Effects of saline drinking water on growth and water and feed intakes of weaner heifers

Abstract

Nine groups of four Hereford heifers (mean ¦ s.e. liveweight 223 ¦ 3.1 kg), drank water containing either high (650 ppm) or low (10 ppm) magnesium concentrations combined with varying levels (5000,7000,9000, 11 000 ppm) of total soluble salts (TSS) for 79 days. At each level of TSS, high magnesium treatments were obtained by replacing 2550 pprn sodium chloride with an equal amount of magnesium chloride. A control group drank water containing 10 pprn Mg and 2 10 pprn TSS. All animals werq kept in feedlots and fed on hay ad libitum. Mean daily maximum temperature and mean daily evaporation during the experiment were 23¦C and 4.6 mm, respectively. At the various TSS levels, the presence or absence of high levels of magnesium did not significantly affect liveweight gain, feed intake or animal health which suggests that the adverse effects of sodium and magnesium are similar. However, during the first 51 days of the experiment, heifers drinking water containing 11 000 pprn TSS and 650 ppm Mg lost weight and ate less than all other groups. Compared with control animals, those drinking water containing more than 5000 pprn TSS showed reduced liveweight gain (P<0.05) and feed intake during the first 5 1 days of the experiment, but this effect diminished as the experiment progressed. Overall, a TSS level of 5000 ppm caused a large but non-significant reduction in liveweight gain (36.3 v. 25.9 kg) over the 79-day period while a level of 11 000 ppm reduced liveweight by 49% (36.3 v 18.5 kg, P < 0.05)