The aim of this study was to investigate gamma-glutamyltransferase (GGT) activity in mammary gland during early lactation and its influence on gastrointestinal (GIT) calves proteins absorption. Twelve buffalo dams and their calves were included in the trial. Biopsies were obtained from mammary gland after delivery and GGT activity were evaluated. The highest GGT levels were found after delivery. Histochemistry confirmed these findings and revealed that GGT reactivity was distributed throughout the cytoplasm of alveolar epithelial cells. Concerning GIT studies, calves were divided in two groups according to age. The activity found in the first group (36 hours of life) in the descending and ascending duodenum and in the jejunum. Histochemistry also showed a greater enzyme activity during the first 36 hours of life. Results support the hypothesis that GGT is involved in milk production in water buffalo by supporting milk protein synthesis. Moreover, they also confirm the hypothesis that such enzyme may influence the adsorption process in the newborn calf.