in the SMP. Thus, repeated washing of minced muscle seemed to have an effect to degrade P3 and P2 in the SMP during the setting process.

The utilization of alkali-treated wheat straw: effects of neutralization of residual alkali and potassium supplementation on growth and mineral balance of male calves

ABSTRACTThe mineral balance of male calves given neutralized (with HC1) and unneutralized 35 g NaOH per kg treated wheat straw (WS), was determined in a digestibility trial in which WS was offered at inclusion levels of 300, 500 and 700 g/kg diet. The ratio of apparently retained sodium (Na) and potassium (K) increased with increasing proportion of straw in the diet and was lower on neutralized straw diets.The effect of supplementation with 3 and 6 g K per kg diet dry matter in a diet comprising approximately 500 g/kg of 35 g NaOH per kg treated WS, on performance, mineral status and acidbase balance was examined in a growth trial with 56 Israeli-Friesian male calves. The animals on the untreated WS diet had significantly (P< 0·05) less fat in the large depots and lower fat trim of carcass than did animals on the treated WS diets. No other differences in performance were significant. Ammonia concentration in rumen liquor and urea in blood were lower in the animals given alkali-treated WS. The concentrations of Na, K and chlorine in blood serum of the experimental animals were not affected by the treatment. The data on Na, K and magnesium (Mg) in muscle show depletion of Na and K and a trend towards a decrease in Mg concentration. K supplementation reduced the extent of depletion of Na and K. In bone, only Na was affected by the feeding of alkali-treated WS, the pattern being the same as in the muscle. The blood acid-base balance of the experimental animals was not significantly affected by treatments. The values of pH, actual bicarbonate and pCO2 of the animals given 35 g/kg alkali-treated WS indicate mild alkalosis in those animals. This alkalotic state did not affect performance. It appears that there is no Na loading problem which might interfere with growth.

Deposition of cadmium in organ tissues and excretion through hair following oral administration of cadmium acetate to rats

In an attempt to evaluate hair analysis as an indicator of cadmium (Cd) deposition into organs of a population exposed to Cd in the environment via food and drinking water, an animal experiment was performed using rats.Cadmium acetate (5mg/kg/day) was orally administered using stomach tubes to two groups of male rats, each of which comprised ten in number, for three and six consecutive weeks, respectively. In place of cadmium acetate, destilled water was administered to two groups of control rats in the same manner for the same periods. At the termination of administration, all the rats were sacrificed and liver, kidney, femur, heart, spleen, lung, and blood tissues, as well as newgrown hair were dissected out. All the samples were analysed for Cd, lead (Pb), iron (Fe) and magnesium (Mg). As a result, the following findings were obtained.1) The level of Cd concentration in all the organs, including blood and hair, was significantly higher in both of the exposed groups than in the control groups, indicating that hair analysis for Cd may provide a useful monitor for the estimation of Cd deposition into organs of populations exposed to Cd via food and drinking water.2) A remarkable deterioration in Pb concentration in bone was observed after the administration of Cd to rats. Cd exposure may induce a lowering of the Pb retention threshold of bone which results in an increase of Pb in blood.3) A decrease in Fe concentration was observed in the liver, kidney, bone and spleen of rats following exposure to Cd.4) A decrease in Mg concentration was observed in the bone, lung and blood of rats after the administration of Cd.

Variation in the Concentration of Certain Elements in Muscadine Grape Leaves Related to Season, Leaf Portion, and Age1

Abstract Chemical analysis of 3 portions (margin, midrib, and petiole) of immature and mature muscadine grape leaves (Vitis rotundifolia Michx. cv. Scuppernong) were carried out from samples collected at six 3-week intervals in 1971. The concentrations of N, Mn, Fe were higher in the leaf blade than in the petioles. Concentration of P, K, Ca, Mg, Cu, and Zn were higher in petioles than in the leaf blades. Difference in elemental concentration in the 2 portions of the leaf blade were evident only with K and Mn. The concentrations of Mg in the 2 portions of the blade were the same early in the season and decreased during the season, but the rate of decrease in the margin portion tended to be more rapid than in the midrib after the second sampling date. The decrease in Mg concentration in the blade coincides with the appearance of visual Mg deficiency symptoms. Seasonal variation was evident for all elements analyzed but slopes of the curves of the different leaf portions for a given element were often quite different. Data are presented for elemental concentration of 3 leaf portions of immature and mature leaves. In all cases, except B, elemental concentrations varied with leaf portions.

