Ovine Phosphatic Urolithiasis as Related to the Phosphorus and Calcium Contents and Acid-Base-Forming effects of All-Concentrate Diets

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Abstract
A 2×2×2 factorially designed experiment utilizing 240 wether lambs was conducted to determine the relative importance of a suboptimum level of calcium, an elevated level of dietary phosphorus and an alkaliforming effect of the diet in promoting phosphatic urinary calculi. Treatment variables incorporated into an all-concentrate, corn-soybean meal diet included 0.28 and 0.55% phosphorus, 0.14 and 0.28% calcium and 0 and 2% sodium bicarbonate. With a level of phosphorus (0.28%) that is only slightly in excess of requirements, a low calcium to phosphorus ratio (0.5−1:1) did not promote urinary calculi. Variations in phosphorus or sodium bicarbonate did not significantly affect feed consumption or weight gains, but the higher level of each gave a high incidence of urinary calculi. With the feeding of low (0.28%) and high (0.55%) levels of phosphorus without sodium bicarbonate, 8 and 85%, respectively, of the lambs developed urinary calculi. With the inclusion of sodium bicarbonate in the diet, 58 and 88% of lambs in corresponding groups were afflicted. The calculogenic variables, including sodium bicarbonate and an increase in dietary phosphorus, had the principal effects of increasing urine alkalinity by the former and serum and urinary phosphorus concentrations by the latter. Lambs on the calculogenic treatments showed no increase in nondialyzable urinary constituents including protein, hexose and hexosamine. Copyright © 1969. American Society of Animal Science . Copyright 1969 by American Society of Animal Science