Potential of alfalfa as a source of calcium for calcium deficient horses

Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Roslin, Midlothian.

The potential of short-cutting cycle, high temperature-dried alfalfa as a source of calcium for horses was determined by means of a 4 x 4 Latin square digestibility trial using four thoroughbred horses (mean liveweight 531 kg). The four dietary treatments were timothy hay alone, 33 per cent alfalfa and 67 per cent timothy hay, 67 per cent alfalfa and 33 per cent timothy hay, and alfalfa alone. Significantly more calcium and magnesium were absorbed from the alfalfa than from the hay. Phosphorus absorption appeared to be unaffected by treatment. Alfalfa calcium was more available than timothy hay calcium (apparent absorption coefficients of 0.78 and 0.15, respectively) and there was less variation between individual horses in their ability to absorb calcium from alfalfa. Horses fed alfalfa had significantly higher creatinine clearance ratios for calcium (P less than 0.01) and magnesium (P less than 0.001) than horses fed hay, but the creatinine clearance ratio for phosphorus was lower in horses fed hay alone.