• 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.

• 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.

• 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.

• Journal of Veterinary Clinics
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• v.32 no.1
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• pp.69-72
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• 2015

This study was performed to differentiate calcium oxalate and struvite canine urinary stones using computed tomography. A total of 38 urinary stones (8 calcium oxalate and 30 struvite) were scanned using a computed tomography scanner. These urinary stones (10-15 mm diameter) extracted surgically without fragmentation were obtained from the different individual patients. The stone's Hounsfield units(HU) values, heterogenicity, and roughness of surface were evaluated to differentiate calcium oxalate and struvite. The HU values of calcium oxalate were significantly higher than those of struvite. A receiver operator characteristic (ROC) curve revealed 1272 as the best threshold value to distinguish calcium oxalate from struvite (ROC curve AUC 0.87, p < 0.0014). The heterogenicity of calcium oxalate and struvite significantly differed on bone and dental window setting (p < 0.0001). There was no significant difference between calcium oxalate and struvite in roughness of surface. On computed tomographic images, bone and dental windows setting were useful for evaluation of heterogenicity between calcium oxalate and struvite. The HU value and heterogenicity are highly promising factor that can distinguish calcium oxalate and struvite with reasonable accuracy.

• 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.

• 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.

• 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.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.7
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• pp.940-945
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• 2011

In order to determine whether oxalate from grasses affects feed intake, blood calcium (Ca) and other blood parameters of adult sheep, two feeding trials were conducted. In Trial 1, one group of sheep received guineagrass (0.47% soluble oxalate) and another group received setaria (1.34% soluble oxalate) for 28 d. In Trial 2, one group of sheep received guineagrass while another group received the same grass treated with an oxalic acid solution (at a rate of 30 g oxalic acid/kg dry matter of hay) for 72 d. All sheep received concentrate mixtures (0.5% of body weight) throughout the experiment. In both trials, it was observed that plasma Ca concentration (11.0-11.7 mg/dl) was significantly (p<0.05) lower in sheep fed high oxalate-containing grasses than in sheep fed low oxalate-containing grasses (12.4-13.7 mg/dl). No differences (p>0.05) were observed in concentrations of magnesium, phosphorus and parathyroid hormone in plasma between the feeding of low and high oxalate-containing grasses. In addition, no differences (p>0.05) were observed in roughage dry mater (DM) intake, total DM intake or body weight of sheep. This study suggests that sheep may consume oxalate-rich forage, but Ca bioavailability may decrease with increasing oxalate levels in the ration.

• Analytical Science and Technology
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• v.8 no.4
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• pp.877-880
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• 1995

The determination of fluoride and the nutritious calcium in infusion of teas are explained. Tea leaves were pulverized and were immersed in boiling water. The solution was filtered and fluoride, calcium and oxalic acid were determined by the ion chromatography. The quantities of fluoride, calcium and oxalate ions extracted from 100 g of tea leaves were calculated. Tea leaves were also immersed in 0.5 M hydrochloric acid and extracted oxalate and calcium ions were analyzed. The free oxalic acid and calcium were extracted in boiling water and the total ones were extracted in hydrochloric acid. The quantity of calcium oxalate was calculated from the total and the free oxalic acids. The free calcium was estimated to be nutritious.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1706-1710
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• 2011

An experiment was conducted to investigate the effects of calcium (Ca) fertilization on oxalate content in napiergrass (Pennisetum purpureum) and on some blood parameters of sheep. Re-growth napiergrass was grown with or without Ca fertilizer and offered to sheep. Eight sheep, divided into two groups of 4 animals each were used. Calcium-fertilized napiergrass was offered daily to the animals as experimental treatment, whereas without Ca-fertilized napiergrass was given to the animals as control. Results showed that there was a trend to lower soluble and total oxalate concentrations in Ca-fertilized grass than control. The Ca-fertilized grass contained (p<0.05) lower concentrations of K and Mg than control, though Ca fertilization had no affect (p>0.05) on Ca and Na concentrations in plants. Feeding of Ca-fertilized grass had no affect on the feed consumption, blood Mg level and daily gain of sheep. However, sheep fed control grass had lower (p<0.05) blood Ca level than sheep fed Ca-fertilized grass. Our findings suggest that Ca fertilization might minimize the negative effects of oxalate.