FACTORS INFLUENCING BACTERIAL ATTACHMENT TO THE RUMINAL EPITHELIUM IN-VITRO

Some factors influencing bacterial attachment to the rumen epithelium were studied in vitro using mixed rumen bacteria (upper-or lower-layer bacteria formed at bacterial sediment by centrifugation), isolated fr om steers fed a roughage diet, and rumen epithelial cells collected fr om beef cattle given low-concentrate (50%; LC) and high-concentrate (9 0%; HC) diets. Optimal incubation conditions for bacterial attachment to rumen epithelial cells were 39 degrees C for 30 min. The bacteria i solated from the upper layer had a higher attaching activity to the LC epithelial cells than those of the lower layer. A higher degree of ba cterial attachment was observed using the rumen epithelium from steers fed the LC diet rather than the HC diet (p<0.01). Ethylenediamine dih ydroiodide (EDDl) added at 10 through 40 mu g l/ml increased bacterial attachment to the HC epithelial cells. Ammonia at 50 through 100 mu g /ml positively affected bacterial attachment to both LC and HC epithel ial cells. Bacterial attachment to the HC epithelial cells was enhance d (p<0.01) by the addition of a reducing agent (L-cysteine HCl) but no increase was noted with LC cells. L-or D-lactate, volatile and unsatu rated fatty acids markedly decreased bacterial attachment to rumen epi thelial cells.