| In order to study the mechanism of avian gout caused by high dietary calcium and provide a theory basis for preventing of gout, studies on avian gout induced by high dietary calcium in vivo and in vitro were conducted. The present study included three series as follows:In experimental 1, 1 00 pullets of 35 days old were selected for the experiment. The pullets were divided randomly into the control group and the experimental group. The pullets in the control group were fed with a normal diet and the pullets in the experimental group were fed with a high calcium diet (3.85%). The pullets in both the experimental group and the control group were colostomized, and the urine was collected to quantify high dietary calcium effects on urine and urinary deposit composition. The results showed that excessive dietary calcium during the pullets growing phase could cause several damage of kidney. The pullets raised on the high calcium diet had higher urine pH, but not significantly when compared with the control, and significantly larger volume of urine when compared with the control. The high dietary calcium significantly decreased the relative contents of potassium, calcium (p<0.01), sodium and magnesium (p<0.05) in urine compared with the control. The high dietary calcium increased the total content of calcium (p<0.01), uric acid, magnesium, inorganic phosphorous (p<0.05) in urine, but decreased the total contents of sodium (p<0.01), potassium (p<0.05) in urine. Scanning electron micrograph of urinary deposit showed that high dietary calcium could change the crystal structure. The results of X-ray energy dispersive spectrometer revealed that calcium, phosphorus increased and sodium, potassium decreased in the urinary deposit in the experimental group compared with the control group.In experimental 2, one hundred and twenty 35 days of age, healthy pullets were divided randomly into three groups. A basic diet was fed to the control pullets. The pullets in the other two experimental groups were fed with a high calcium (3.80%), normal protein (17.83%) diet (HC), and a high calcium (3.55%), high protein (24.58%) diet (HCHP) respectively. All the pullets were fed for 30 days. The results were as follows: the HC diet could cause severel damage of kidney, typical visceral gout was not found in pullets raisedon it. The HC diet significantly increased plasma uric acid and sodium (p<0.05), but decreased plasma inorganic P (P<0.01) of pullets when compared with the control group. Pullets raised on HC diet had higher fractional of calcium (p<0.01), magnesium, Inorganic P and potassium (p<0.05) significantly, and had significantly lower fractional sodium (p<0.05) in urine when compared with pullets raised on normal diet. Most of the pullets in HCHP group developed visceral gout. The HCHP increased plasma uric acid (p<0.01) and calcium (p<0.05) significantly. The pullets raised on HCHP diet had significantly higher fractional of calcium, magnesium (p<0.01) and inorganic P, potassium (p<0.05), significantly lower fractional sodium (P<0.05) in urine when compared with pullets raised on normal diet. Scanning electron micrograph of urinary deposit showed that HC and HCHP could change the construction of crystals in urinary deposit. The results of X-ray energy dispersive spectrometer revealed that calcium, phosphorus increased and sodium, potassium decreased in the urinary deposit of both the group of HC and HCHP compared with the control group, the urinary deposit of pullets in the group of HCHP had the highest level of inorganic P of all, and the urinary deposit of pullets in the HC had the highest level of calcium in the three groups.In experimental 3, the method of new-born chicken's renal tubule cells primary culture in vitro was established and used as the model of studying the mechanism of avian renal tubules cells' injury caused by high extracellular calcium. The viability of the cells was examined by MTT colorimetric analysis, and the injury of cellular membrane was detected through the levels of LDH released in cult...
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