PLASMA SILICON AND RADIOGRAPHIC BONE-DENSITY IN WEANLING QUARTER HORSES FED SODIUM ZEOLITE A1

Sixty Quarter Horse weanlings were used in a study to determine the efficacy of sodium zeolite A for increasing plasma silicon and radiographic bone density. The weanlings were randomly divided into four groups. Beginning at six months of age, they were individually fed a diet of 25% Bermudagrass hay and 75% concentrate for 168 days. Dietary treatments were 0,.66, 1.32 or 2.00% sodium zeolite A (SZA) as fed. The horses were managed in dry lots with free access to water and exercise. Twice daily the weanlings were separated, fed individually and allowed to eat to appetite for three hours. The weanlings were weighed, and height was measured at the withers and hip, initially and every 28 days. Anterior-posterior radiographs of the third metacarpus were taken initially and at 56-day intervals. The radiographs were scanned and bone density is expressed as radiographic aluminum equivalents (RBAE). At 84 days, jugular blood samples were taken for silicon analyses. There were no significant differences in feed intake, weight gain, heartgirth circumference, or height gain at the withers and hips. Feeding SZA resulted in increased (P<.05) plasma silicon concentrations. The gain in RBAE during the first 56 days of the trial tended to be largest in the horses fed the highest dietary concentration of SZA. However, there were no significant differences in RBAE between dietary treatments over the 168-day trial.