Absorption of volatile fatty acids, tritiated water and antipyrine from the abomasum of goats.

Abstract

In conscious goats the abomasum was isolated temporarily from the rest of the gastro‐intestinal tract by means of balloons, or a double by‐pass or a snare around the pylorus. Abomasal contents, rumen fluid or a saline solution were given into the abomasum. Altogether forty experiments were done on four goats.The absorption of acetic acid, propionic acid, butyric acid, tritiated water (HTO) and antipyrine (AP) from the abomasum was measured. For comparison of the absorption rates, the data were given as clearance of the abomasal fluid and as water diffusion.At a mean abomasal fluid volume of 606 ± 201 ml., 513 ± 169 ml. water diffused out of the abomasum through the abomasal mucosa per hour. The antipyrine clearance was 214 ± 84 ml./hr. The volatile fatty acids (VFA) were absorbed considerably faster at acid than at neutral pH values; at pH 5·2 — 5·6 the VFA clearance was only 320 ml./hr.: at pH 3·5−4·0, however, it increased to 1130 ml./hr.The olive oil: water partition coefficients for acetic, propionic and butyric acid were measured in the pH range of 3·5 −6·2. With decreasing pH values the degree of dissociation of the acids decreases and the lipid solubility increases considerably. The permeability of the abomasal and ruminal mucosa for VFA also increases at lower pH values, but not as much as the olive oil : water partition coefficients of the acids.Absorption of VFA, HTO and AP from the abomasum is discussed in relation to the absorption of these substances from the rumen and the human stomach.