The flow and lipoid composition of thoracic duct lymph in the grazing cow.

1. A technique is described for the collection of thoracic duct lymph from the grazing cow.2. The effects of continuing drainage of lymph were overcome by establishing an exteriorized lymphatico-venous shunt from which lymph and blood samples were obtained when required. The shunt functioned satisfactorily for periods of 10, 14 and 28 days in the three cows.3. The rate of lymph flow and concentration of lipids in the lymph were low during and immediately after the operation. Higher sustained levels of flow of 1.37 +/- 0.43 (S.D.), 1.88 +/- 0.40 (S.D.) and 1.90 +/- 0.45 (S.D.) 1./hr, for the dry and two lactating cows respectively, were observed during the period 3-9 days after the operation.4. More than 200% of the volume and 100% of the protein of the blood plasma compartment passed through the thoracic duct each day.5. Chlyomicron triglyceride comprised 50-70% and phospholipid 20% of the total lipid in lymph.6. The results indicated that at least 200 and 400 g of esterified fatty acid were transported daily in the lymph of the dry and lactating cows respectively.