Gluconeogenesis from caecal propionate in the horse.

The production of propionate in the caecum of the horse has been measured in two Shetland-type ponies fitted with caecal and colonic cannulas and fed on hay or on hay and wheat bran. A continuous intracaecal infusion of 14C-labelled sodium propionate was used and samples were obtained from a cannula at the origin of the right ventral colon. A simultaneous intravenous infusion of [2-3H]glucose was used to measure total glucose entry. On a hay diet which provided 177 kJ/kg body-weight per d, mean caecal propionate production was 19.6 (range 17.2-21.2) mg/h per kg body-weight and on a hay and wheat bran diet, which provided 187 kJ/kg body-weight per d, mean caecal propionate production was 34.0 (range 28.9-38.3) mg/h per kg body-weight. Mean total glucose production (mg/h per kg body-weight) in one pony was 104 (range 100-110) and in the other 135 (range 123-153). Rates were not influenced by diet. About 7% of total glucose production was derived from propionate produced in the caecum and this percentage was unaffected by diet or by individual animals.