100 EF D SO f O 5 Ha 29 aa — fx lor be we SE © <I a > a er ©) emesis | | i | DAY POST ADMINISTRATION FIGURE 1, E AVERAGE PERCENT OF VARIOUS SIZE SAND PARTICLES RETAINED BY COWS AFTER ORAL ADMINISTRATION. AVERAGE PARTICLE HALF500 F ‘TIME IN GI TRACT 3 ui 200 ., 100 ~ 50k cc LW ° AVERAGE PARTICLE RETENTION IN GI TRACT <I a DAYS FIGURE 2. HALF-T!IMES AND RETENTION TIMES FOR VARIOUS SIZE SILICA-SSAND PARTICLES IN THE DAIRY COW GI TRACT. 158