• Asian-Australasian Journal of Animal Sciences
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• v.23 no.6
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• pp.719-723
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• 2010

Ingestion of forage containing a large quantity of soluble oxalate can result in calcium deficiency and even death of livestock. Fertilization is one of the most practical and effective ways to improve yield and nutritional quality of forage. An experiment was conducted to determine the effects of nitrogen (N) fertilization (150, 300 and 600 kg/ha) across varying levels (150, 300 and 600 kg/ha) of potassium (K) on oxalate accumulation in napiergrass (Pennisetum purpureum). Application of N at 300 kg/ha produced higher dry matter yield than at 150 or 600 kg/ha, while K fertilization had no effect on yield. In general, N fertilization did not affect the soluble and total oxalate contents, but slightly affected the insoluble oxalate content. Soluble oxalate content showed an increasing trend and insoluble oxalate content showed a decreasing trend with increasing K level, but total oxalate content remained relatively constant. There were significant interactions between N and K fertilization for the content of soluble and insoluble oxalate fractions. The greatest increase in soluble oxalate content with N level at 300 kg/ha was found at the high level (600 kg/ha) of K application. The greatest increase in insoluble oxalate content with N level at 600 kg/ha was found at the low level (150 kg/ha) of K application. These results indicated the possibility of controlling the content of soluble and insoluble oxalate fractions in forage by fertilization.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.3
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• pp.439-448
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• 2011

Oxalic acid is synthesized by a wide range of plants. A few of them are forage plants that can cause oxalate poisoning in ruminants under certain conditions. In this paper, the role of some agronomic, climatic and genetic factors in minimizing oxalate accumulation in forage plants has been discussed. Research indicates that the content of oxalate in forage can be controlled by fertilizer application. For example, nitrate application resulted in higher contents of soluble and insoluble oxalates than ammonium application. With an increased rate of potassium application, soluble oxalate content showed an increasing trend and insoluble oxalate content showed a decreasing trend. With an increased rate of calcium application, soluble oxalate content showed a decreasing trend and insoluble oxalate content showed a reverse trend. Other agronomic factors such as growing season, harvesting practices, plant maturity, plant species, plant variety and plant parts can also have a large effect on oxalate accumulation. However, the potential benefits of the above approaches for improving forage quality have not been fully exploited. In addition, there is still insufficient information to fully utilize means (e.g. plant nutrients, season and soil moisture) to minimize oxalate accumulation in forage plants. Therefore, more research is required for a better understanding of the interactions between oxalate and the above-mentioned factors in forage plants.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1599-1603
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• 2008

Sodium is involved in elevation of oxalate content in some plant species and this element is abundant in saline soils. Oxalate causes precipitation of insoluble calcium oxalate in the rumen and kidneys. The intention of this study was to evaluate the effect of soil salinity stress on dry matter yield and oxalate content in pot-grown napiergrass (Pennisetum purpureum Schumach). Plants were cut three times at 56, 118 and 179 d after transplanting to the pots. Five salinity treatments were used containing various concentrations of NaCl solution as follows: 0, 100, 300, 600 and 900 mM. At 28, 42, 84, 98, 146 and 160 d after transplanting, plants were irrigated with one liter of the particular treatment for each application. Dry matter yield of napiergrass was not affected (p>0.05) by salinity treatments. Plants treated with 100 mM NaCl exhibited a higher soluble oxalate content compared to other treatments, but the differences were not statistically significant (p>0.05). Although salinity treatments had significant (p<0.05) effects on insoluble and total oxalate contents in plant tissue between the 100 and 900 mM NaCl treatments, the differences were too small to be considered biologically important. The present study indicates that where the soil is high in NaCl, napiergrass will tend to grow well and be low in oxalate.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.2
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• pp.214-219
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• 2008

