THE ABSORPTION OF FAT IN SHEEP AND LAMBS

¹ Department of Experimental Pathology, John Curtin School of Medical Research, Australian National University, Canberra

The absorption of fat has been studied in adult sheep and in young lambs with chronic lymphatic fistulæ. When maize oil or olive oil was injected into the gut, the rate of lymph flow decreased during the next hour. The flow rate increased subsequently as fat absorption proceeded and two peaks of both flow rate and fat concentration occurred in adult sheep at 3-5 hr. and 5-8 hr. following the injection of the fat. In lambs, the lymph flow increased to a peak between 2 and 3 hr. while the peak concentration of fat in the lymph occurred between 5 and 8 hr. In adult sheep, the increase in the concentration of total esterified fatty acids was accompanied by an increase in the concentration of phospholipids in the lymph. In lambs, the concentration of total esterified fatty acids was significantly correlated with both the concentration of phospholipids and free fatty acids in the lymph during fat absorption.

When ¹⁴C tripalmitin was injected into the abomasum or duodenum of lambs, most of the absorbed radioactivity was recovered in the intestinal lymph. In adult sheep significantly less of the labelled fat which was absorbed appeared in the lymph. When the fat was given into the rumen, absorption was slow and took place over a period of several days.

More than 90 per cent of radioactivity in the lipids of the intestinal lymph was in the form of neutral glycerides. Small amounts of activity appeared in the lymph phospholipids (0-5·9 per cent) and in the lymph non-esterified fatty acids (0·6-4·5 per cent). The significance of the lymphatic system in the transport of absorbed fat in sheep is discussed.

Note:

We should like to thank Mrs. H. Kabau and Miss L. Palmer for their technical assistance.