Selective breeding of chickens for erythrocytes with high and low leucine transport activity.

Two lines of chickens, one high and the other low uptake, have been selected for three generations for their ability to transport leucine into erythrocytes. Significant line differences were produced in one generation of selection with further separation resulting in later generations. Selection progress has been exclusively with the high-uptake line, the low line not differing significantly from the control. The maximal rate of leucine uptake, the stimulation of leucine transport by medium Na+, lysine uptake, and the Na+-K+-ATPase activity all were greater in the high line. Rates of glucose transport were not different between the lines nor were intracellular concentrations of Na+ or K+.