Ca-Releasing Action of β,γ-Methylene Adenosine Triphosphate on Fragmented Sarcoplasmic Reticulum1

beta,gamma-Methylene adenosine triphosphate (AMPOPCP) has two effects on fragmented sarcoplasmic reticulum (FSR), i.e., inhibition of the rate of Ca uptake and the induction of Ca release from FSR filled with Ca. The Ca release brought about by AMPOPCP has many features in common with the mechanism of Ca-induced Ca release: i) it is inhibited by 10 mM procaine; ii) the amount of Ca release increases with increase in the extent of saturation of FSR with Ca; iii) increase of the Ca concentration in the extent of saturation of FSR with Ca; iii) increase of the Ca concentration in the medium facilitates the release of Ca. However, no facilitation of Ca release upon decrease of Mg concentration in the medium is observable. AMPOPCP and caffeine potentiate each other remarkably in their Ca-releasing action, irrespective of the kind of substrate. From the mode of action of AMPOPCP on the rate of Ca uptake, the amount of phosphorylated intermediate (EP), and the effect on Sr release, it is suggested that the state of the FSR-ATP complex is crucial for Ca-induced Ca release.

Effect of diuretics on the secretion and reabsorption of ions in the kidney of marine teleosts

1. 1. Black sculpine with partly aglomerular kidneys from the Barents Sea and black sculpine with glomerular kidneys from the White Sea as well as scorpion fish and mullet from the Black Sea were injected intramuscularly with Lasix, Edecrin, Brinaldix and Diamox. The kidneys of the different species of these fish showed wide variations in their reactions to the injection of diuretics. 2. 2. Following injection of Lasix, Edecrin and Brinaldix, a significant increase in the Na concentration of the urine from black sculpine and mullet was observed, associated with a decrease in Mg concentration in the former and with a sharp increase in chloride concentration in the latter. 3. 3. In experiments performed on black sculpine after simultaneous injection with diuretics and sodium sulphate it was found that diuretics while inhibiting Na reabsorption do not affect sulphate secretion. 4. 4. Lasix, Edecrin and Brinaldix seem to affect primarily Na reabsorption, while the change in the urinary concentration and excretion of other ions depends on the interrelationship between the tubular transport of Na and these ions.

Effect of magnesium deficiency in the hen on egg production and hatchability of eggs.

Synopsis The influence of the level of magnesium (Mg) in the ration on reproduction by the hen was studied in 2 experiments. In experiment 1, it was found that feeding a semi‐purified ration, containing 56 p.p.m. of Mg, resulted in decreased egg production and reduced serum Mg concentration within 10 to 14 days. Although fertility of eggs was not affected noticeably by Mg deficiency, hatchability of fertile eggs was decreased markedly. The influence of inadequate dietary Mg was partially alleviated by adding 250 p.p.m. Mg to the ration. In experiment 2, a decline in hatchability preceded decreases in egg production and food consumption. A decrease in Mg concentration in egg contents accompanied the decline in hatchability. Hens fed rations containing 50 or 150 p.p.m. added Mg produced eggs of relatively low hatchability by day 14 of the trial. Subsequent to being fed a ration containing 550 p.p.m. added Mg, these hens increased in rate of egg production while hatchability of fertile eggs also increased. The results indicate that the dietary Mg requirement of the laying hen, sufficient to maintain a high rate of production of eggs which hatch satisfactorily, is 400 or more p.p.m.