Functional Specific Gravity of Ground Hay Samples in Ionic Solutions

Abstract
Specific gravity of forages affects rate of passage from the rumen. Ionic concentration influences rate of change of specific gravity of forage particles, but it has not been established whether some ions influence rate of change of functional specific gravity more than others. Effects of solutions containing half and 2-fold the ionic concentration of standard buffer were compared with water and with standard. Samples in more concentrated solutions had higher specific gravities than those in more dilute, less basic liquids. Effects of different ions also were investigated. In solutions with ionic concentrations similar to mixed saliva, specific gravities of samples in solutions containing Na and K were higher than those in solutions with Ca and Mg. With equivalent Na concentrations, disodium phosphate solutions increased specific gravity of forages more than did solutions with NaCl. At equal phosphate concentrations, samples in solutions containing disodium phosphate had higher specific gravities than did those in monosodium phosphate or water. Samples in ammonium phosphate solution had lower specific gravity readings than did those in dipotassium or disodium phosphate. Ionic composition, pH and osmolality influenced forage specific gravity in vitro.