Potassium, Phosphorus and Calcium Interrelationships Influencing Feedlot Performance and Phosphatic Urolithiasis in Lambs

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Abstract
Two levels of potassium (0.41 and 1.01%), two levels of phosphorus (0.24 and 0.57%) and two levels of calcium (0.28 and 1.20%) were used in a 2 × 2 × 2 factorially designed experiment to determine the influence of excess dietary potassium on feedlot performance and the formation of phosphatic urinary calculi in lambs fed various levels of phosphorus and calcium. A total of 240 Texas ewe lambs were allotted to the eight treatments. There was a tendency toward lower weight gains and feed consumption for lambs fed the higher level of dietary phosphorus. This effect was most pronounced in the presence of the highest level of potassium (1% potassium chloride added to the diet). Added calcium completely overcame these effects. No obstructive urinary calculi were observed in these ewe lambs. However, those fed the highest level of phosphorus and the lowest level of calcium had a 55 to 57% calculi incidence as determined at slaughter. While the incidence of urinary calculi was no different in the lambs fed the higher level of potassium, the average size of the urinary mineral deposits was larger amounting to 120 and 83 mg for lambs on treatments with and without 1% potassium chloride, respectively. Increasing the level of calcium to 1.20% of the diet reduced the calculi incidence to 17%. These data support the existence of a detrimental potassium-phosphorus interrelationship expressed in lambs fed elevated levels of each. Copyright © 1970. American Society of Animal Science . Copyright 1970 by American Society of Animal Science