An experiment was conducted to evaluate the effects of nitrogen (N) level on the dry matter (DM) yield, N concentration and oxalate content of some tropical grasses, namely Rhodesgrass (Chloris gayana), Guineagrass (Panicum maximum) and Sudangrass (Sorghum vulgare). Three levels of N as urea were applied (Standard- 260, $Standard{\times}2$- 540 and$Standard{\times}4$- 1,060 kg N/ha for Rhodesgrass; Standard- 380, $Standard{\times}2$- 770 and $Standard{\times}4$- 1,570 kg N/ha for Guineagrass and Sudangrass) in a completely randomized design and grasses were harvested twice at approximately two-month intervals. Dry matter yield tended to be higher with increased rate of N fertilizer in all species, while further additional N ($Standard{\times}2$ or $Standard{\times}4$) did not significantly (p>0.05) further increase DM yield, when compared with the Standard level of N fertilizer application. There was also a trend towards higher N concentration in plants as N fertilization increased in all species and it was increased significantly in Rhodesgrass and Sudangrass (p<0.05 or p<0.01, respectively). Further additional N ($Standard{\times}2$ or $Standard{\times}4$) application showed no significant (p>0.05) differences on oxalate content in plant tissue within species, when compared with the Standard level of N. The Rhodesgrass contained 0.11, 0.13 and 0.15% soluble oxalate and 0.23, 0.25 and 0.27% total oxalate with Standard, $Standard{\times}2$ and $Standard{\times}4$ level of N application, respectively. The Guineagrass contained 0.54, 0.50 and 0.42% soluble oxalate and 1.60, 1.56 and 1.45% total oxalate with Standard, $Standard{\times}2$ and $Standard{\times}4$ level of N application, respectively. The Sudangrass contained 0.06, 0.15 and 0.12% soluble oxalate and 0.22, 0.22 and 0.21% total oxalate with Standard, $Standard{\times}2$ and $Standard{\times}4$ level of N application, respectively The results from this study suggest that these grasses do not use further addition of N fertilizer ($Standard{\times}2$ or $Standard{\times}4$) to form high content of oxalate salts, when compared with the Standard level of N. In addition, the levels of oxalate present with these grasses are quite low as far as toxicity to animals is concerned.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.1122-1127
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• 2008

A high dietary oxalate intake may lead to calcium oxalate (CaOx) kidney stones in the gastrointestinal tract. Most soy foods contain high concentrations of oxalate and/or phytate. This study analyzed the changes in oxalate (Ox), phytate ($InsP_6$), and calcium (Ca) during soymilk processing from the seeds of Korean recommended soybean cultivars (cvs). The contents of Ox, $InsP_6$, and Ca in 21 cvs ranged from 14, 108, and 148 to 231, 279, and 246 mg/100 g of dry seed, respectively. Seven cultivars were selected from the 21 cvs by the distributions of Ox, $InsP_6$, and Ca. Then, each contents of soymilk prepared from the 7 cvs were determined. All contents were lower in soymilk than in seeds, but the Ox to $InsP_6$ ratios changed from varying ratios (0.1-0.8) to normal ratios (0.8-1.0) in all cvs except 'Paldalkong'. Consequently, during soymilk processing, the Ox content was decreased and the $InsP_6$ content was remained higher than the Ox content although the Ox was likely to be less reductive than the $InsP_6$. These results may provide better information for minimizing the risk of formation of Ox kidney stones due to consumption of soy products.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.7
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• pp.870-878
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• 2009

This study was conducted to select the soybean cultivar to minimize the formation of calcium oxalate, and investigate the ingredients for total oxalate (Ox), phytate ($InsP_6$) and minerals such as calcium (Ca), magnesium (Mg), sodium (Na), zinc (Zn), and potassium (K) in 113 recommended soybean cultivars in Korea. Ca content ranged from 0.586 mg/g in Saealkong to 3.177 mg/g in Daolkong, and Mg content ranged from 0.559 mg/g in Taekwankong to 3.085 mg/g of dry seed in Seonheukkong. The total oxalate content ranged from 1.24 mg/g in Seonheukkong to 3.81 mg/g in Ilmikong, and InsP6 content ranged from 0.43 mg/g in Mailikong to 4.72 mg/g of dry seed in Dagikong. In the cross-correlation analysis for the contents of Ca, Mg, Ox and $InsP_6$, Seonheukkong and Danmi2 were selected to minimize the formation of calcium oxalate because the contents of Ca and $InsP_6$ were much higher than the content of Ox. These cultivars could be useful for producing soy foods beneficial to populations at risk for calcium oxalate kidney stones and for improved mineral bioavailability.

