Experimentally Produced Urinary Calculi in Sheep

Abstract
The effects of some dietary factors on the incidence of urinary calculi in sheep and on urinary excretion are reported. Eighty crossbred white-faced wether lambs were divided into 16 lots of five sheep each and were fed a mixed grass-alfalfa hay for 100 days. Water and salt were available free-choice. During this period, no symptoms of urinary calculi were shown. Each lot was then placed on one of 16 pelleted concentrate-roughage diets for a period of 124 days. The experiment was of factorial design and the variables were phosphorus, potassium, beet pulp, and beet molasses in the diets. The occurrence of calculi was influenced greatly by treatment. Thirty-two days after the lambs were fed the experimental diets, the first case of calculi was recorded. A total of 36 cases of calculi was produced during the 124-day test period. The addition of potassium to the diets of 20 sheep resulted in seven cases of calculi, while a phosphorus addition caused only one case in 20 sheep. This difference was significant (P<.05). The addition of both phosphorus and potassium either as potassium acid phosphate or as phosphoric acid and potassium carbonate, resulted in 28 cases in 40 sheep, also a significant (P<.01) result. The inclusion of beet pulp in the diets of 40 sheep, at approximately 25% of the diet, resulted in 26 cases of calculi. Ten cases were found in 40 lambs receiving no beet pulp. The presence of beet molasses at approximately 11% of the diet had no effect on the occurrence of urinary calculi. The highest incidence of urinary calculi resulted when phosphorus, potassium, and beet pulp were all included in the diet. Out of 20 sheep receiving this type of diet, 19 developed calculi.

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