Some physical properties including particle size, functional specific gravity (FSG; Teimouri Yansari et al., 2004), hydration rate, water holding capacity (WHC) and ionion-cation exchange (Van Soest, 1994) influenced on physically effective factor (pef), but only particle size measurement is central to all effective fibre systems. The objective of this study was to evaluate the effects of three types of beet pulp (BP) on physical characteristics including bulk density, particle size, kinetics of hydration, FSG, WHC, and intrinsic osmotic pressure that measured using in vitro and in situ methods.