Effects of portal volatile fatty acid infusions on meal patterns and blood composition in goats

Adult goats, provided with permanent jugular and portal vein catheters, were used to study whether circulating volatile fatty acids (VFA) or lactate might act as feedback signals in the control of meal size and/or frequency. Subjects were fed ad lib a pelleted diet supplemented with 100 g hay. Feed intake was recorded continuously. Portal infusions, mimicking the normal route of absorption, were made at a constant rate during 4 hours with isotonic or slightly hypertonic solutions of sodium salts of VFA or lactate, and their effects on feeding behavior and peripheral blood were determined. In spite of high blood concentrations reached, infusion of acetate, propionate, n-butyrate, isobutyrate or lactate did not change total 4-hr feed intake, meals size or intermeal interval. Neither did infusion of mixtures of VFA affect meal patterns. It is concluded that, if circulating VFA or lactate play a role at all in the control of feeding in the goat, the feedback signal does not arise from portal or peripheral blood