Effects of dietary zinc methionine on performance and related biochemical indices in the dairy cattle

A total of twelve Chinese Holstein cows were divided into four group and the experimental design of 4×4 Latin square method: group A as the control group(basal diet),groups B,C and D as added 120,280 and 380(mg/kg) of Zn-met on the basal diet were used to investigate the effect of dietary zine methionine on performance and related biochemical indices in the dairy cattle.The results indicated that: groups B,C and D increased by 1.28(5.65%),1.59(7.02%) and 1.66(kg)(7.33%)(P0.05),and the 4% fat corrected milk(FCM) in the groups B,C and D significantly increased by 0.98(4.73%),1.22(5.89%) and 1.16(kg)(5.60%) compared with group A(P0.05);no significant differences were found among B,C and D group in milk fat percentage,lactose content,non-fat milk solids content,compared with group A(P0.05),milk protein contents of the groups B,C and D were significantly increased by 4.56,7.02 and 7.72(%)(P0.05) compared with group A;the zinc content of milk in groups B,C and D was very significantly increased(P0.01) by 1.05(36.59%),1.59(55.40%),2.08(μg/mL)(72.47%) compared with group A.The somatic cell count(SCC) of groups B,C and D were lower 1.64×104/mL(5.65%),3.23×104/mL(11.12%),3.89×104/mL(13.39%) than that in group A;DMI of groups B,C and D were increased by 0.98%,1.51%,1.66% than that in group A(P0.05);the economic analysis showed that the group C was increased 3.42 yuan RMB each cow per day than group A and was the best one.