Relationship of Dietary Mineral Intake to Urinary Mineral Excretion and the Incidence of Urinary Calculi in Lambs

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Abstract
A series of three experiments involving a total of 343 wether lambs was conducted to determine the relationship of dietary mineral intake to urinary mineral excretion and the incidence of urolithiasis. The effects of variation in dietary mineral intake on the levels of minerals in the urine were studied to determine whether certain physiological relationships existed which were conducive to the formation of urinary calculi. An increase in dietary phosphorus intake tended to be predisposing to the formation of urinary calculi of the magnesium-phosphate type. The calculogenic effect of the diet was reduced as the dietary intake of calcium and potassium increased. Lambs receiving the high phosphorus-low calcium diets had increased concentration of phosphate in the urine which was associated with a significant decrease in the urinary excretion of magnesium and of potassium. Lambs fed the high potassium diets excreted larger amounts of magnesium in the urine. A multiple correlation coefficient of 0.87 was found to relate the occurrence of urolithiasis to length of feeding period and dietary intake of calcium and potassium. The addition of sodium metasilicate to the diet did not increase the incidence of calculi. An increased intake of magnesium did not significantly change the occurrence of urolithiasis. Animals which received supplemental calcium and phosphorus in the form of bone meal readily developed calculi. Urinary pH, specific gravity, titratable acidity, total nitrogen, and ammonia nitrogen had no apparent relationship to the development of urolithiasis. Copyright © 1965. American Society of Animal Science . Copyright 1965 by American Society of Animal Science