RELATION OF WATER TURNOVER TO FORMATION OF SILICEOUS CALCULI IN CALVES GIVEN HIGH-SALT SUPPLEMENTS ON RANGE

Abstract

In the spring of 1973 and 1974, two groups of 10 calves with their dams were allotted to adjacent 32-ha fields of native range in southern Alberta. A barley-based supplement containing 20% sodium chloride (salt) was offered the calves in one of the groups in 1973 and supplement containing 12% salt was offered the calves in one of the groups in 1974. The control calves received no supplement, but block salt was available. The experiment terminated at weaning in 1973 and 90 days after weaning in 1974. Supplement intake before weaning provided a total of 2.3 kg of salt/head in 1973 and 3.6 kg of salt/head in 1974, most of which was consumed during the last 30 days. After weaning in 1974, supplement intake provided a total of 22.9 kg of salt/head or an average of 254 g/day. In both years, mean water turnover of all calves in both groups increased from 5 kg/day at 35 days of age to 16 kg/day at 150 days of age. It remained at this level in supplemented calves and, in 1974, rose again after weaning to 29 kg/day. In control calves, it declined to 12 kg/day at 225 days of age and remained at that level. Water turnover per unit body weight raised to the 0.82 power (BW0.82) increased in all calves from 200 g/day at 35 days of age to 300 g/day at 90 days of age and then declined to 200 g/day at 180 days of age. In control calves, it continued to fall until it reached a steady 150 g/day. In supplemented calves, it did not fall below 200 g/day and, in 1974, rose again after weaning to give values of 300 g/day. In both years, control calves had a greater mean weight of calculi than supplemented calves. The difference was greater in 1974 because salt intake was greater before weaning than in 1973. While calculus formation was invariably low in calves with high water turnovers, it was not always high in calves with low water turnovers. This indicates that low water intake, leading to a high concentration of silicic acid in urine, is a necessary but not a sufficient condition for calculus formation. It is concluded that provision of high-salt supplements can be used as a means of eliminating the formation of siliceous calculi in range calves.