Influence of Feed Particle Density on Paniculate Passage from Rumen of Holstein Cow

Abstract

The response of rumen turnover rate to increasing alfalfa fiber density or chromium concentration was evaluated. Alfalfa fiber density was elevated by mordanting with increasing chromium concentrations. As chromium concentration of the mordanting solution was raised, there was a concomitant increase of chromium content and density of the resultant alfalfa fiber. Two Holstein cows were fed for ad libitum consumption equal portions of a total mixed ration three times a day. Cows were fed a pulse dose of marker, and fecal grab samples were collected at scheduled intervals for 5 days. Chromium analysis was on the undigested cell wall. By linear regression analysis the slope was fit for the declining phase of the marker excretion curve. Rumen turnover rates (h−1) and cell wall densities (g/ml) were: .0107, 1.126; .0072, 1.165; .0191, 1.242; .0228, 1.396; and .0194, 1.703 for alfalfa cell wall mordanted with 2, 4, 8, 16, or 32% chromium concentrations. Particle density and chromium concentration may be important factors affecting rate of particle turnover in the rumen.