• Korean Journal of Environmental Agriculture
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• v.4 no.1
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• pp.31-36
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• 1985

In order to choose a suitable soil extractant for the prediction model of heavy metal content in brown rice, four extractants-0.1 M HCl, 0.1 M $HNO_3$, 0.1 M $NH_4$-oxalate and 0.001 M 2Na-EDTA, were compared by analyzing 84 soil and 45 brown rice samples collected from paddy fields adj-acent to five old zinc-mining sites. Content of cadmium and zinc in brown rice had the highest correlation coefficient to 0.001 M 2Na-EDTA and 0.1 M HCl extractants, respectively. However, the lead content in brown rice was significantly correlated with only 0.1 M $NH_4$oxalate solution. For the simultaneous prediction of zinc, cadmium and lead in brown rice, 0.1 M $NH_4$-oxalate solution was the most effective. On the multiple analysis by using various chemical characteristics of soils, pH and calcium content of soils were effective variables for the estimation of cadmium content in brown rice, while CEC and magnesium content were more effective for the estimation of zinc content in brown rice. Furthermore, for the estimation of lead content in brown rice, factors such as pH, CEC, calcium, magnesium, potassium and organic matter content were important variables in the multiple regression equation.

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.177-182
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• 2010

To synthesize $Gd_2O_3:Eu^{3+}$ phosphor, gadolinium-europium oxalate precursors were prepared from oxalic acid, NaOH or aqueous ammonia via coprecipitation method. The obtained precursors were heat-treated and then characterized by XRD, SEM and PL. The kinds and amounts of coprecipitant (NaOH or aqueous ammonia) were found to affect the powder morphology and properties of gadolinium-europium oxalate precursors. Two crystalline precursors and one amorphous precursor were synthesized. The nanometer-sized amorphous gadolinium-europium oxalate precursor was first prepared using the oxalate coprecipitation technique. The calcined powders obtained from the amorphous precursor were nearly spherical in shape, and a narrow size distribution was obtained. The NaOH coprecipitant was more effective in the preparation of nanometer-sized spherical powders. A thermal decomposition process was conducted for the three kinds of precursors. The photoluminescence property was also measured as a function of europium content, and concentration quenching occurred for samples with europium concentrations of over 10 mol%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1149-1155
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• 2010

This study was conducted to investigate the changes of quality characteristics, and mineral, oxalate and phytate content during soymilk process. The yields of soymilk ranged from 8.43 mL/g in Bokwangkong to 9.15 mL/g in Bongeuikong and Hannamkong, and total soluble solid contents were ranged from $4.37^{\circ}Brix$ in Anpyeongkong to $7.17^{\circ}Brix$ in Bongeuikong, respectively. The pH and total acidity of soymilk ranged from 6.43 to 6.86 and from 1.48% to 1.65%, respectively. The viscosity of soymilk was the highest value of 20.80 cP in Hannamkong and the lowest value of 15.73 cP in Dawonkong. The highest value of calcium content of soymilk was 1.589 mg/g in Seonheukkong, and oxalate and phytate in soymilk were high at 2.14 mg/g in Hannamkong and 2.18 mg/g in Anpyeongkong, respectively. The transfer ratio of oxalate from soybean to soymilk was the highest value of 77.6% in Jinpumkong 2, and one of the phytate was the highest value of 87.5% in Dongpuktae and the lowest value of 13.9% in Hojangkong.

• Food Science and Biotechnology
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• v.16 no.4
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• pp.650-654
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• 2007

Many vegetables contain oxalate at various levels depending on their type and family. Oxalate is known to reduce mineral bioavailability from foods. The following study was conducted to determine soluble and total oxalate contents in 32 plant samples commonly consumed in Korea using high-performance liquid chromatography (HPLC). Chard, amaranth, and spinach contained total oxalate of >1,000 mg/100 g. Approximately 45% of the oxalate in amaranth is insoluble, whereas 74.46 and 92.45% of the oxalates in chard and spinach, respectively, was soluble oxalates, which may be removed by blanching. Eggplant, carrot, leak, ginger root, spinach, burdock, and sweet pepper contained more than 90% soluble oxalate in total oxalate content. However, all oxalates detected in lettuce and celery were insoluble. Oxalate was not detected in shepherd's purse, bellflower root, garlic, radish root, broccoli, cabbage, onion, lotus root, adlay, cucumber, kale, and pumpkin. These observations provide useful information needed for selection of vegetables.