The changes in the flow and protein composition of thoracic duct lymph have been studied in unanæsthetized calves during the first 6 days after birth. Thoracic duct‐venous shunts were established in four calves (average body weight 35·2 kg.) within 3 hr. of birth. The calves recovered quickly from the operation and were able to suck strongly within 1–2 hr. of its completion. Lymph flow during anæsthesia varied between 90–150 ml./hr. and by 1–2 hr. after the operation, immediately before first feeding, flow had risen to values of 300–450 ml./hr. There was a marked increase in flow and globulin concentration during the 8–hr. period after the first feeding, peak values observed being 850 ml./hr. and 2·72 g. per cent, respectively. Fractionation of colostral whey and lymph on G‐200 and DEAE Sephadex columns indicated that the increase in globulin in the lymph was due to the absorption of γ1‐globulin which is present in high concentration in colostrum. Subsequently, flow and protein content decreased quite rapidly and by 24 hr. after first feeding the values were relatively constant. The results suggested that the absorption of γ‐globulin had virtually ceased by 24 hr. There was a slower decrease in lymph flow and globulin content over the subsequent 4–6 days.