[Distribution of enzyme concentrations in the abomasal mucosa of the preruminant calf. Age changes]

The aim of this trial was to draw an "enzyme map" of the abomasum of the preruminant calf in order to determine the secretory capacities of various areas and to study their age changes. Three pairs of calves were slaughtered at 1.5 days and at 10 and 19 weeks. The abomasum was divided into 12 parts (fig. 1). The chymosin and pepsin extracted from each part were separated and assayed. We found large individual variations in the amount and distribution of the enzymes (fig. 2, table 1) but, in all cases, more than 78 p. 100 were present in the fundus, while the antrum usually contained very little. The cardiac part contained as much as the fundic parts of similar size. The distribution of enzymes in the fundus between the parietal and visceral surfaces or between the proximal, median and distal plicae did not seem to change with age. On the contrary, that part of the enzymes provided by the ventral surface (along the greater curvature) increased with age, while the part provided by the dorsal surface (along the lesser curvature) decreased (fig. 2; table 2). However, the supply of the distal region (parts 3 + 7) of the latter surface varied within much smaller limits, and the pepsin/chymosin ratio remained close to that observed in the whole abomasum. Therefore, the distal region would be the most suitable for making an abomasal pouch which would retain the same representativeness in relation to the whole of the abomasum. It could eventually be extended on the side of the distal plica.