EFFECTS OF SHORT-CHAIN FATTY-ACIDS ON THE RUMEN MUCOSA AND ON THE PLASMA-LEVEL OF INSULIN AND GLUCAGON

The long-term effects of intraruminal loads of different short chain f atty acids (SCFA) on the rumen mucosa in correlation to plasma level o f insulin and glucagon were investigated. Four mature non-lactating, n onpregnant sheep fitted with rumen fistulae were all subjected to the following three treatments: (1) Hay feeding ad lib. (2) Hay feeding ad lib. in combination with intraruminal loads of a mixture of propionat e and butyrate twice daily. (3) Hay feeding in combination with intrar uminal loads of acetate twice daily. The experiment was performed duri ng three periods, each lasting for six weeks. The intraruminal loads o f the mixture of propionate/butyrate or acetate gave rise to elevated rumen fluid concentrations of the added acids, but no effect on rumen morphology, epithelial mitotic index or activity of the enzyme carboni c anhydrase was detected. The repeated loads with the propionate/butyr ate mixture, as well as the acetate solution decreased the basal level s of insulin and glucagon. It was suggested that SCFA might have a hit herto unknown inhibitory effect on the basal insulin and glucagon leve l in sheep. The result of the study indicates that it is difficult to manipulate the rumen fluid SCFA composition, in order to induce full d evelopment of the ruminal mucosa without providing excessive energy to dry ruminants.