Composition of Mammary Lymph in Lactating Goats1,2

Abstract

Summary Eleven supramammary lymph ducts in eight healthy, lactating, nonpregnant goats were cannulated under anesthesia. Lymph flowed externally from freely moving, unanesthetized animals for an average period of 14 days. Jugular blood and mammary lymph from the same goat were collected simultaneously and were analyzed for protein, nonprotein nitrogen, glucose, lactose, sodium, potassium, calcium, magnesium, chloride, bicarbonate, and pH. Results showed no change in lymph composition with variations in rate of milk secretion and, except for protein concentration, no change in composition during different rates of lymph flow. Higher lymph flows were associated with decreases in lymph protein concentrations. NPN and glucose levels in lymph were not significantly different from plasma levels. Lactose was not apparent in either fluid. The electrolyte composition of lymph was similar to that of plasma when allowance was made for Donnan membrane equilibrium adjustments. Composition of mammary lymph with regard to the substances investigated appears to result from diffusion of plasma from capillaries and with no back diffusion from mammary alveoli or ducts.