Published online by Cambridge University Press: 27 March 2009
A series of experiments investigated mineral supplements for the correction of negative calcium and phosphorus balances in horses fed tropical grass hays containing more than 0·5% total oxalate.
A daily supplement of a soluble calcium source was retained with an efficiency of 60% implying no interference with calcium absorption from supplements by oxalate or other factors in the hays.
The palatability of limestone, rock phosphate, dicalcium phosphate, a limestone and dicalcium phosphate mixture and mono-ammonium phosphate was tested with a view to providing a supplement once weekly. With the exception of the latter, all were consumed readily when mixed with 50–60 % molasses (w/w) and hourly intakes of 200 g calcium and 50 g phosphorus were recorded.
In balance trials using horses fed tropical grass hays, 1 kg of either rock phosphate, or a mixture of limestone and dicalcium phosphate (1:2, w/w), each mixed with 1·5 kg molasses, was fed on the 8th day of a 14-day balance trial. The retention of calcium from the supplements ranged from 19 to 41% and that of phosphorus from 22 to 42%. The passage time for unabsorbed minerals was about 4 days. This amount of supplementation can accommodate calcium and phosphorus losses of at least 20 and 10 mg/kg live weight/day respectively. A supplement of 1 kg limestone overcame a negative calcium balance of 20 mg/kg live weight/day but did not overcome a negative phosphorus balance.
Full text views reflects PDF downloads, PDFs sent to Google Drive, Dropbox and Kindle and HTML full text views.