UBC Theses and Dissertations
Sulphate salts affect water consumption : drinking behaviour and welfare of beef cattle Zimmerman, Amanda Shilo
Sulphate (SO₄) salts are present in many rangeland water sources and can negatively affect animal welfare and production. Existing guidelines for SO₄ in cattle drinking water are based on Na₂SO₄ although many water sources contain higher MgSO₄ concentrations. This research examined the role that MgSO₄ plays in water consumption, drinking behaviour and health of beef cattle. In a series of three experiments, yearling beef cattle were given water containing a range of SO₄ levels (1 - 4806 ppm) as Na₂SO₄, MgSO₄ or K₂SO₄. In Experiment 1, water consumption by eight heifers given either tapwater or water containing Na₂SO₄, MgSO₄ or K₂SO₄ at a target concentration of 3000 ppm SO₄ was monitored in a 4x4 Latin Square with 7-d treatment periods. Experiment 2 used eight yearling heifers, watered with tapwater or water containing Na₂SO₄ or MgSO₄ at target concentrations of 1500, 3000 or 4500 ppm SO₄, in 2-d treatment periods separated by 2 d tapwater access. In Experiment 3, 16 yearling heifers and steers were given tapwater or water containing Na₂SO₄ at a target concentration of 2000 ppm SO₄ , or MgSO₄ at target concentrations of 2000 and 4000 ppm SO₄ in 21-d treatment periods separated by 7 d tapwater access. Both Na₂SO₄ and MgSO₄ showed a dose effect with a stronger negative response for MgSO₄ than Na₂SO₄ (P ≤ 0.01). Average daily water consumption did not vary (P ≥ 0.05) between tapwater and SO₄ salts at either 2000 or 3000 ppm SO₄, but declined significantly at and above 4000 ppm SO₄ (P ≤ 0.01). Variability in consumption between drinking events increased as MgSO₄ content rose, as did the number of refusals to drink (P ≤ 0.05). Percent fecal DM, tested after 7, 11 and 21 d on treatment, increased following 21 d of MgSO₄ consumption at approximately 4000 ppm SO₄ (P ≤ 0.05), but no effect was seen at lower SO₄ concentrations (for any salt) or over shorter durations (7 and 11 d). These findings indicate that cattle find MgSO₄ aversive and at sufficiently high concentrations or length of exposure, water consumption, drinking behaviour and physiological status are disrupted.
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