Rumen epithelium cell proliferation accelerated by propionate and acetate.

Ruminal papillae were biopsied from fasted adult sheep given 18 m mole/kg body weight per day of sodium propionate or sodium acetate intraruminally via fistula. The mitotic index of the epithelial cells in the papillae was estimated for the mitogenic effect of the acids. Before the administrations, mitotic indices were lower than .53%. They increased after a few days' propionate-administration, then declined. The peak values appeared on 2 or 4 days of the administration and were 1.64%, 1.38%, 1.73%, and 1.54% in four trials. Mitotic indices also increased from acetate and declined. The peak values appeared on 3 or 4 days of the administration and were 2.04%, 2.49%, 1.70%, and 2.03% in four trials. Mitotic indices of the control sheep given the same amount of .9% saline were lower than .28%. The mitogenic effect of propionate and acetate on the rumen epithelial cells was apparent, but it seems to be weaker than that of butyrate judged from the relatively slow rise of the index in this study.