Providing Dietary Calcium and Phosphorus to Horses ...
Nov 01, 2011· Approximately 60 g (two ounces) of limestone each day is required. Thoroughbred mares in late pregnancy and lactation should be given 90 g (three ounces) of limestone daily. Horses being fed on dry pasture with hay supplement may require phosphorus to improve the palatability and availability of the calcium in the feed.