Effects Of Zinc Methionine Supplemented On Performance And Blood Biochemical Parameters In Lactating Cows

The objections of this study to determine the effects of different levels of Zinc-Methionine(Zn-Met) supplemented on nutrient digestibility,performance,blood biochemical parameters in lactating cows,and find out the suitable dose.Eight multiparous Holstein cows in early lactation which had the adjacent milk yields,parturition date and performance,were divided into 4 groups,two cows of each group.The trial was selected in a 4×4 Latin Square design,A group was used as the control group(basic dietary) and B,C,D groups were added 100mg/kg,250mg/kg,400mg/kg Zn-Met in basic dietary(Zn34.63mg/kgDM).The results were shown as below:(l) The apparent digestibility of crude protein, ADF and NDF tended to be higher for supplemental Zn-Met groups,but no significant difference among the treatment groups (P>0.05);(2) The milk yields of the B,C,D groups were 31.48kg/d,32.23kg/d,32.03kg/d,respectively, were 5.28%(P<0.05),7.79%(P<0.01),7.12%(P<0.01) higher than A group(29.90kg/d),but no significant difference(P>0.05) among the B,C,D groups;(3) The treatment groups had no effects on milk fat, lactose and non-cream solid percentage(P>0.05).with the Zn-Met levels being enhanced, the milk protein percentage tended to be higher for the treatments groups,but no significant difference(P>0.05) among the treatment groups;(4) Zn-Met supplemented decreased the milk somatic cell counts(SCC).B,C,D groups were 10.43%,17.88%(P<0.05),19.49%(P<0.05) lower than A group;(5) The milk Zn were significantly increased (P<0.01) with the Zn-Met levels being enhanced, but the increasing extent was degressive gradually. B,C,D groups increased 66.54%,107.35%,124.63% compared with A group(P<0.01),respectively.the milk Zn of the C,D groups significantly higher than B group(P<0.01),and D group higher than C group(P<0.05);(6) The serum Zn concentrations of the B,C,D groups were 88.28%,160.00%,195.17% higher than A group(P<0.01),The serum Zn concentrations of the C,D groups significantly higher than B group(P<0.01),and D group higher than C group(P<0.05),but the increasing extent was degressive gradually;(7) B,C,D groups were significant difference(P<0.01) compared with A group in serum alkaline phosphatase(AKP) activity. The serum AKP activity of the B,C,D groups were respectively 34.53%,48.23%,45.96% higher than A group. C,D groups higher than B group(P<0.05),and D group lower than the C group, but no significantlydifference (P>0.05) between the two groups;(8) Blood urea nitrogen(BUN) of serum had tended to be lower for the treatment groups,but no significant difference(P>0.05).The economy profit of the 100mg/kg,250mg/kg,400mg/kg groups were respectively 3.69yuanRMB/head/d,4.88yuanRMB/head/d,4.32yuanRMB/head/d higher than the control group. Analysis indicated that the C(250mg/kg) group was the best during the experimention condition, and may be regard as the reference in practice.