TO research the effect of exogenous metallothionein (MT) on apoptosis rate and cell cycle of lymphocytes in peripheral blood of dairy cattle under heat stress, 20 lactating Chinese Holstein cows were selected and randomLy divided into group A, group B, group C and group D, Zn-MT in the levels of 0, 4.0, 8.0 and 12.0 mg were supplemented by intravenous injection respectively. Blood samples were collected at 1st ~,before injection) , 21st, 36th, 51st and 61st day, and the apoptosis related genes (cytc and Fast expression were determined. The ...